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1
au, jiangwu@central murdoch edu, e Jiang Wu. "Transformation of Rhizoctonia solani". Murdoch University, 2003. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20050728.141653.
Testo completoAbstract (sommario):
The aim of this study was to develop a genetic transformation system for the plant pathogenic fungus Rhizoctonia solani (teliomorph, Thanatephprus cucumeris Frank [Donk]). The availability of a transformation system would allow us to study gene exchange, epidemiology, and to use techniques such as gene disruption or gene silencing to investigate the role of fungal enzymes in pathogenesis.
The approach adopted was to use Agrobacterium tumefaciens to transform the fungus as reports in the literature suggested that this was the most efficient and easiest method to use. As a preliminary test, Fusarium oxysporum was transformed using a binary vector (pBINAN) containing a hygromycin resistance gene under control of an ascomycete promoter and terminator. Hygromycin resistant transformants were obtained after co-incubation of fungal conidia with the bacterium. The presence of the transgene was confirmed by analysis of DNA. The number of transformants depended on the genetic background of the A tumefaciens. Strains AGLO or AGRO gave higher numbers of transformants compared to LBA4404. No transformants were obtained when the hygromycin gene was under control of a basidiomycete (pBINHL1), or a plant (CaMV35S) promoter. Since the basidiomycete promoter used in pBINHL1 originates from Ustilago maydis, the vector was tested by transformation of Ustilago cynodontis. Stable transformants of U cynodontis were obtained with this vector.
A series of experiments were carried out on transformation of R. solani mycelium. Both the protoplast and the Agrobacterium transformation methods were tested. Parameters affecting protoplast production and regeneration were examined. Protoplast production varied with the age of the mycelium, with the osmotic stabilizer used, and with time of treatment with protoplasting enzymes. Regeneration of protoplasts was also affected by the osmotic stabilizer and the growth medium. Transformation of several isolates from different anastomosis groups (AG) was attempted by inducing protoplasts to take up DNA using polyethyleneglycol. Two plasmids were used; (1) pAN7-1 containing the resistance gene under control of an ascomycete promoter, and (2) pHL-1 in which the resistance gene is under control of a basidiomycete promoter. No transformants were obtained.
Attempts were then made to transform mycelium and protoplasts using A tumefaciens. The experiments used both mycelium and protoplasts as the recipient. A number of small resistant colonies were obtained using binary plasmid (pBINHL1) in which mycelium was transformed with the resistance gene was driven by the basidiomycete promoter. On transfer to fresh medium these colonies would grow to about 2cm diameter, and then stop growing. On a second transfer to fresh medium they failed to show any growth. No resistant colonies were obtained from A. tumefaciens transformation of protoplasts.
To improve transformation efficiency, a vector was constructed in which the hygromycin resistance gene was fused to an R solani laccase promoter sequence. No resistant colonies were obtained using this vector. Further experiments were carried out using a hygromycin resistance gene specially modified for expression in basidiomycetes by the insertion of artificial introns in the 5 and 3 untranslated regions, and a number of AT to CG conversions in the coding region. Most of the recipient isolates gave transformants with the unstable resistance phenotype. However, one AG 6 isolate gave transformants with a stable resistance phenotype. Of six transformants recovered from this isolate, five were shown by PCR and southern blotting to contain the transgene. In four of these transformants the resistance phenotype was stable in the absence of selection.
2
Wu, Jiang. "Transformation of Rhizoctonia solani". Thesis, Wu, Jiang (2003) Transformation of Rhizoctonia solani. PhD thesis, Murdoch University, 2003. https://researchrepository.murdoch.edu.au/id/eprint/417/.
Testo completoAbstract (sommario):
The aim of this study was to develop a genetic transformation system for the plant pathogenic fungus Rhizoctonia solani (teliomorph, Thanatephprus cucumeris Frank [Donk]). The availability of a transformation system would allow us to study gene exchange, epidemiology, and to use techniques such as gene disruption or gene silencing to investigate the role of fungal enzymes in pathogenesis.
The approach adopted was to use Agrobacterium tumefaciens to transform the fungus as reports in the literature suggested that this was the most efficient and easiest method to use. As a preliminary test, Fusarium oxysporum was transformed using a binary vector (pBINAN) containing a hygromycin resistance gene under control of an ascomycete promoter and terminator. Hygromycin resistant transformants were obtained after co-incubation of fungal conidia with the bacterium. The presence of the transgene was confirmed by analysis of DNA. The number of transformants depended on the genetic background of the A tumefaciens. Strains AGLO or AGRO gave higher numbers of transformants compared to LBA4404. No transformants were obtained when the hygromycin gene was under control of a basidiomycete (pBINHL1), or a plant (CaMV35S) promoter. Since the basidiomycete promoter used in pBINHL1 originates from Ustilago maydis, the vector was tested by transformation of Ustilago cynodontis. Stable transformants of U cynodontis were obtained with this vector.
A series of experiments were carried out on transformation of R. solani mycelium. Both the protoplast and the Agrobacterium transformation methods were tested. Parameters affecting protoplast production and regeneration were examined. Protoplast production varied with the age of the mycelium, with the osmotic stabilizer used, and with time of treatment with protoplasting enzymes. Regeneration of protoplasts was also affected by the osmotic stabilizer and the growth medium. Transformation of several isolates from different anastomosis groups (AG) was attempted by inducing protoplasts to take up DNA using polyethyleneglycol. Two plasmids were used; (1) pAN7-1 containing the resistance gene under control of an ascomycete promoter, and (2) pHL-1 in which the resistance gene is under control of a basidiomycete promoter. No transformants were obtained.
Attempts were then made to transform mycelium and protoplasts using A tumefaciens. The experiments used both mycelium and protoplasts as the recipient. A number of small resistant colonies were obtained using binary plasmid (pBINHL1) in which mycelium was transformed with the resistance gene was driven by the basidiomycete promoter. On transfer to fresh medium these colonies would grow to about 2cm diameter, and then stop growing. On a second transfer to fresh medium they failed to show any growth. No resistant colonies were obtained from A. tumefaciens transformation of protoplasts.
To improve transformation efficiency, a vector was constructed in which the hygromycin resistance gene was fused to an R solani laccase promoter sequence. No resistant colonies were obtained using this vector. Further experiments were carried out using a hygromycin resistance gene specially modified for expression in basidiomycetes by the insertion of artificial introns in the 5' and 3' untranslated regions, and a number of AT to CG conversions in the coding region. Most of the recipient isolates gave transformants with the unstable resistance phenotype. However, one AG 6 isolate gave transformants with a stable resistance phenotype. Of six transformants recovered from this isolate, five were shown by PCR and southern blotting to contain the transgene. In four of these transformants the resistance phenotype was stable in the absence of selection.
3
Wu, Jiang. "Transformation of Rhizoctonia solani". Wu, Jiang (2003) Transformation of Rhizoctonia solani. PhD thesis, Murdoch University, 2003. http://researchrepository.murdoch.edu.au/417/.
Testo completoAbstract (sommario):
The aim of this study was to develop a genetic transformation system for the plant pathogenic fungus Rhizoctonia solani (teliomorph, Thanatephprus cucumeris Frank [Donk]). The availability of a transformation system would allow us to study gene exchange, epidemiology, and to use techniques such as gene disruption or gene silencing to investigate the role of fungal enzymes in pathogenesis.
The approach adopted was to use Agrobacterium tumefaciens to transform the fungus as reports in the literature suggested that this was the most efficient and easiest method to use. As a preliminary test, Fusarium oxysporum was transformed using a binary vector (pBINAN) containing a hygromycin resistance gene under control of an ascomycete promoter and terminator. Hygromycin resistant transformants were obtained after co-incubation of fungal conidia with the bacterium. The presence of the transgene was confirmed by analysis of DNA. The number of transformants depended on the genetic background of the A tumefaciens. Strains AGLO or AGRO gave higher numbers of transformants compared to LBA4404. No transformants were obtained when the hygromycin gene was under control of a basidiomycete (pBINHL1), or a plant (CaMV35S) promoter. Since the basidiomycete promoter used in pBINHL1 originates from Ustilago maydis, the vector was tested by transformation of Ustilago cynodontis. Stable transformants of U cynodontis were obtained with this vector.
A series of experiments were carried out on transformation of R. solani mycelium. Both the protoplast and the Agrobacterium transformation methods were tested. Parameters affecting protoplast production and regeneration were examined. Protoplast production varied with the age of the mycelium, with the osmotic stabilizer used, and with time of treatment with protoplasting enzymes. Regeneration of protoplasts was also affected by the osmotic stabilizer and the growth medium. Transformation of several isolates from different anastomosis groups (AG) was attempted by inducing protoplasts to take up DNA using polyethyleneglycol. Two plasmids were used; (1) pAN7-1 containing the resistance gene under control of an ascomycete promoter, and (2) pHL-1 in which the resistance gene is under control of a basidiomycete promoter. No transformants were obtained.
Attempts were then made to transform mycelium and protoplasts using A tumefaciens. The experiments used both mycelium and protoplasts as the recipient. A number of small resistant colonies were obtained using binary plasmid (pBINHL1) in which mycelium was transformed with the resistance gene was driven by the basidiomycete promoter. On transfer to fresh medium these colonies would grow to about 2cm diameter, and then stop growing. On a second transfer to fresh medium they failed to show any growth. No resistant colonies were obtained from A. tumefaciens transformation of protoplasts.
To improve transformation efficiency, a vector was constructed in which the hygromycin resistance gene was fused to an R solani laccase promoter sequence. No resistant colonies were obtained using this vector. Further experiments were carried out using a hygromycin resistance gene specially modified for expression in basidiomycetes by the insertion of artificial introns in the 5' and 3' untranslated regions, and a number of AT to CG conversions in the coding region. Most of the recipient isolates gave transformants with the unstable resistance phenotype. However, one AG 6 isolate gave transformants with a stable resistance phenotype. Of six transformants recovered from this isolate, five were shown by PCR and southern blotting to contain the transgene. In four of these transformants the resistance phenotype was stable in the absence of selection.
4
Matthew, Jamie Scott. "Molecular diversity between anastomosis groups of Rhizoctonia solani : a thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy in the Department of Animal Sciences at the University of Adelaide". Title page, table of contents and abstract only, 1992. http://web4.library.adelaide.edu.au/theses/09PH/09phm437.pdf.
Testo completoAbstract (sommario):
Journal article co-authored by the author inserted at end (Plant pathology (1991) 40, 67-77) Includes bibliographical references (leaves 124-167) Describes the isolation of antibody and DNA probes which vary in their reaction to different anastomosis groups of Rhizoctonia solani. Evidence is presented to show that isolates from anastomosis group 8 are biochemically distinct from isolates in other anastomosis groups found in South Australia.
5
Simons, Sarah Anne. "Studies on the epidemiology of Rhizoctonia solani on Solanum tuberosum". Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333383.
Testo completo
6
Rutherford, Michael Andrew. "Biological control of Rhizoctonia solani on potatoes". Thesis, Queen's University Belfast, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336000.
Testo completo
7
McCabe, Patricia Margaret. "Characterisation of extrachromosomal elements from Rhizoctonia solani". Thesis, University of Edinburgh, 1994. http://hdl.handle.net/1842/15314.
Testo completoAbstract (sommario):
The plant pathogenic basidiomycete, Rhizoctonia solani, contains extrachromosomal double-stranded RNA and DNA elements, but the role of these elements in the biology and pathology of the fungus is uncertain. Aspects of these elements in R.solani and the role of anastomosis (hyphal fusions) in their transmission are examined here. Anastomoses between hyphae, leading to successful cell fusions and death of fused cells (vegetative incompatibility) were observed by video microscopy and by fluorescence microscopy when hyphae were loaded with fluorochromes. However, attempts to monitor organelle transfer were unsuccessful and ultra-violet irradiation of hyphae containing fluorochromes led rapidly to hyphal death. Two strains of anastomosis group (AG) 4 could readily be 'cured' of dsRNA by subculture of hyphal tips, although one strain which contained a 2.5kb DNA element could not be freed in this way, nor by ultra-violet irradiation or heating to 30°C. Several of the resulting hyphal tip subcultures showed an incompatibility reaction when paired with the respective parent strain. These parent-incompatible strains (6 from parent strain PA1 and 6 from parent strain I13) fell into 2 groups - mutually compatible within each group, but incompatible with the other group and the parent. Anastomosis during pairings of strains within any one group never led to a parent-compatible strain when subcultures were taken from the zone of hyphal fusion. There was no evidence that dsRNA influenced compatibility; instead it is suggested that hyphal tip subculturing led to segregation (or expression) of nuclear compatibility genes. Counts of nuclei in tip cells, by DAPI staining and fluorescence microscopy, showed variation in different parts of the fungal colonies, and significant tendency for some juxtaposed branch tips (arising as clusters from a single hypha) to have similar nuclear numbers to one another.
8
Noor, Afsana. "Understanding and Managing Rhizoctonia Solani in Sugarbeet". Thesis, North Dakota State University, 2013. https://hdl.handle.net/10365/26917.
Testo completoAbstract (sommario):
Rhizoctonia crown and root rot of sugarbeet (Beta vulgaris L.) caused by Rhizoctonia solani K?hn is one of the most important production problems in Minnesota and North Dakota. Greenhouse studies were conducted to determine the efficacy of azoxystrobin to control R. solani at seed, cotyledonary, 2-leaf and 4-leaf stages of sugarbeet; compatibility, safety, and efficacy of mixing azoxystrobin with starter fertilizers to control R. solani; and the effect of placement of azoxystrobin in control of R. solani. Results demonstrated that azoxystrobin provided effective control applied in-furrow or band applications before infection at all sugarbeet growth stages evaluated; mixtures of azoxystrobin and starter fertilizers were compatible, safe, and provided control of R. solani; and azoxystrobin provided effective control against R. solani when placed in contact over the sugarbeet root or into soil close to the roots.Sugarbeet Research and Education Board of Minnesota and North Dakota
9
Wiseman, Bronwyn Meg. "Characterisation of rhizoctonia barepatch decline". Title page, contents and summary only, 1996. http://web4.library.adelaide.edu.au/theses/09PH/09phw8137.pdf.
Testo completoAbstract (sommario):
Bibliography: leaves 184-209. This thesis describes the occurence of natural, biologically based suppression of Rhizoctonia barepatch in a direct drilled system at Avon, South Australia. The supressive characteristics are transferable, removed by biocidal treatments, and active against increasing doses of R. solani AG-8, Gaeumannomyces graminis var. tritici and Fusarium graminearum. Disease severity and the viable population of Rhizoctonia are reduced in suppressive soil but the causal agent is still present. The microbial populations in suppressive and non-suppressive soil appear to differ both in their functioning and composition. The control strategy is developed through manipulation of the existing soil biota with farming practices.
10
Bora, Pranjal. "Production of laccase by the phytopathogenic fungus Rhizoctonia solani". Thesis, Bora, Pranjal (2003) Production of laccase by the phytopathogenic fungus Rhizoctonia solani. PhD thesis, Murdoch University, 2003. https://researchrepository.murdoch.edu.au/id/eprint/423/.
Testo completoAbstract (sommario):
This thesis is an investigation into the production of laccases by the phytopathogenic soil fungus Rhizoctonia solani. The fungus causes maceration of plant tissue by the production of a variety of plant cell wall degrading enzymes. Whilst most attention has focused on the role of pectinases in maceration, the laccases which degrade lignin are likely to be important in this process.
The production of laccase by the AG-11 isolate VR20 in V8 medium reached a maximum after 6 days incubation. Laccase activity was unaffected by variation in temperatures over the range 4-15 degrees C, but as the temperature increased the activity increased to a maximum at 25 degrees C. This high level activity was maintained as the temperature was increased to 37 degrees C. The effects of pH on laccase activity was also determined. Activity was stable over the pH range 4.5-6. Outside this range the activity decreased significantly.
The composition of the growth medium also had a significant effect on laccase production. Similar levels of activity were observed during growth in V8, apple pectin media, or in media containing ground up lupin hypocotyls as a carbon source. However, approx 20 fold higher levels were obtained after growth in Czapek-Dox medium.
Different laccase activity band patterns were obtained by zymogram analysis of culture supernatants. The production of the other cell wall degrading enzymes pectinase,xylanase and cellulase in these media was assessed for comparison. Whilst all three were produced in V8 and apple pectin media, cellulase was not produced in lupin medium, and none of these were produced in Czapek-Dox medium.
Attempts to increase laccase production by the addition of the reported laccase inducers CuSO4.5H2O, p-anisidine, ethanol, MnSO4.7H2O, resveratrol, and tannic acid to the growth medium showed mixed results. The only case where enhancement of synthesis was observed was with the addition of MnSO4 to Czapek-Dox medium. This compound did not enhance production in the other media tested. With the exception of p-anisidine, the other inducers had minimal effect in V8, apple pectin or lupin media. Para anisidine completely inhibited production in lupin medium. With the exception of MnSO4, all inducers inhibited laccase production in Czapek-Dox medium, with p-anisidine causing complete inhibition.
The production of xylanase and cellulase was also inhibited by these inducers but in a growth medium dependent manner. Cellulase production in V8 medium was inhibited by ethanol, MnSO4, resveratrol, and tannic acid whilst only the latter two inhibited xylanase production and none of these inhibited pectinase production. In contrast, p-anisidine had a greater inhibitory effect on pectinase and xylanase production in V8 medium than on cellulase production. Para-anisidine also inhibited xylanase (and laccase) but not pectinase production in lupin medium but not in apple pectin medium. Resveratrol and tannic acid also inhibited xylanase production in lupin medium. The effects of the inhibitory compounds EDTA and SDS on laccase activity was determined. With SDS the % inhibition increased as the concentration of inhibitor decreased from 5% to 0.5%. With EDTA the opposite trend was observed. The effects of arginine on laccase activity was also tested. At concentrations of 0.5 to 5% arginine, laccase activity was completely inhibited.
Laccase activity was purified from the culture supernatant by anion exchange chromatography, and by electroelution from a native-PAGE gel. The degree of purification by each method was greater than 50 fold. Electrophoresis of the purified protein on an SDS-PAGE gel followed by staining with Coomassie blue showed two protein bands of 66 and 38 KDa. Measurement of the absorption spectrum of the purified protein showed two absorbance maxima, at 240 and 340nm.
Laccases produced by isolates from different anastomosis groups were analysed by staining gels for laccase activity. Variations in the band pattern were observed both between and within anastomosis groups. Analysis of single spore isolates from AG-8 and AG-11 showed segregation of band patterns. However the sample sizes were too small to make conclusions about the numbers of laccase enzymes produced by or the number of genes in the parent field isolates.
The role of laccases in maceration of lupin radicle tissue was investigated. Microscopic staining showed the presence of lignin in radicle tissue, and when incubated in the fungal enzymes the tissue lost integrity, characteristic symptoms of maceration. Maceration wasreadily observed as discolouring when the radicle was incubated in a solution of fungal enzyme. The degree of maceration was quantified by measuring the length of the discoloured region. Enzymes from all of the isolates tested caused maceration of lupin radicle. The degree of maceration ranged from 80-100%. No maceration was observed when agrinine was included in the reaction mixture. Arginine does not inhibit the activity of pectinases, xylanases, or cellulases. In maceration assays with potato tuber tissue which does not contain lignin, the addition of arginine to the reaction did not inhibit maceration. The results show that laccases are required for maceration of lignified tissue, but not for non-lignified tissue. Laccase gene sequences were cloned from three isolates, SCR122 (AG-6), 11034 (AG-8), and VR20 (AG-11) using degenerate primers to conserved sequences to amplify the gene sequences. The amplicons were cloned and sequenced. A BLAST search of the NCBI database with the derived amino acid sequences confirmed that the sequences were from laccase genes.
11
Bora, Pranjal. "Production of laccase by the phytopathogenic fungus Rhizoctonia solani". Murdoch University, 2003. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20040706.135422.
Testo completoAbstract (sommario):
This thesis is an investigation into the production of laccases by the phytopathogenic soil fungus Rhizoctonia solani. The fungus causes maceration of plant tissue by the production of a variety of plant cell wall degrading enzymes. Whilst most attention has focused on the role of pectinases in maceration, the laccases which degrade lignin are likely to be important in this process.
The production of laccase by the AG-11 isolate VR20 in V8 medium reached a maximum after 6 days incubation. Laccase activity was unaffected by variation in temperatures over the range 4-15°C, but as the temperature increased the activity increased to a maximum at 25°C. This high level activity was maintained as the temperature was increased to 37°C. The effects of pH on laccase activity was also determined. Activity was stable over the pH range 4.5-6. Outside this range the activity decreased significantly.
The composition of the growth medium also had a significant effect on laccase production. Similar levels of activity were observed during growth in V8, apple pectin media, or in media containing ground up lupin hypocotyls as a carbon source. However, approx 20 fold higher levels were obtained after growth in Czapek-Dox medium.
Different laccase activity band patterns were obtained by zymogram analysis of culture supernatants. The production of the other cell wall degrading enzymes pectinase,xylanase and cellulase in these media was assessed for comparison. Whilst all three were produced in V8 and apple pectin media, cellulase was not produced in lupin medium, and none of these were produced in Czapek-Dox medium.
Attempts to increase laccase production by the addition of the reported laccase inducers CuSO4.5H2O, p-anisidine, ethanol, MnSO4.7H2O, resveratrol, and tannic acid to the growth medium showed mixed results. The only case where enhancement of synthesis was observed was with the addition of MnSO4 to Czapek-Dox medium. This compound did not enhance production in the other media tested. With the exception of p-anisidine, the other inducers had minimal effect in V8, apple pectin or lupin media. Para anisidine completely inhibited production in lupin medium. With the exception of MnSO4, all inducers inhibited laccase production in Czapek-Dox medium, with p-anisidine causing complete inhibition.
The production of xylanase and cellulase was also inhibited by these inducers but in a growth medium dependent manner. Cellulase production in V8 medium was inhibited by ethanol, MnSO4, resveratrol, and tannic acid whilst only the latter two inhibited xylanase production and none of these inhibited pectinase production. In contrast, p-anisidine had a greater inhibitory effect on pectinase and xylanase production in V8 medium than on cellulase production. Para-anisidine also inhibited xylanase (and laccase ) but not pectinase production in lupin medium but not in apple pectin medium. Resveratrol and tannic acid also inhibited xylanase production in lupin medium.The effects of the inhibitory compounds EDTA and SDS on laccase activity was determined. With SDS the % inhibition increased as the concentration of inhibitor decreased from 5% to 0.5%. With EDTA the opposite trend was observed. The effects of arginine on laccase activity was also tested. At concentrations of 0.5 to 5% arginine, laccase activity was completely inhibited.
Laccase activity was purified from the culture supernatant by anion exchange chromatography, and by electroelution from a native-PAGE gel. The degree of purification by each method was greater than 50 fold. Electrophoresis of the purified protein on an SDS-PAGE gel followed by staining with Coomassie blue showed two protein bands of 66 and 38 KDa. Measurement of the absorption spectrum of the purified protein showed two absorbance maxima, at 240 and 340nm.
Laccases produced by isolates from different anastomosis groups were analysed by staining gels for laccase activity. Variations in the band pattern were observed both between and within anastomosis groups. Analysis of single spore isolates from AG-8 and AG-11 showed segregation of band patterns. However the sample sizes were too small to make conclusions about the numbers of laccase enzymes produced by or the number of genes in the parent field isolates.
The role of laccases in maceration of lupin radicle tissue was investigated. Microscopic staining showed the presence of lignin in radicle tissue, and when incubated in the fungal enzymes the tissue lost integrity, characteristic symptoms of maceration. Maceration wasreadily observed as discolouring when the radicle was incubated in a solution of fungal enzyme. The degree of maceration was quantified by measuring the length of the discoloured region. Enzymes from all of the isolates tested caused maceration of lupin radicle. The degree of maceration ranged from 80-100%. No maceration was observed when agrinine was included in the reaction mixture. Arginine does not inhibit the activity of pectinases, xylanases, or cellulases. In maceration assays with potato tuber tissue which does not contain lignin, the addition of arginine to the reaction did not inhibit maceration. The results show that laccases are required for maceration of lignified tissue,
but not for non-lignified tissue. Laccase gene sequences were cloned from three isolates, SCR122 (AG-6), 11034 (AG-8), and VR20 (AG-11) using degenerate primers to conserved sequences to amplify the gene sequences. The amplicons were cloned and sequenced. A BLAST search of the NCBI database with the derived amino acid sequences confirmed that the sequences were from laccase genes.
12
Brown, Matthew. "Elucidating crop losses and control of Rhizoctonia solani and Rhizoctonia cerealis in winter wheat". Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33622/.
Testo completoAbstract (sommario):
Rhizoctonia solani is a species complex comprising 13 anastomosis groups (AG) that cause disease in a broad range of crops. Various AGs of R. solani are pathogenic to winter wheat causing damping-off and root rots. Rhizoctonia cerealis, the fungal agent of sharp eyespot, is known to commonly occur on the stems of wheat as part of stem base disease complex (SBD) consisting also of eyespot and brown foot rot (BFR). Eyespot is caused by Oculimacula acuformis or O. yallundae and BFR is principally caused by Microdochium nivale or M. majus. The population dynamics of SBD pathogens are continually changing due to environmental and agronomic pressures. Therefore, information on the current population dynamics and factors that influence population changes can guide the implementation of effective control measures. Furthermore the presence and dynamics of Rhizoctonia spp. in English wheat crops has not been previously investigated and there is also limited knowledge on the yield losses associated with root and stem base rhizoctonia diseases in wheat. This work aimed to elucidate crop losses and control of R. solani and R. cerealis in English wheat crops. An investigation was conducted into the incidence and severity of root and stem base diseases and population dynamics of their associated pathogens in 102 English winter wheat crops. Crop losses and control of the main Rhizoctonia spp. identified in English wheat crops were further investigated in artificially inoculated field experiments. Additional characterisation of Rhizoctonia spp. was investigated using ITS sequencing, isolate pathogenicity and in vitro fungicide sensitivity experiments. The predominant AG of R. solani in English winter wheat crops identified in 63% of soil samples was AG 2-1 with the highest DNA concentrations found in soil where the previous crop was oilseed rape. This suggests that OSR in the rotation is selecting for AG 2-1. Field experiments showed that wheat was not a major host of AG 2-1 since the pathogen failed to cause significant effects on wheat growth and yield. Sharp eyespot co-occurred with eyespot and BFR in English wheat crops. In 2011/12 at GS 65-75 sharp eyespot symptoms and R. cerealis DNA were detected in 90 and 94% of crops, respectively. The population structure of R. cerealis in English wheat crops revealed all isolates belonged to the subgroup AG D-I. Sharp eyespot incidence and severity showed considerable season to season variation primarily due to environmental conditions with cool, wet and humid summer conditions favouring the disease. However, agronomy practices did not have a major influence on sharp eyespot and R. cerealis DNA in soil or in planta. In field experiments R. cerealis caused significant plant establishment losses, stem browning and reduction in grain yield of 8.5% in winter wheat. The pathogenicity of R. cerealis isolates to wheat was confirmed in controlled environment experiments where significant damping-off and stem browning on 10 day old wheat seedlings occurred. In this study root rot was not correlated with any pathogen and was likely caused by a complex of species. Root rot incidence and severity in English wheat fields and in field experiments showed a decreasing trend in both seasons. BFR was the predominant SBD in English wheat crops occurring in 100% of crops by GS 37 in both seasons. Eyespot showed season to season variation and was favoured by warm, wet and humid conditions in the spring. The causal agents of eyespot the Oculimacula spp. were the most common occurring species in the soil and in planta of English wheat crops. DNA of Oculimacula spp. and Microdochium spp. was detected in ≥90% of stem bases in both seasons, showing these species are ubiquitous in English wheat crops. Results indicated a shift in the Oculimacula spp. population in English wheat crops with both species occurring together although O. yallundae was clearly the predominant species in terms of biomass. Protecting plants in the establishment phase of development from Rhizoctonia spp. is critical as early infections can lead to seedling death. Seed treatments are considered the most effective way to target and deliver fungicides to control infections by Rhizoctonia spp. In field experiments sedaxane + fludioxonil provided more consistent control of damping-off and stem browning than fludioxonil alone. In addition, fungicide EC50 values to inhibit mycelial growth of R. solani and R. cerealis isolates were lower for sedaxane than fludioxonil or prothioconazole. Sedaxane + fludioxonil also significantly reduced BFR up to GS 39, but showed inconsistent control of sharp eyespot beyond GS 13. To conclude, this study has found that AG 2-1 is widespread in English wheats crops and this may have implications for the growth and development of OSR. Rhizoctonia cerealis was shown to significantly reduced emergence and grain yield of winter wheat. This suggests control of this pathogen should receive greater attention especially at the establishment phase of development and that seed treatments (i.e. sedaxane) are the most effective control option to protect seedlings.
13
Balali-Dehkordi, Gholam Reza. "Genetic variation of Rhizoctonia solani AG-3 in South Australia". Title page, contents and abstract only, 1996. http://web4.library.adelaide.edu.au/theses/09PH/09phb171.pdf.
Testo completoAbstract (sommario):
Three pages of addenda pasted inside back cover. Bibliography: leaves 166-189. Rhizoctonia solani is a complex species comprising morphologically basidiomycetous imperfect fungi. This study aimed to determine genetic diversity within R. solani AG-3 causing rhizoctonia disease of potato in South Australia. For this purpose, pectic zymogram, PCR, DNA fingerprinting and RFLP techniques were used in conjunction with traditional plant pathology procedures.
14
Bueno, César Júnior [UNESP]. "Efeito da solarização do solo sobre a população de Pseudomonas spp. fluorescente antagonista a Rhizoctonia solani Kuhn GA 4 HGI". Universidade Estadual Paulista (UNESP), 2001. http://hdl.handle.net/11449/97214.
Testo completoAbstract (sommario):
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O trabalho foi realizado nas instalações do Departamento de Produção Vegetal/Defesa Fitossanitária da Faculdade de Ciências Agronômicas-UNESP (22º51’S e 48º26’W)- Botucatu/SP e consistiu da instalação de dois experimentos idênticos em épocas distintas com duas etapas cada. A primeira destas objetivou verificar o efeito da solarização sobre a comunidade nativa de Pseudomonas spp. fluorescentes no campo e em túnel plástico. Nesta fase, monitorou-se a população das bactérias aos 0, 7, 14, 21, 28 e 35 dias durante a solarização. Na segunda etapa, verificou-se a indução de supressividade do solo, no controle da doença, em feijoeiro na cultivar ‘IAC Carioca’, causada por Rhizoctonia solani GA 4 HGI, agente causal do ‘damping-off’ do feijoeiro, através do emprego do solo previamente solarizado ou não, transportado para vasos, sob condições de casa-de-vegetação. Monitorou-se a população das bactérias em meio B de King e o índice de severidade de R. solani aos 7, 14 e 21 dias após a semeadura através de escala de notas. Para a inoculação o fungo foi cultivado em substrato areno-orgânico e incorporado ao solo na proporção de 0,5% p/v. A detecção endofítica ou epífita de Pseudomonas spp. fluorescentes em sementes de feijão, o teste de antagonismo a Rhizoctonia solani e a caracterização genérica através de testes morfológicos e bioquímicos, foram feitos em condições de laboratório. O tempo de solarização foi de 35 dias nos períodos de 19/11/99 a 24/12/99 e de 17/02/00 a 23/03/00. Observou-se maiores temperaturas em túnel plástico nos dois períodos. As maiores médias máximas no campo e túnel plástico foram maiores no primeiro período do que no segundo. A solarização e ausência de cobertura vegetal diminuíram a população das bactérias a níveis indetectáveis no campo e túnel... .
The study was carried out at the Departament of Plant Production - UNESP– Botucatu/SP, Brazil (22º51’S and 48º26’W). The study consisted of two identical experiments installed in different periods with two stages each. The objective of the first experiment was to verify the effect of solarization on the native community of fluorescent Pseudomonas spp. under field and plastic tunnel conditions. The bacterium population was monitored at 0, 7, 14, 21, 28 and 35 days of solarization. In the second experiment, it was verified a possible induction of soil suppressiveness to control disease, caused by Rhyzoctonia solani GA 4 HGI on bean ‘IAC Carioca’, through solarized or not solarized soil transferred to vases, under greenhouse conditions. The bacterium population was monitored in King’s B medium and the severity rate of R. solani was determined at the 7, 14 and 21 days after sowing using a scale of notes. R. solani was cultivated for inoculation in sand-organic substratum and incorporated at the soil in the 0.5 w/v proportion. The detection of the endophytic or epiphytic forms of the fluorescent Pseudomonas spp. in bean seeds, the antagonism test against Rhizoctonia solani and the generic characterization by the morphological and biochemistry tests were made under laboratory conditions. The extension of the solarization was 35 days, from 11/19/00 to 12/24/00 and from 02/17/00 to 03/23/00. The greatest temperatures were observed in plastic tunnel in both periods. The greatest maximum media temperatures were bigger in the first period than in the second one. The soil solarization and the absence of vegetable mulching decreased the bacteria population at undetected levels in the field and tunnel. The soil solarization in the field and tunnel did not induce soil suppressiveness to R. solani. It was not observed endophytic and epiphytic forms of... (Complete abstract, click electronic address below).
15
Bueno, César Júnior. "Efeito da solarização do solo sobre a população de Pseudomonas spp. fluorescente antagonista a Rhizoctonia solani Kuhn GA 4 HGI /". Botucatu : [s.n.], 2001. http://hdl.handle.net/11449/97214.
Testo completoAbstract (sommario):
Orientador: Nilton Luiz de SouzaResumo: O trabalho foi realizado nas instalações do Departamento de Produção Vegetal/Defesa Fitossanitária da Faculdade de Ciências Agronômicas-UNESP (22º51'S e 48º26'W)- Botucatu/SP e consistiu da instalação de dois experimentos idênticos em épocas distintas com duas etapas cada. A primeira destas objetivou verificar o efeito da solarização sobre a comunidade nativa de Pseudomonas spp. fluorescentes no campo e em túnel plástico. Nesta fase, monitorou-se a população das bactérias aos 0, 7, 14, 21, 28 e 35 dias durante a solarização. Na segunda etapa, verificou-se a indução de supressividade do solo, no controle da doença, em feijoeiro na cultivar 'IAC Carioca', causada por Rhizoctonia solani GA 4 HGI, agente causal do 'damping-off' do feijoeiro, através do emprego do solo previamente solarizado ou não, transportado para vasos, sob condições de casa-de-vegetação. Monitorou-se a população das bactérias em meio B de King e o índice de severidade de R. solani aos 7, 14 e 21 dias após a semeadura através de escala de notas. Para a inoculação o fungo foi cultivado em substrato areno-orgânico e incorporado ao solo na proporção de 0,5% p/v. A detecção endofítica ou epífita de Pseudomonas spp. fluorescentes em sementes de feijão, o teste de antagonismo a Rhizoctonia solani e a caracterização genérica através de testes morfológicos e bioquímicos, foram feitos em condições de laboratório. O tempo de solarização foi de 35 dias nos períodos de 19/11/99 a 24/12/99 e de 17/02/00 a 23/03/00. Observou-se maiores temperaturas em túnel plástico nos dois períodos. As maiores médias máximas no campo e túnel plástico foram maiores no primeiro período do que no segundo. A solarização e ausência de cobertura vegetal diminuíram a população das bactérias a níveis indetectáveis no campo e túnel... (Resumo completo, clicar acesso eletrônico abaixo).
Abstract: The study was carried out at the Departament of Plant Production - UNESP- Botucatu/SP, Brazil (22º51'S and 48º26'W). The study consisted of two identical experiments installed in different periods with two stages each. The objective of the first experiment was to verify the effect of solarization on the native community of fluorescent Pseudomonas spp. under field and plastic tunnel conditions. The bacterium population was monitored at 0, 7, 14, 21, 28 and 35 days of solarization. In the second experiment, it was verified a possible induction of soil suppressiveness to control disease, caused by Rhyzoctonia solani GA 4 HGI on bean 'IAC Carioca', through solarized or not solarized soil transferred to vases, under greenhouse conditions. The bacterium population was monitored in King's B medium and the severity rate of R. solani was determined at the 7, 14 and 21 days after sowing using a scale of notes. R. solani was cultivated for inoculation in sand-organic substratum and incorporated at the soil in the 0.5 w/v proportion. The detection of the endophytic or epiphytic forms of the fluorescent Pseudomonas spp. in bean seeds, the antagonism test against Rhizoctonia solani and the generic characterization by the morphological and biochemistry tests were made under laboratory conditions. The extension of the solarization was 35 days, from 11/19/00 to 12/24/00 and from 02/17/00 to 03/23/00. The greatest temperatures were observed in plastic tunnel in both periods. The greatest maximum media temperatures were bigger in the first period than in the second one. The soil solarization and the absence of vegetable mulching decreased the bacteria population at undetected levels in the field and tunnel. The soil solarization in the field and tunnel did not induce soil suppressiveness to R. solani. It was not observed endophytic and epiphytic forms of... (Complete abstract, click electronic address below).
Mestre
16
Mayer, Silvia. "Untersuchungen zu Rhizoctonia solani - dem Erreger der dry-core-Krankheit der Kartoffel". [S.l. : s.n.], 2004. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB11195184.
Testo completo
17
Wareing, Peter William. "Studies on Rhizoctonia solani causing bottom rot of lettuce". Thesis, University of Hull, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327855.
Testo completo
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Robinson, Helen Lynne. "Characterization of double-stranded RNA (dsRNA) from Rhizoctonia solani". Thesis, University of Edinburgh, 1999. http://webex.lib.ed.ac.uk/abstracts/robins01.pdf.
Testo completo
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Zamani, Mohammad Reza. "The pectic enzymes of Rhizoctonia solani AG-8 strains". Thesis, Zamani, Mohammad Reza (1995) The pectic enzymes of Rhizoctonia solani AG-8 strains. PhD thesis, Murdoch University, 1995. https://researchrepository.murdoch.edu.au/id/eprint/51917/.
Testo completoAbstract (sommario):
Isolates of Rhizoctonia solcmi anastomosis group 8 (AG-8) cause bare patch disease in cereal and legume crops. Infection of root tissue by the fungus leads to maceration of the roots and inhibits development of the aerial parts of the plant. There is evidence to suggest that pectic enzymes may be an important factor in the pathogenicity of R. solani. The aim of this study is to investigate the role of pectolytic enzymes produced by R. solani (AG-8) isolates in pathogenicity.
Pectic enzyme production by highly virulent (HV) and weakly virulent (WV) isolates from wheat bare patches was analyzed. The predominant type of pectolytic activity produced by both types of strains was polygalacturonase (PG). Staining of isoelectric focusing gels for PG activity revealed differences in the PG isoenzymes produced by HV and WV strains. The differences were more clearly observed in single spore progeny derived from one of the HV strains. Analysis of enzymatic breakdown products of HV and WV enzymes with polygalacturonic acid suggested that the enzymes are endopectinases. Four isoenzyme forms of PCs, from both HV and WV strains, were separated and purified by ion exchange chromatography. Their characteristics; including isoelectric point, molecular masses, and pH optimum; were determined. All, except one isozyme from HV strain degrade polygalacturonic acid by producing oligosaccharide intermediates. One of the isozymes from HV strain does not produce these intermediates. Bioassay of the degradation products showed that these oligosaccharide products induced synthesis of Phenylalanine Ammonia Lyase (PAL), a key enzyme in the defence of the plant.
Genomic DNA of R. solani and Aspergillus niger was amplified by PCR using two degenerate primers designed from conserved regions in the amino acid sequences of Aspergillus tiiger PG genes. A single product was obtained from A. niger, whilst multiple products were obtained from R. solani. A southern blot of the amplified products was probed with the product from A. niger. The probe hybridized to single band of the same size as the A niger product. The sequence of this Rhizoclonia band showed that it is a pectinestrase gene. A number of positive plaques were detected when the genomic library (RMZ1) was screened with this gene.
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Budge, Giles Elliott. "Detection and characterisation of Rhizoctonia solani affecting UK Brassica crops". Thesis, University of Reading, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486318.
Testo completoAbstract (sommario):
Rhizoctonia so/ani is the causative agent of wirestem on Brassica crops. R. so/ani is a species complex comprising genetically. distinct groups known as anastomosis groups (AGs). Knowledge of which AGs are responsible for disease is necessary to formulate appropriate management strategies. Important knowledge about the specific AGs responsible for disease in UK Brassica crops and where in the production chain the fungus became associated with plants was lacking. A survey of UK .f3rassica o/eracea crops was completed to. establish which anastomosis groups of Rhizoctonia so/ani were associated with module raised plants. No R. so/ani was recovered from plants collected directly from UK propagators. R. so/ani was identified from asymptomatic stem bases collected from field crops using classical mycology, suggesting field inoculum is important. Such data suggests UK propagation houses have high standards of hygiene and future research should concentrate on elucidating the field biology of R. so/ani. The pathogenicity of the recoveredi.isolates was demonstrated across a range of crops, including B. o/eracea. However, the isolates were not pathogenic to monocotyledonous species suggesting these may act as effective break crops. Sequence data were generated from ribosomal and ~-tubulin regions and the anastomosis groups of the R. so/ani isolates identified using parsimony and Bayesian based phylogenetic methods. Both methods suggested the majority of isolates recovered from the stem bases of UK B. o/eracea plants belonged to AG2-1 and all but one of the remaining isolates belonged to AG4 HGii. These data are consistent with research from the USA, however this is the first report for UK crops. AG determination using nucleotide sequence information proved more successful and less time consuming than classical mycological approaches. AG2-1 formed three distinct clusters in all analyses suggesting this' subgroup is genetically diverse, a conclusion supported by the problems encountered when investigating AGs using classical mycology. The monophyly of genera Ceratobasidium and Thanatephorus were investigated using constrained analyses, however no firm conclusions could be drawn to accept or reject this hypothesis. Protocols were devel~edto' deteet AG 'and ·spedfic sub~groups in plant and ·soil samples using real-time peR. Soil testing suggested AG2-1 was more frequently detected in samples collected from the upper 10 cm of fields used for B. oleracea production. Such information is consistent with other research and suggests the growth of R. solani may be limited by lack of air filled pores within soil matrixes. The molecular methods were used to investigate the spatial and temporal association of R. solani with field grown B. oleracea plants. The molecular protocols confirmed that R. solani AG2-1 became rapidly associated with a large number of B. oleracea plants. The principle arguments for such an association hinged on identifying the dominant behaviour expressed by the fungus. Rapid colonisation of the root system and stem base would benefit saprophytic behaviour of R. solani as the fu.ngus could capitalise when the crop lifecycle was complete. As a pathogen the benefits of early colonisation are clear and perhaps the reason for low disease levels can be explained by the absence of suitable environmental conditions for disease to progress. A third hypothesis could be that R. solani may form mycorrhizal associations with B. oleracea crops.
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Creaser, M. L. "Spatio-temporal dynamics of saprophytic populations of Rhizoctonia solani Kühn". Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598143.
Testo completoAbstract (sommario):
Rhizoctonia solani is a vigorous soilborne, fungal plant pathogen that is responsible for substantial losses to many agriculturally important crops. The pathogen's destructive nature and wide host range has promoted considerable research into its taxonomy, pathology, and ecology, in an effort to develop effective methods of disease control. The population dynamics of R. solani have received considerable attention in regard to plant infection and disease development. However, few studies have focused on the saprophytic population dynamics of this organism that has been described as a saprophyte in which parasitism is largely incidental to saprophytism. The objectives of the present study were to investigate the effects of abiotic and biotic factors, principally incubation temperature and the presence of the fungal antagonist Trichoderma viride, on the temporal and spatio-temporal dynamics of saprophytic populations of two isolates of R. solani under controlled environment conditions. The saprophytic population dynamics of R. solani were investigated using a combination of fungal quantification techniques and inoculum placement studies. After investigation of the Enzyme Linked Immunosorbent Assay, ELISA, as a tool for quantification of R. solani, in comparison with ATP and chitin assays, ELISA was selected as the most appropriate assay for an investigation of population dynamics. Inoculum placement studies were used to evaluate the effects of T. viride on the growth and ability of R. solani to colonise a substrate from varying distances. The progress of the parasitic phase of R. solani is determined by, among other factors, initial inoculum density, propagule size and isolate. This study has shown that saprophytic populations of R. solani exhibit cycles of fungal activity that are affected by interactions between temperature with initial inoculum components and isolate. These factors determine the magnitude, duration and timing of cycles of saprophytic activity, as measured by ELISA. In no instance was the antagonist, T. viride, able to eliminate R. solani within a microcosm. Placement studies, in which propagules of T. viride were placed at varying distances from propagules of R. solani, concluded that the controlling effects of T. viride were localised and limited due to the slow growth of the fungus from its initial substrate in comparison with the growth of R. solani.
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Robertson, Shelly Ray. "ULTRASTRUCTURE OF ANASTOMOSIS IN RHIZOCTONIA SOLANI (AUTORADIOGRAPHY, TRANSLOCATION, HYPHAL-FUSION)". Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/291254.
Testo completo
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Kabir, Nasreen Zahan. "Selection of effective antagonists against Rhizoctonia solani (AG-3), the causal agent of Rhizoctonia disease of potato". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq29726.pdf.
Testo completo
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Kabir, Nasreen Zahan. "Selection of effective antagonists against Rhizoctonia solani (AG-3), the causal agent of Rhizoctonia disease of potato". Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27351.
Testo completoAbstract (sommario):
Rhizoctonia solani (AG-3), the causal agent of Rhizoctonia disease of potato, overwinters as sclerotia on potato tubers. To develop a biocontrol strategy based on the prevention of the sclerotial germination, an isolation of microorganisms colonizing sclerotia of infected potato tubers (cultivars Norland, Atlantic and Souris), was conducted. In vitro screening was used to select effective antagonistic fungi against Rhizoctonia solani. Fifty fungal isolates were selected in order to cover all identified genera and potato variety and examined for their ability to inhibit germination of sclerotia which were incubated with the test fungus for 14 days. Twenty-four (24) fungal isolates were retained based on their ability to reduce sclerotial viability by more than 50% as compared with 100% viability of untreated sclerotia. These 24 isolates were further examined for their ability to protect Table beet seedlings against the pathogen in greenhouse soils. Based on their ability to protect Table beet seedlings from Rhizoctonia infections and to increase the number of secondary roots and root length isolates, F2, F11, F132, F158, and F258 were screened and test their efficacy to increase beet seed germination in field soils. (Abstract shortened by UMI.)
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Kyritsis, Polyvios. "Epidemiology and pathogenesis of mycelial soil borne Rhizoctonia solani AG 3 on potatoes (Solanum tuberosum)". Thesis, University of Aberdeen, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288350.
Testo completoAbstract (sommario):
This thesis describes aspect of the epidemiology and pathogenicity of the soil-borne phase of Rhizoctonia solani AG-3 (Kuhn) fungus on potatoes and its competitive saprophytic colonisation ability in the soil. Under controlled environmental conditions, stem canker incidence and severity increased with increasing levels of soil-borne inoculum but plateaued after ¼ inoculum level (i.e 1 Petri dish of R. solani AG-3 per kg soil). Up to the 1/20 inoculum stem canker occurred at a low level. A significant increase occurred at 1/10 and 1/8 inoculum levels. A similar pattern was observed for the competitive saprophytic colonisation ability of the fungus. The fungus was attracted more by seed tubers than by stems and the incidence of black scurf was higher than stem canker at all inoculum levels tested. Sclerotia developed on seed tubers even at low inoculum levels. Favourable soil conditions for infection on stems and seed tubers were 10oC and soil moisture content of 40% water holding capacity. Optimum moisture content for saprophytism was between 20-50% water holding capacity, although optimum levels of the individual soils tested varied. Pot and laboratory experiments indicated that conditions for development of R. solani were more conducive in heavy than in light textured soils. When fine sand was added in increasing quantities to a sandy clay loam soil, the disease initiated by the fungus was steadily reduced with an increase in sand content. Potato cultivars differed in their susceptibility to R. solani at early stages of growth but none of the cultivars tested showed complete resistance to the disease. Depth of planting had no significant effect of Rhizoctonia stem and seed tuber infection.
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Ridout, C. J. "Biological control of Rhizoctonia solani on lettuce with species of Trichoderma". Thesis, University of Hull, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376233.
Testo completo
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Woodhall, James Warwick. "Characterisation of Rhizoctonia solani anastomosis groups and their pathogenicity to potato". Thesis, Open University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417459.
Testo completo
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Fenille, Roseli Chela [UNESP]. "Caracterização citomorfológica, cultural, molecular e patogênica de Rhizoctonia solani Kühn associado a soja no Brasil". Universidade Estadual Paulista (UNESP), 2001. http://hdl.handle.net/11449/105440.
Testo completoAbstract (sommario):
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fenille_rc_dr_botfca.pdf: 795582 bytes, checksum: 759ea8f4173e60afb2c35123120e9e29 (MD5)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Rhizoctonia solani representa um patógeno de importância econômica mundial nas áreas de cultivo da soja. Pode estar associado a vários sintomas como tombamento, podridão de raízes e hipocótilos e mela ou requeima da soja. No Brasil, os níveis de danos pela mela em soja variam de 31 a 60%, em lavouras dos Estados do Norte e Nordeste. R. solani está dividido em 14 grupos de anastomose (AG), que diferem quanto aos aspectos culturais, virulência e fisiologia. Desta forma, objetivou-se caracterizar AG de R. solani associados à soja no Brasil. Dentre 73 isolados analisados quanto a condição nuclear, 6 foram binucleados e 67 multinucleados. Os isolados multinucleados (R. solani) foram caracterizados através de anastomose de hifas, temperaturas limites para crescimento micelial, requerimento de tiamina, temperatura letal, produção de escleródios e comparações por RAPD. Através de anastomose de hifas, 4 isolados causadores de tombamento e podridão de hipocótilos foram caracterizados como AG-4. Análises de RAPD permitiram verificar que três, desses quatro isolados, pertenciam ao AG-4 HGII, e o outro ao AG-4 HGI. Através da fusão de hifas com AG-2-2 IIIB, crescimento a 35oC e auxotrofismo para tiamina, foi caracterizado um isolado, causador de tombamento e podridão de raízes e hipocótilos. Sessenta e dois isolados, causadores de mela, realizaram anastomose de hifas com o AG-1 IA apresentando em média 19,3 mm/dia de crescimento radial , formando escleródios tipo ‘sasakii’, característicos desse subgrupo. O enquadramento desses isolados no subgrupo IA foi confirmado pela análise de RAPD entre os isolados de R. solani de soja e padrões dos subgrupos do AG-1. Estruturas sexuais de Thanatephorus cucumeris (anamorfo R. solani) foram produzidas por um isolado do AG-1 IA, em condições de estufa biológica à temperatura de 28±1oC... .
Rhizoctonia solani represents a pathogen economically important in all soybean-growing areas in the world. It causes pre- and post-emergence damping-off, root and hypocotyl rot and foliar blight of soybean. Foliar blight has resulted in yield losses of 31-60% in North and Northeast of Brazil. R. solani is divided into 14 anastomosis groups (AG), that differ in cultural appearance, virulence, physiology and genetic. The aim of this study was to characterize R. solani isolates associated with soybean in Brazil. Among seventy-three Rhizoctonia isolates examined according to nuclear condition, six were binucleate and sixtyseven were multinucleate. The multinucleate isolates (R. solani) were characterized according to anastomosis group, limit temperature to radial growth, thiamine requirement, lethal temperature, sclerotia production and molecular marker RAPD. Four isolates, cause of damping-off and hypocotyl rot, belonged to AG-4. RAPD analysis showed that among four isolates of AG-4, three grouped with HGII and one belonged to HGI subgroup. Other isolate, cause of damping-off and root and hypocotyl rot, growth at 35oC in the dark and thiamine auxotrophic, belonged to AG-2-2 IIIB. Sixty-two isolates, cause of foliar blight, belonged to AG-1 IA. The mean radial growth rate was 19,3 mm/day and producing sasakii-type sclerotia, characteristic to the IA subgroup. RAPD analysis among R. solani AG-1 IA isolates of the soybean and anastomosis group testers, corroborate the characterization in IA subgroup. Perfect-stage Thanatephorus cucumeris (anamorph Rhizoctonia solani) was produced by one AG-1 IA isolate, in incubator at 28±1oC. The AG-4 and AG-2-2 IIIB isolates were pathogenic in soybean seedlings cv. ‘FT-Cristalina’, under greenhouse condition, causing damping-off and root and hypocotyl rot. The AG-2-2 IIIB isolate caused large lesions and cortex... (Complete abstract, click electronic address below).
29
Fenille, Roseli Chela. "Caracterização citomorfológica, cultural, molecular e patogênica de Rhizoctonia solani Kühn associado a soja no Brasil /". Botucatu : [s.n.], 2001. http://hdl.handle.net/11449/105440.
Testo completoAbstract (sommario):
Orientador: Nilton Luiz de SouzaResumo: Rhizoctonia solani representa um patógeno de importância econômica mundial nas áreas de cultivo da soja. Pode estar associado a vários sintomas como tombamento, podridão de raízes e hipocótilos e mela ou requeima da soja. No Brasil, os níveis de danos pela mela em soja variam de 31 a 60%, em lavouras dos Estados do Norte e Nordeste. R. solani está dividido em 14 grupos de anastomose (AG), que diferem quanto aos aspectos culturais, virulência e fisiologia. Desta forma, objetivou-se caracterizar AG de R. solani associados à soja no Brasil. Dentre 73 isolados analisados quanto a condição nuclear, 6 foram binucleados e 67 multinucleados. Os isolados multinucleados (R. solani) foram caracterizados através de anastomose de hifas, temperaturas limites para crescimento micelial, requerimento de tiamina, temperatura letal, produção de escleródios e comparações por RAPD. Através de anastomose de hifas, 4 isolados causadores de tombamento e podridão de hipocótilos foram caracterizados como AG-4. Análises de RAPD permitiram verificar que três, desses quatro isolados, pertenciam ao AG-4 HGII, e o outro ao AG-4 HGI. Através da fusão de hifas com AG-2-2 IIIB, crescimento a 35oC e auxotrofismo para tiamina, foi caracterizado um isolado, causador de tombamento e podridão de raízes e hipocótilos. Sessenta e dois isolados, causadores de mela, realizaram anastomose de hifas com o AG-1 IA apresentando em média 19,3 mm/dia de crescimento radial , formando escleródios tipo 'sasakii', característicos desse subgrupo. O enquadramento desses isolados no subgrupo IA foi confirmado pela análise de RAPD entre os isolados de R. solani de soja e padrões dos subgrupos do AG-1. Estruturas sexuais de Thanatephorus cucumeris (anamorfo R. solani) foram produzidas por um isolado do AG-1 IA, em condições de estufa biológica à temperatura de 28±1oC... (Resumo completo, clicar acesso eletrônico abaixo).
Abstract: Rhizoctonia solani represents a pathogen economically important in all soybean-growing areas in the world. It causes pre- and post-emergence damping-off, root and hypocotyl rot and foliar blight of soybean. Foliar blight has resulted in yield losses of 31-60% in North and Northeast of Brazil. R. solani is divided into 14 anastomosis groups (AG), that differ in cultural appearance, virulence, physiology and genetic. The aim of this study was to characterize R. solani isolates associated with soybean in Brazil. Among seventy-three Rhizoctonia isolates examined according to nuclear condition, six were binucleate and sixtyseven were multinucleate. The multinucleate isolates (R. solani) were characterized according to anastomosis group, limit temperature to radial growth, thiamine requirement, lethal temperature, sclerotia production and molecular marker RAPD. Four isolates, cause of damping-off and hypocotyl rot, belonged to AG-4. RAPD analysis showed that among four isolates of AG-4, three grouped with HGII and one belonged to HGI subgroup. Other isolate, cause of damping-off and root and hypocotyl rot, growth at 35oC in the dark and thiamine auxotrophic, belonged to AG-2-2 IIIB. Sixty-two isolates, cause of foliar blight, belonged to AG-1 IA. The mean radial growth rate was 19,3 mm/day and producing sasakii-type sclerotia, characteristic to the IA subgroup. RAPD analysis among R. solani AG-1 IA isolates of the soybean and anastomosis group testers, corroborate the characterization in IA subgroup. Perfect-stage Thanatephorus cucumeris (anamorph Rhizoctonia solani) was produced by one AG-1 IA isolate, in incubator at 28±1oC. The AG-4 and AG-2-2 IIIB isolates were pathogenic in soybean seedlings cv. 'FT-Cristalina', under greenhouse condition, causing damping-off and root and hypocotyl rot. The AG-2-2 IIIB isolate caused large lesions and cortex... (Complete abstract, click electronic address below).
Doutor
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Tullio, Hamilton Edemundo. "POTENCIAL DE BACTÉRIAS ENDOFÍTICAS DO CACAU PARA O CONTROLE DE FUNGOS DE SOLO E PROMOÇÃO DE CRESCIMENTO RADICULAR NA CULTURA DA SOJA". Universidade Estadual de Ponta Grossa, 2017. http://tede2.uepg.br/jspui/handle/prefix/2398.
Testo completoAbstract (sommario):
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
A preocupação da sociedade com o excessivo uso de agrotóxicos utilizados na agricultura, para o controle de doenças, gera uma grande demanda de pesquisas com métodos de controle ambientalmente menos agressivos. Dentre eles, destaca-se o controle biológico. O uso de relações antagônicas, exercidas por microrganismos, tais como: antibiose, competição, parasitismo, predação e a indução de resistência em plantas, oferece uma vasta gama de oportunidades para a utilização de microrganismos que, ainda, são pouco conhecidos como os microrganismos endofíticos. O objetivo do trabalho foi realizar um levantamento do potencial de controle biológico de bactérias endofitícas isoladas do cacau, para os patógenos de solo Fusarium solani, Rhizoctonia solani e Sclerotinia sclerotiorum e sua ação na promoção do crescimento radicular de plantas de soja. Foram avaliadas 22 bactérias endofíticas em relação a seu potencial antagônico in vitro, pelo método de cultivo pareado com os fitopatógenos, utilizando como parâmetros: a formação de halo de inibição exercido pelas bactérias, o tamanho da colônia do patógeno e a porcentagem de inibição do crescimento micelial do patógeno. Os parâmetros utilizados para avaliar o potencial de controle das bactérias endofíticas sobre fungos de solo e a promoção do crescimento radicular in vivo foram: a porcentagem de emêrgencia de plantas, a altura de plantas, a porcentagem de plantas anormais, a severidade de doença, o volume de raízes, as massas fresca e seca de raízes e das partes áerea e total das plantas. Foram encontrados 9 isolados (TCB 02, TCB 7, TCB 08, TCB 10, TCB 11, TCB 17, TCB 18, TCB 19 e TBC 20), que apresentaram mais de 75% de inibição para pelo menos um dos patógenos testados nos experimentos in vitro, demonstrando alto potencial antagônico. O isolado bacteriano TCB 10, identificado como Paenibacillus e o isolado bacteriano TCB 08, identificado como Staphylococcus apresentaram potencial antagônico para os três fitopatógenos. Os isolados TCB 17, TCB 18 e TCB 19 apresentaram potencial antagônico para S. sclerotiorum. Para os testes com o tratamento de sementes o isolado bacteriano TCB 10 apresentou redução da severidade de R. solani. Não se pôde concluir que as bactérias endofíticas realmente exerceram promoção do crescimento radicular nas plantas.
The society concern with the excessive use of agrochemicals in agriculture to control diseases generates great demand for research with environmentally less aggressive control methods, among them biological control. Utilizing antagonistic relations exerted by microorganisms such as antibiosis, competition, parasitism, predation and resistance induction in plants, offering a wide range of opportunities for the use of microorganisms that are still little known as endophytic microorganisms. The objective of this work was to investigate the biological control potential of endophytic bacteria isolated from cocoa against soil pathogens Fusarium solani, Rhizoctonia solani and Sclerotinia sclerotiorum and their action in promoting the root growth of soybean plants. Twenty-two endophytic bacteria were evaluated in vitro for their antagonistic potential by the culture method paired against phytopathogens, using as parameters: the formation of inhibition halo exerted by bacteria, the size of the pathogen colony and the percentage of inhibition of mycelial growth of the pathogen. The parameters used to evaluate the the control potential of endophytic bactéria on soil fungi and the promotion of root growth in vivo were: the percentage of plant emergence, plant height, percentage of abnormal plants, disease severity, root volume, the fresh mass and dry mass of roots, and the aerial and total part of the plants. There were 9 isolates (TCB 02, TCB 7, TCB 08, TCB 10, TCB 11, TCB 11, TCB 17, TCB 18, TCB 19 and TBC 20) that showed more than 75% inhibition for at least one of the pathogens tested in the experiments in vitro, demonstrating high antagonistic potential. The bacterial isolate TCB 10, identified as Paenibacillus and the bacterial isolate TCB 08, identified as Staphylococcus presented an antagonistic potential for the three phytopathogens. The isolates TCB 17, TCB 18 and TCB 19 presented antagonistic potential for S. sclerotiorum. For the tests with the seed treatment the bacterial isolate TCB 10 presented reduction of the severity of R. solani. It was not possible to conclude that the endophytic bacteria promoted the growth of roots in plants.
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Brewer, Marin Talbot. "Effects of Biological Control and a Ryegrass Rotation on Rhizoctonia Disease of Potato". Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/BrewerMT2003.pdf.
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Ben, Cássio Alberto Vielmo. "Avaliação de cultivares de soja [Glycine max (L.) MERRILL] quanto à tolerância à Rhizoctonia solani". Universidade Federal de Santa Maria, 2015. http://repositorio.ufsm.br/handle/1/5140.
Testo completoAbstract (sommario):
Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorThe objective of this study was to evaluate the genetic resistance of cultivars for the possible damage caused by Rhizoctonia solani in controlled humidity conditions. For this, the work was divided into parts, which began from the get the pathogen identified in the AG-4 anastomosis group, mainly responsible for causing rot the root system and soybean seedling damping-off. Then the spread was performed in laboratory, cultured in petri dishes, and after standing in a culture medium using corn flour, sand and distilled water, which was evaluated inoculum different doses (0, 5, 15, 25, 40g) in order to adjust the conditions for the damage. For the tests in the greenhouse, all experimental units were formed by a polyethylene tray with a capacity of 2.5 L, containing sterile sand 5.5Kg, with additional fertilizers and 80% of field capacity. For the evaluation of inoculum doses opening was arranged in 5 rows in each tray and the treatments applied to the quantities evaluated with 4 repeated, with a repetition of each tray. Two days after inoculation, 50 seeds were sown in each tray. This procedure was performed twice, each time with a different cultivar. We evaluated the germination and the damage to the root system, considered the end that 25g enough to cause damage. Evaluations were carried germination and sanity 40 cultivars which 10 were selected to be used in the final assay. Finally, selected cultivars were evaluated in a greenhouse in two exposure to the pathogen, with and without R. solani, forming a bi factorial (10x2) with 20 treatments. Emergence were evaluated, and tipping in pre emergency, and morphological analyzes, at 28 DAS, plant height was evaluated, fresh and shoot dry, fresh and dry weight of root and root length and volume. For emergencies, there was no significant difference between cultivars without inoculation, however, in inoculum exposure conditions NS 5959 cultivars, TEC 6070 IRGA and ZIP 64 proved superior. To rot in pre-emergency assessments to grow with higher rates was the BMX NIB, with 53.86% of the seeds. For seedling height, the earliest cultivars showed the highest values, with the NS 5959 and V-TOP with the best rates. Both fresh weight as the shoot dry mass did not differ among cultivars and treatments. The analysis of the root system showed better results for cultivars IRGA TEC 6070, NS 5959, CEP 64 and V-TOP to root length, V-TOP and TEC IRGA 6070 for fresh and dry weight of root and root volume. Pathogen confirmation evaluation, the result was positive for all analyzes. In conclusion, you can see very vulnerable cultivars to R. solani, which is an important pathogen found in lowland conditions and can cause major yield losses.
O objetivo deste trabalho foi avaliar a resistência genética de cultivares comerciais quanto aos possíveis danos causados por Rhizoctonia solani em condições de umidade controlada. Para isso o trabalho foi dividido em partes, onde teve início a partir da obtenção do patógeno identificado no grupo de anastomose AG-4, responsável principalmente por causar podridões ao sistema radicular e tombamento de plântulas de soja. Em seguida foi realizada a sua propagação em laboratório, cultivado em placas de petri, e após em um meio de cultura utilizando farinha de milho, areia e água destilada, onde avaliou-se doses de inóculo distintas (0, 5, 15, 25 e 40 g) visando adequar as condições necessárias para obter os danos. Para os ensaios em casa de vegetação, todas as unidades experimentais foram formadas por uma bandeja de polietileno com capacidade para 2,5 L, contendo 5,5Kg de areia estéril, com adubação complementar e com 80% da capacidade de campo. Para a avaliação das doses de inóculo, procedeu-se a abertura de 5 linhas em cada bandeja e aplicou-se os tratamentos com as quantidades avaliadas, com 4 repetição, sendo cada bandeja uma repetição. Dois dias após a inoculação, foram semeadas 50 sementes em cada bandeja. Esse procedimento foi realizado duas vezes, sendo cada vez, com uma cultivar distinta. Avaliou-se a germinação e os danos causados ao sistema radicular, considerado ao final que 25g suficiente para causar danos. Procedeu-se avaliações de germinação e sanidade de 40 cultivares, onde 10 foram selecionadas para serem utilizadas no ensaio final. Por fim, as cultivares selecionadas foram avaliadas em casa de vegetação em duas condições de exposição ao patógeno, com e sem R. solani, formando um esquema bi fatorial (10x2) com 20 tratamentos. Foram avaliadas emergência de plântulas, e tombamento em pré emergência, e para análises morfológicas, aos 28 DAS, avaliou-se altura de plantas, massa fresca e seca da parte aérea, massa fresca e seca de raiz e comprimento e volume radicular. Para a emergência, não houve diferença significativa entre cultivares sem inoculação, porém, em condições de exposição ao inóculo as cultivares NS 5959, TEC IRGA 6070 e CEP 64 mostraram-se superiores. Para avaliações de podridão em pré-emergência, a cultivar com maiores índices foi a BMX PONTA, com 53,86% das sementes. Para altura de plântulas, as cultivares mais precoces apresentaram os maiores valores, sendo a NS 5959 e V-TOP com os melhores índices. Tanto a massa fresca quanto a massa seca da parte aérea não apresentaram diferenças estatísticas entre cultivares e entre tratamentos. Já a análise do sistema radicular mostrou melhores resultados para as cultivares TEC IRGA 6070, NS 5959, CEP 64 e V-TOP para comprimento radicular, V-TOP e TEC IRGA 6070 para massa fresca e seca de raiz e volume de raiz. Em avaliação de confirmação de patógeno, o resultado foi positivo para todas as análises realizadas. Em conclusão, é possível verificar grande vulnerabilidade de cultivares a R. solani, que é um importante patógeno encontrado em condições de várzea e que pode causar grande perdas de produtividade.
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Ceresini, Paulo cezar. "Population biology and genetics of Rhizoctonia solani anastomosis group 3 (AG-3)". NCSU, 2000. http://www.lib.ncsu.edu/theses/available/etd-20001122-164118.
Testo completoAbstract (sommario):
Anastomosis group 3 (AG-3) of Rhizoctonia solani is frequently associated with diseases of potato and tobacco. Although isolates from the two hosts are taxonomically related, previous studies have shown differences in their biology, fatty acid composition, pathogenicity and ribosomal DNA. However, the genetic diversity of populations of R. solani AG-3 from potato and tobacco are not known. In this study, the genetic diversity of field populations of R. solani AG-3 from potato and tobacco in North Carolina were examined using somatic compatibility and amplified fragment length polymorphisms (AFLP). A sample of 32 isolates from potato and 36 from tobacco were paired in all possible combinations on PDA plus activated charcoal and glass slides and examined for somatic interactions. Approximately 5% of tobacco isolates and less than 0.5% of potato isolates were somatically compatible. Twenty-eight and eight distinct somatic compatibility groups (SCG) were identified in the potato and tobacco samples, respectively. AFLP analyses indicated that the potato sample of R. solani AG-3 was more genetically diverse (32 AFLP patterns) than the tobacco sample (26 AFLP patterns). None of the potato or tobacco isolates were somatically compatible or shared a common AFLP pattern. Clones (i.e., cases where two or more isolates were somatically compatible and shared the same AFLP pattern) were identified only in the tobacco sample. Eight clones of R. solani AG-3 from tobacco represented 22% of the total sample. All eight SCG of R. solani AG-3 from tobacco were associated with more than one AFLP pattern. Compatible interactions between potato isolates only occurred between isolates from the same field (two isolates in each of four different fields), with similar but not identical AFLP pattern. For analysis of the population structure of R. solani AG-3 from potato, a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used to identify and differentiate genotypes. A population sample of 104 isolates from five counties in eastern NC was analyzed using polymorphic codominant single-locus PCR-RFLP markers identified after sequencing and screening anonymous DNA from a fungal genomic library. Multilocus genotypes were determined screening isolates using combinations of PCR product/polymorphic enzyme for each locus, generating seven PCR-RFLP markers. There was evidence for high levels of gene flow between populations of R. solani AG-3. The five samples were genetically similar with one another. When data was clone-corrected and samples pooled into one single population from NC, random associations of alleles within and between loci were found for all the loci or pairs of loci, indicating random mating. However, when all genotype were analyzed the observed genotypic diversity deviated from panmixia and alleles within and between loci were not randomly associated. These findings support a model of population structure for R. solani AG-3 on potato that includes both recombination and clonality. This study describes the application of a population genetics-based statistical method for detecting migration in populations of R. solani AG-3 from potato using multilocus PCR-RFLP genotypes. The effect of migration from source populations of the pathogen on potato seed tuber on the magnitude of gene flow with a recipient (soil population) in NC was also examined. Analysis of genetic data indicated that the NC population of R. solani AG-3 has experienced recent migration. There was also an indication of high levels of gene flow between the source and the recipient population. Unidirectional migration from source population(s) followed by establishment of migrant genotypes in the recipient population, through colonization, is postulated to explain the high level of gene flow observed.
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Cooke, Julie A. "Nutritional requirement of wheat in relation to tolerance to Rhizoctonia solani Kühn /". Title page, contents and abstract only, 2000. http://web4.library.adelaide.edu.au/theses/09APSP/09apspc772.pdf.
Testo completo
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Back, Matthew Alan. "The interaction between potato cyst nematodes and Rhizoctonia solani diseases in potatoes". Thesis, Open University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396385.
Testo completoAbstract (sommario):
The soil-borne pathogen Rhizoctonia solani and the potato cyst nematode Globodera rostochiensis are detrimental to the growth and productivity of potato crops in the UK. Previous work has shown that plant parasitic nematodes and fungal pathogens can occasionally interact synergistically to form destructive disease complexes. Furthermore, there is some evidence to suggest that an interaction might exist between G. rostochiensis and R. solani on potato. In order to investigate interactions between G. rostochiensis and R. solani, a series of glasshouse and field experiments were undertaken (2000-2001). In field experiments, plots infested with similar population densities of G. rostochiensis were either uninoculated or inoculated with R. solani. A series of potato plant harvests were undertaken to investigate the effects of nematode infestation on the incidence and severity of R. solani diseases and the associated development of plants. In both experiments, a positive relationship was found between the density of G. rostochiensis juveniles present in potato roots and the incidence of stolons infected by R. solani, 6 weeks after planting. Weaker relationships were found between G. rostochiensis densities and stolon infections at 4 and 8 weeks after planting. In addition, a number of relationships were found between G. rostochiensis infestations and other R. solani disease symptoms, although these were less consistent across the harvest dates. In 2002, the experimental plot design was modified to further investigate the effect of G. rostochiensis on black scurf disease caused by R. solani. However, no relationship was observed between G. rostochiensis infestations and the later development of black scurf on daughter tubersThe glasshouse experiments of this project did not show a direct interaction between G. rostochiensis and R. solani diseases. However, both glasshouse experiments were limited by the method used to infest potting medium with G. rostochiensis. On the basis of results obtained from the field experiment, two controlled environment experiments (2002) were undertaken to investigate the growth rate of R. solani in response to root leachates from potato plants uninfested or infested with G. rostochiensis, at different time intervals after the introduction of nematodes. In addition, the concentration of carbohydrates and nitrogen was determined from the root leachate samples. In both experiments, R. solani isolates were found to have a significantly higher radial growth on media amended with root leachates from G. rostochiensis plants compared to uninfested plants at 12 days after the introduction of nematode treatments. Furthermore, a higher sucrose concentration was detected in root leachates from G. rostochiensis infested plants compared to root leachates from uninfested plants. Since exogenous carbohydrates are known to influence the growth and attraction of R. solani, these results may go some way to explain the interaction found
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Gonçalves, Larissa Aparecida. "Produção e caracterização de amilase secretada por Rhizoctonia solani AG-1 IA /". Ilha Solteira, 2019. http://hdl.handle.net/11449/181158.
Testo completoAbstract (sommario):
Orientador: Paulo Cezar CeresiniResumo: Rhizoctonia solani AG-1 IA é um patógeno habitante do solo que causa doenças em pastagens e plantas cultivadas, em vários estados brasileiros. Para penetrar e colonizar os tecidos do hospedeiro, o microrganismo utiliza enzimas que podem ser de interesse biotecnológico e industrial. O objetivo do presente trabalho foi produzir e caracterizar a α-amilase secretada por R. solani AG-1 IA utilizando produtos e resíduos agroindustriais como substratos para fermentação. Para todos os ensaios foi adotado o processo de cultivo em estado sólio (CES) à temperatura de 25 °C e umidade inicial de 60%. Inicialmente, nove isolados de R. solani provenientes de diferentes hospedeiros (arroz, braquiária e soja) foram comparados quanto à produção amilolítica. As maiores atividades enzimáticas foram proporcionadas pelos isolados TO_022 e MT_SO85, procedentes da cultura da soja. Na etapa seguinte, foi avaliado o efeito do substrato sobre a produção enzimática. Farelo de trigo (12,98 U mL-1; TO_022), farelo de soja (3,97 U mL-1; MT_SO85) e braquiária lavada (4,95 U mL-1; TO_022) induziram eficientemente a produção amilolítica. O perfil de produção enzimática no farelo de trigo, melhor substrato avaliado no cultivo, indicou o tempo de 216 h como o mais apropriado para a obtenção de α-amilases pelo isolado TO_022 (22,14 U mL-1), e 240 h para o isolado MT_SO85 (22,84 U mL-1). Para caracterização físico-química da enzima foi utilizado o extrato enzimático bruto do isolado TO_022. A α-amilase de R. sola... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Rhizoctonia solani AG-1 IA is a soil-borne pathogen that causes diseases in pastures and cultivated plants in several Brazilian states. To penetrate and colonize host tissues, the microorganism uses enzymes that may be of biotechnological and industrial interest. The aim of the present work was to produce and characterize the α-amylase secreted by R. solani AG-1 IA using agroindustrial products and residues as substrates for fermentation. For all the tests, the solid state cultivation process (SSC) at 25 °C and initial humidity of 60% was adopted. Initially, nine isolates of R. solani from different hosts (rice, Brachiaria grass and soybean) were compared for amylolytic production. The major enzymatic activities were provided by the isolates TO_022 and MT_SO85, from the soybean crop. In the next step, the effect of the substrate on the enzymatic production was evaluated. Wheat bran (12.98 U mL-1; TO_022), soybean meal (3.97 U mL-1, MT_SO85) and washed ruzigrass (4.95 U mL-1; TO_022) efficiently induced amylolytic production. The enzymatic production profile in wheat bran, the best substrate evaluated in the culture, indicated the time of 216 h as the most appropriate to obtain α-amylases by the TO_022 isolate (22.14 U mL-1), and 240 h for the isolated MT_SO85 (22.84 U mL-1). For the physicochemical characterization of the enzyme, the crude enzymatic extract of the TO_022 isolate was used. The α-amylase of R. solani TO_022 exhibited maximum activity at 55 °C and pH 5.5, and ma... (Complete abstract click electronic access below)
Mestre
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Alexandre, Samara Marrye Aguiar [UNESP]. "Polissacarídeos da biomassa do basidiomiceto Rhizoctonia solani: extração, purificação e atividade biológica". Universidade Estadual Paulista (UNESP), 2015. http://hdl.handle.net/11449/127823.
Testo completoAbstract (sommario):
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000845926.pdf: 1072676 bytes, checksum: cad2ff92580278b3dac67dc96e267389 (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O fungo Rhizoctonia solani, é um fitopatógeno que ataca diversas culturas, provocando o tombamento de plântulas. Há vários estudos visando o combate deste micro-organismo, no entanto, não há relatos da composição química de sua biomassa. De acordo com a literatura a biomassa fúngica pode ser uma fonte promissora de moléculas para aplicação em ensaios biológicos. A partir disso, um estudo inédito da composição química da biomassa do R. solani, principalmente em relação aos polissacarídeos, foi realizado. O micro-organismo foi cultivado em meio mínimo de Vogel com glucose como fonte de carbono. A biomassa resultante de vários cultivos foi tratada consecutivamente com etanol (1:20 m/v, 78 °C, 12h, 1x), e água destilada a quente (1:20 m/v, 100 °C, 4h, 4x). O extrato aquoso foi submetido a ciclos de congelamento e descongelamento de maneira a separar o material insolúvel da fração solúvel que foi precipitada em etanol e denominada PEH2O (precipitado etanólico do extrato aquoso). A fração solúvel foi analisada por GPC, cujos resultados indicaram a necessidade de purificação adicional. A cromatografia de filtração em gel Sepharose CL-6B, a pressão normal, separou o PEH2O em cinco frações distintas, denominadas de PI a PV, eluídas em ordem decrescente de suas massas moleculares. A análise cromatográfica para verificar o grau de homogeneidade de cada pico (GPC) indicou que tanto PIII quanto PV estavam puros e aptos a serem quimicamente caracterizados. A hidrólise ácida e os resultados das análises de metilação e ressonância magnética nuclear uni e bidimensional mostraram que PIII é uma β-D-glucana com cadeia principal formada por ligações (1→3), (1→6) e parcialmente substituída em O-6 por cadeias laterais β-D-glucopiranosídicas e PV uma fucomanogalactana com a cadeia principal formada por resíduos α-D-galactopiranosídicos (1→6) ligados, parcialmente substituídos em O-2 por unidades...
The Rhizoctonia solani is a phytopathogenic fungus that attacks various crops, causing the tipping of seedlings. There are several studies related to the combat this microorganism, however, no reports of its biomass chemical composition. According to the literature the fungal biomass can be a promising source of molecules for the use in biological studies. Then a novel study of the chemical composition from R. solani biomass, mainly in relation to the polysaccharides, was conducted. The microorganism was grown in Vogel minimal salts medium with glucose as carbon source. Biomass resulting from various cultivations was treated consecutively with ethanol (1:20 w/v), 78 °C, 12h, 1x) and hot distilled water (1:20 w/v, 100 °C, 4h, 4x). The aqueous extract was subjected to freezing and thawing cycles in order to separate the insoluble material. The soluble fraction was precipitated in ethanol and named PEH2O (ethanolic precipitated from aqueous extract). That fraction was analyzed by GPC and the results indicated that an additional purification procedure would be necessary. Gel filtration chromatography on Sepharose CL-6B at normal pressure, separated the PEH2O in five distinct fractions named PI to PV, which eluted in decreasing order of their molecular weight. The chromatographic analysis to verify the homogeneity degree of each peak (GPC) indicated that both PIII as PV were pure and able to be chemically characterized. The results from acid hydrolysis, methylation analysis and uni- and bidimensional nuclear magnetic resonance experiments showed that PIII is a glucan with β-D-Glcp(1→3), (1→6)-linked main chain, partially substituted at O-6 by β-D-Glcp side chains and PV a fucomannogalactan with a main chain composed by (1→6)-linked -D-Galp partially substituted in O-2 by non-reducing end-units of α- L-Fucp and α-D-Manp. Some Galp units from main chain were partially methylated at OH-3. Both...
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Drizou, Fryni. "Elucidating the interaction between Brassica napus and Rhizoctonia solani AG 2-1". Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/49317/.
Testo completoAbstract (sommario):
Brassica napus, oilseed rape (OSR), is a worldwide cultivated crop belonging to the family Brassicaceae, broadly used in crop rotations with cereals. Production is focused on oil for human consumption, biodiesel and feedstock. OSR has undergone intensive breeding for optimization of oil content, disease resistance and augmentation of yields, and today is considered one of the most profitable crops. Nonetheless, oilseed rape is the primary host for the necrotrophic soil-borne pathogen Rhizoctonia solani anastomosis group (AG) 2-1. Infection of seedlings causes damping off disease and decreases crop establishment and yields. AG 2-1 is the most prevalent AG of R. solani in wheat fields in the UK. Currently there is no OSR germplasm resistant to R. solani AG 2-1. Available control methods include cultural practices and chemical seed treatments, which aim to postpone the infection and hence improve crop establishment. Changes in agronomic practices and crop management, including choice of cultivars, tillage, application of fertilisers and pesticides, mean that there is a danger of future outbreaks of diseases that in the past were not considered as major problem. This includes R. solani AG 2-1 which can infect other rotational crops as well and due to its saprophytic nature remains in the fields for years. The aim of the PhD was to elucidate interactions between R. solani AG 2-1 and B. napus, by identifying potential resistant traits and understanding how the pathogen counteracts OSR plant defences. The first objective was to develop and compare different high-throughput screening methods that could be used for the phenotyping of OSR germplasm interactions with R. solani AG 2-1. Four methods were developed and compared: (1) nutrient media plates, (2) compost trays, (3) light expanded clay aggregate (LECA) trays and (4) a hydroponic pouch and wick system. Inoculation of LECA was the most suitable method for screening disease caused by AG 2-1 to OSR germplasm, because it allowed the detection of differences in disease severity between the tested OSR genotypes 5 days post infection (dpi) and also to conduct measurements in whole plants. The second objective was to identify any sources of disease resistance by screening a diversity of OSR germplasm. To start the screening, I selected randomly germplasm from commercial cultivars and parental lines of mapping populations that was available in our seed bank. Overall, the germplasm tested consisted of commercial cultivars, genotypes from diversity sets and a mapping population. All genotypes tested appeared to be susceptible to AG 2-1 infection as shown by high disease levels, reduced emergence and survival. Additionally, I tested if any induced defence responses from exposure to disease could be inherited in the next generation through an epigenetic stress response. However, all progeny plants were also highly susceptible indicating that there was no evidence for transgenerational induction of resistance in this system. The third objective was to gain insight into OSR plant defences when exposed to a combination of attacking organisms, as this often occurs in real field situations. I investigated the role of M. persicae infestation on OSR susceptibility to R. solani AG 2-1. There was no effect of AG 2-1 infection on aphid performance. However, M. persicae infestation resulted in significantly more disease symptoms in B. napus cv. ‘Canard’ plants although there were no significant differences in the amount of fungal DNA. Marker genes LOX3 and MYC2 had an augmented expression under AG 2-1 treatment but were downregulated in plants exposed to both aphids and pathogen. Hence, it appears that aphid infestation induced changes in the jasmonic acid (JA) signalling pathway, which resulted in the increased susceptibility to AG 2-1. In conclusion, the present work provided a new high-throughput screening method suitable to phenotype disease by AG 2-1 in the early seedling stage within a short time period. Unfortunately, the current results confirm previous studies indicating that AG 2-1 is an extremely aggressive isolate to OSR germplasm that lacks genetic resistance. Nonetheless, the observed differences between the germplasm tested in the present work suggest that there are potential tolerant traits. For the first time, the current work provided evidence that M. persicae infestation can negatively affect plant defences against R. solani AG 2-1, through suppression of genes involved in JA signalling. Additionally, it was demonstrated that R. solani AG 2-1 induces the activation of defence mechanism related to both JA and salicylic acid (SA) pathways. Future studies aiming to identify resistant/tolerant traits should screen wider Brassica germplasm, including wild species. Additionally, it will be particularly interesting to explore how R. solani overcomes OSR defences by examining the expression of a broader array of genes involved in plant defence mechanisms.
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Alexandre, Samara Marrye Aguiar. "Polissacarídeos da biomassa do basidiomiceto Rhizoctonia solani : extração, purificação e atividade biológica /". São José do Rio Preto, 2015. http://hdl.handle.net/11449/127823.
Testo completoAbstract (sommario):
Orientador: Maria de Lourdes Corradi Custodio da SilvaBanca: Beatriz Eleutério Goi
Banca: Cesar Augusto Tischer
Resumo: O fungo Rhizoctonia solani, é um fitopatógeno que ataca diversas culturas, provocando o tombamento de plântulas. Há vários estudos visando o combate deste micro-organismo, no entanto, não há relatos da composição química de sua biomassa. De acordo com a literatura a biomassa fúngica pode ser uma fonte promissora de moléculas para aplicação em ensaios biológicos. A partir disso, um estudo inédito da composição química da biomassa do R. solani, principalmente em relação aos polissacarídeos, foi realizado. O micro-organismo foi cultivado em meio mínimo de Vogel com glucose como fonte de carbono. A biomassa resultante de vários cultivos foi tratada consecutivamente com etanol (1:20 m/v, 78 °C, 12h, 1x), e água destilada a quente (1:20 m/v, 100 °C, 4h, 4x). O extrato aquoso foi submetido a ciclos de congelamento e descongelamento de maneira a separar o material insolúvel da fração solúvel que foi precipitada em etanol e denominada PEH2O (precipitado etanólico do extrato aquoso). A fração solúvel foi analisada por GPC, cujos resultados indicaram a necessidade de purificação adicional. A cromatografia de filtração em gel Sepharose CL-6B, a pressão normal, separou o PEH2O em cinco frações distintas, denominadas de PI a PV, eluídas em ordem decrescente de suas massas moleculares. A análise cromatográfica para verificar o grau de homogeneidade de cada pico (GPC) indicou que tanto PIII quanto PV estavam puros e aptos a serem quimicamente caracterizados. A hidrólise ácida e os resultados das análises de metilação e ressonância magnética nuclear uni e bidimensional mostraram que PIII é uma β-D-glucana com cadeia principal formada por ligações (1→3), (1→6) e parcialmente substituída em O-6 por cadeias laterais β-D-glucopiranosídicas e PV uma fucomanogalactana com a cadeia principal formada por resíduos α-D-galactopiranosídicos (1→6) ligados, parcialmente substituídos em O-2 por unidades...
Abstract: The Rhizoctonia solani is a phytopathogenic fungus that attacks various crops, causing the tipping of seedlings. There are several studies related to the combat this microorganism, however, no reports of its biomass chemical composition. According to the literature the fungal biomass can be a promising source of molecules for the use in biological studies. Then a novel study of the chemical composition from R. solani biomass, mainly in relation to the polysaccharides, was conducted. The microorganism was grown in Vogel minimal salts medium with glucose as carbon source. Biomass resulting from various cultivations was treated consecutively with ethanol (1:20 w/v), 78 °C, 12h, 1x) and hot distilled water (1:20 w/v, 100 °C, 4h, 4x). The aqueous extract was subjected to freezing and thawing cycles in order to separate the insoluble material. The soluble fraction was precipitated in ethanol and named PEH2O (ethanolic precipitated from aqueous extract). That fraction was analyzed by GPC and the results indicated that an additional purification procedure would be necessary. Gel filtration chromatography on Sepharose CL-6B at normal pressure, separated the PEH2O in five distinct fractions named PI to PV, which eluted in decreasing order of their molecular weight. The chromatographic analysis to verify the homogeneity degree of each peak (GPC) indicated that both PIII as PV were pure and able to be chemically characterized. The results from acid hydrolysis, methylation analysis and uni- and bidimensional nuclear magnetic resonance experiments showed that PIII is a glucan with β-D-Glcp(1→3), (1→6)-linked main chain, partially substituted at O-6 by β-D-Glcp side chains and PV a fucomannogalactan with a main chain composed by (1→6)-linked -D-Galp partially substituted in O-2 by non-reducing end-units of α- L-Fucp and α-D-Manp. Some Galp units from main chain were partially methylated at OH-3. Both...
Mestre
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Morissette, Danielle. "Characterization of the Stachybotrys elegans' genes regulated during its interaction with Rhizoctonia solani". Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102815.
Testo completoAbstract (sommario):
Stachybotrys elegans is a mycoparasite of the soilborne plant pathogen fungus Rhizoctonia solani. The mycoparasitic activity of S. elegans is correlated with the production of cell wall-degrading enzymes such as chitinases. This study details the cloning and characterization of the cDNA, sechi44, that encodes an extracellular endochitinase. The expression regulation of sechi44 was altered when S. elegans was in interaction with its host, R. solani, and also when the mycoparasite was grown on minimal media amended with different carbon and nitrogen sources. Direct contact with R. solani significantly upregulated sechi44 expression which followed a cyclical pattern suggesting that this gene has a role not only in mycoparasitism, but also in linear growth of the mycoparasite. The addition of high concentrations of glucose and ammonium triggered a decrease of sechi44 expression suggesting that sechi44 is subject to glucose and ammonium repression. In a separate study, several genes (1016 clones) whose transcription was substantially up-regulated during the mycoparasitic interaction were identified using SSH and microarray analysis. Twenty-five percent (261 clones) of these were sequenced and assigned to putative functions. Among them, 15 expressed sequence tags (ESTs) were identified in R. solani whose functions were related to defense while the majority of ESTs were identified in S. elegans and assigned functions related to toxin metabolism, pathogenic process, stress response., multidrug resistance, apoptosis, transport, ATP synthesis, replication, transcription and DNA repair, translation, transduction, protein degradation, and ribosomal protein. The overexpression of 13 selected genes of S. elegans was validated and confirmed using quantitative reverse transcription polymerase chain reaction (QRT-PCR). The temporal gene expression of nine genes was monitored when the mycoparasite was grown on R. solani (host) and Sclerotinia sclerotiorum (non-host) mycelia and sclerotia. Some genes such as seglu, selec, and se151 were completely inhibited by the presence of non-host hyphae suggesting that these genes play an important role during mycoparasitism. Also, the absence of these corresponding transcripts suggests that the non-host produces transcription inhibitors. As expected, gene expression of cytochrome P450 was highly up-regulated early after germination of S. elegans conidia. This is in agreement with our finding in the EST data mining study, in which a role in toxin production was assigned to cytochrome P450.
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Porto, Maria Alice Formiga. "Associação de Fusarium solani, Macrophomina phaseolina e Rhizoctonia solani causando podridão radicular em meloeiro sob efeito de adubos verdes". Universidade Federal Rural do Semi-Árido, 2015. http://bdtd.ufersa.edu.br:80/tede/handle/tede/105.
Testo completoAbstract (sommario):
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Previous issue date: 2015-02-27Conselho Nacional de Desenvolvimento Científico e Tecnológico
The occurrence of root diseases is one of the main reasons of yield loss in melon crop, especially the pathogens that causes root and collar rot, as the fungi Fusarium solani (Mart.) Sacc., Macrophomina phaseolina (Tassi) Gold. and Rhizoctonia solani Kuhn, being observed in muskmelon either alone or associated. The use of crop residues and plant materil, besides the improvement in the physical properties of the soil, also favors microbial activity of the species presents in this environment and affects negatively onpathogens population. Therefore, the objective of this work was to evaluate the associations of F. solani, M. phaseolina and R. solani in the incidence and severity of root rot and fresh and dry weight of muskmelon and verify the effect of green manure in root rot caused by these pathogens alone or associated. The experiment was conducted in two stages, in a greenhouse. The first stage evaluated the association of F. solani, M. phaseolina and R. solani causing root rot in melon, using a randomized block design with 8 treatments (F. solani; M. phaseolina, R. solani, F. solani + M. phaseolina, F. solani + R. solani; M. phaseolina + R. solani, F. solani + M. phaseolina + R. solani; non-infested soil) and 8 repetitions with experimental unit of one pot (3.5 L) with 2 plants. The characteristics evaluated were the incidence of root rot in melon plants at the end of the cycle; disease severity based on a scale notes, and the fresh and dry weight of muskmelon. At the second stage, evaluated the effects of green manure in the association of these pathogens in muskmelon, which was conducted one experiment with Jack beans (Canavalia ensiformis L. DC) and another with Pearl millet (Pennisetum glaucum (L.) R. BR.). The experiments were performed simultaneously in a randomized block design with 8 x 4 factorial {8 types of fungi / association (M. phaseolina, R. solani, F. solani, M. phaseolina + R. solani; M. phaseolina + F. solani, R. solani + F. solani; M. phaseolina + R. solani + F. solani; non-infested soil), 4 forms of management [incorporated, in coverage, polyethylene film (mulching) and without managment]} and 4 repetitions. The characteristics evaluated were the incidence of root rot of melon plants at the end of the cycle, and the fresh and dry weight of muskmelon. The results of disease incidence were submitted to the non-parametric test of Kruskal-Wallis and the fresh and dry weight of muskmelon were analyzed by the Scott-Knott test, both with significance level of 5% of probability (α = 0.05%). At stage 1, the treatment with the three pathogens F. solani, M. phaseolina and R. solani associated resulted in lower incidence of plants with symptoms and was not statistically different from the control. The pathogen R. solani was the least prevalent in the associations. The lowest accumulation of fresh and dry matter happened when the soil was infested with Fusarium solani alone. At stage 2, Jack beans in coverage provided lower incidence of root rot in muskmelon with Fusarium solani alone and in triple association (F. solani +M. phaseolina and R. solani). The use of Pearl millet had no effect on root rot incidence in most treatments. In both experiments (Jack beans andPearl millet), Macrophomina phaseolina was the fungus that prevailed in almost all associations. Jack beans and millet did not increase the fresh and dry weight of muskmelon in most treatments
A ocorrência de doenças radiculares representa uma das principais causas de perda de rendimento na cultura do melão, com destaque para os patógenos causadores das podridões de raízes e colos, como os fungos Fusarium solani (Mart.) Sacc., Macrophomina phaseolina (Tassi) Gold. e Rhizoctonia solani Kuhn, sendo observados no meloeiro tanto de forma isolada quanto associada. A utilização de restos de cultura e material vegetal, além de melhorar as propriedades físicas do solo, favorece a atividade microbiana das espécies presentes neste ambiente e interfere negativamente sobre a população de patógenos. Portanto, objetiva-se com este trabalho avaliar as associações dos patógenos F. solani, M. phaseolina e R. solani na incidência e severidade de podridão radicular e na massa da matéria fresca e seca do meloeiro e verificar o efeito de materiais vegetais na podridão radicular causada por estes patógenos isolados ou associados. O experimento foi conduzido em duas etapas, em casa de vegetação, sendo que na primeira avaliou-se a associação de F. solani, M. phaseolina e R. solani causando podridão radicular em meloeiro, quando foi utilizado o delineamento em blocos casualizados com 8 tratamentos (F. solani; M. phaseolina; R. solani; F. solani + M. phaseolina; F. solani + R. solani; M. phaseolina + R. solani; F. solani + M. phaseolina + R. solani; solo não infestado) e 8 repetições, com unidade experimental de 1 vaso (3,5 L) com duas plantas. As características avaliadas foram: incidência de podridão radicular nas plantas de melão no fim do ciclo, severidade da doença com base em escala de notas, além da matéria fresca e seca das plantas de melão. Na segunda etapa, foi avaliado o efeito de materiais vegetais na associação desses patógenos, também em meloeiro, onde foi realizado um experimento com Feijão-de-porco (Canavalia ensiformis L. DC) e outro com Milheto (Pennisetum glaucum (L.) R. BR.). Os experimentos foram conduzidos simultaneamente, em delineamento experimental de blocos casualizados, com esquema fatorial 8 x 4, sendo 8 tipos de fungos/associação (M. phaseolina; R. solani; F. solani; M. phaseolina + R. solani; M. phaseolina + F. solani; R. solani + F. solani; M. phaseolina + R. solani + F. solani; solo sem inoculação), 4 formas de manejo (incorporado, cobertura, mulching e sem manejo) e 4 repetições. As características avaliadas foram: incidência de podridão radicular nas plantas de melão no fim do ciclo, a massa da matéria fresca e seca das plantas de melão. Os resultados de incidência de doença obtidos foram submetidos ao teste não paramétrico de Kruskal-Wallis e a massa damatéria fresca e seca foram analisados pelo teste de Scott-Knott, ambos com nível de significância a 5% de probabilidade (α = 0,05%). Na etapa 1, o tratamento no qual foram associados três patógenos F. solani, M. phaseolina e R. solani propiciou menor porcentagem de plantas com sintomas da doença e não diferiu estatisticamente da testemunha. O fitopatógeno R. solani foi o que menos prevaleceu nas associações. Quando o solo foi infestado com Fusarium solani, isoladamente, o melão obteve baixo acúmulo de matéria fresca e seca. Na etapa II, o feijão-de-porco em cobertura proporcionoiu menor incidência de podridão radicular do meloeiro quando o Fusarium solani estava sozinho e em associação tripla (F. solani +M. phaseolina e R. solani). A utilização do milheto não apresentou efeito na incidência de podridão radicular na maioria dos tratamentos. Tanto na utilização do feijão-de-porco quanto do milheto, M. phaseolina foi o fungo que prevaleceu na maioria das associações nas quais estava presente. O feijão-de-porco e o milheto não proporcionaram aumento na massa da matéria fresca e seca do meloeiro na maioria dos tratamentos
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Pereira, Jackeline Leite. "Análise da interação entre Phaseolus vulgaris, Trichoderma harzianum ALL 42 e os fungos fitopatogênicos Fusarium solani e Rhizoctonia solani". reponame:Repositório Institucional da UnB, 2012. http://repositorio.unb.br/handle/10482/16489.
Testo completoAbstract (sommario):
Tese (doutorado)—Universidade de Brasília, Departamento de Biologia Molecular, Programa de Pós-graduação em Biologia Celular e Molecular, 2012.Submitted by Ana Cristina Barbosa da Silva (annabds@hotmail.com) on 2014-10-14T12:22:10Z No. of bitstreams: 1 2012_JackelineLeitePereira.pdf: 3652289 bytes, checksum: 11e3d00bc97f96db1c6ae48254de4373 (MD5)
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Este estudo teve como objetivo analisar a interação entre o fungo Trichoderma harzianum ALL-42 isolado de solo do Cerrado e Phaseolus vulgaris, na presença ou ausência dos fungos fitopatogênicos Rhizoctonia solani e Fusarium solani. Foram avaliadas as capacidades de T. harzianum de promover o crescimento, bem como de modular a resposta de defesa e alterar o padrão de expressão de proteínas na planta hospedeira, P. vulgaris. Os feijoeiros cultivados na presença deste isolado mostraram um aumento significativo de 14,29% no tamanho, 17,72% na área foliar e 36,31% no volume radicular, quando comparados às plantas controle. Análises da produção de enzimas relacionadas à resposta de defesa vegetal em folhas em raízes das plantas mostraram que os valores mais significativos de atividade de quitinases em folhas e raizes de feijoeiro, foram detectadas para as plantas cuja interação envolvia o fungo micoparasita T. harzianum e um dos fungos fitopatogênicos, R. solani ou F. solani. Para β 1,3 glucanases, os valores de atividade mais significativos foram detectados em folhas, após 7 dias de cultivo na presença do fungo fitopatogênico R. solani e em raízes, após 14 dias, nesta mesma condição. Valores aumentados da atividade de peroxidases foram detectados nas folhas de plantas cultivadas por 14 dias na presença do isolado de Trichoderma e do fungo fitopatogênico R. solani. Em raízes o aumento nesta atividade foi detectado nas plantas cultivadas apenas na presença do isolado de Trichoderma. A presença do isolado de Trichoderma e dos fungos fitopatogênicos alterou o padrão de expressão dos genes CHT1, GLU, POD6 e LOX1 codificadores de proteínas de defesa, principalmente após 14 e 21 dias de crescimento. Além disto, a presença destes fungos alterou o padrão de expressão de proteínas em folhas e raízes de feijoeiro. Dos ―spots‖ diferencialmente expressos, 80 foram selecionados para identificação por espectrometria de massas utilizando ―Peptide Mass Fingerprint‖, sendo que 29 dos identificados foram retirados de mapas proteômicos de raízes, e 19 de mapas proteômicos de folhas. As proteínas identificadas em suas maioria tem papel na resposta de defesa de plantas, a exemplo da glutationa S – transferase, Cinamoil CoA redutase, serina-treonina quinase, chalcona isomerase, peroxirredoxina, proteínas da família PR-1, e no metabolismo de carboidratos, como, subunidades da Rubisco, anidrase carbônica e gliceraldeído 3- fosfato desidrogenase. Estes resultados sugerem que o isolado de T. harzianum ALL-42 é capaz de promover mudanças no metabolismo da planta, e desencadear ou potencializar a resposta de defesa em feijoeiro comum, quando R. solani e F. solani estão presentes. __________________________________________________________________________________________________ ABSTRACT
The aim of this study was to analyze the interaction between the fungus Trichoderma harzianum ALL-42, which was isolated from the soil of the ―Cerrado‖ biome, and Phaseolus vulgaris in the presence or absence of the phytopathogenic fungi Rhizoctonia solani and Fusarium solani. The growth-promoting capacities of T. harzianum were evaluated, as well as its ability to modulate the defense response and alter the protein expression pattern in the host plant P. vulgaris. Bean plants cultivated in the presence of this isolate showed a significant increase of 14.29% in size, 17.72% in leaf area, and 36.31% in root volume when compared with control plants. Analysis of enzyme production related to the plant defense response in the leaves and roots of the plants showed that the most significant values for kinase activity in the leaves and roots of bean plants were detected for those in which there was an interaction between the microparasitic fungus T. harzianum and one of the phytopathogenic fungi R. solani or F. solani. The most significant values for β-1,3-glucanase activity were detected in the leaves after 7 days of cultivation in the presence of the phytopathogenic fungus R. solani and in the roots after 14 days under the same conditions. Increased values were detected for peroxidase activity in the leaves of plants cultivated for 14 days in the presence of the isolate of Trichoderma and the phytopathogenic fungus R. solani. In the roots, an increase in this activity was detected in plants cultivated only in the presence of the isolate of Trichoderma. The presence of the isolate of Trichoderma and the phytopathogenic fungi altered the expression pattern of the genes CHT1, GLU, POD6, and LOX1 that code for defense proteins, particularly after 14 and 21 days of growth. Furthermore, the presence of these fungi altered the protein expression pattern in the roots and leaves of bean plants. Of the differentially expressed spots, 80 were selected for identification by mass spectrometry using peptide mass fingerprinting. Of those identified, 29 were taken from proteomic maps of the roots and 19 from proteomic maps of the leaves. The majority of the identified proteins play a role in the defense response of the plants, e.g., glutathione S-transferase, cinnamoyl-CoA-reductase, serine-threonine kinase, chalcone isomerase, peroxiredoxin, and proteins of the PR-1 family, and in the metabolism of carbohydrates, such as subunits of Rubisco, carbonic anhydrase, and glyceraldehyde-3-phosphate dehydrogenase. These results suggest that the ALL-42 isolate of T. harzianum is capable of promoting changes in the metabolism of the plant and triggering or potentiating the defense response in the common bean plant when R. solani and F. solani are present.
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Arts, Monique R. "Gene expression of the mycoparasite Stachybotrys elegans during interaction with a fungal host and a hon-host". Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=101835.
Testo completoAbstract (sommario):
The mycoparasite Stachybotrys elegans represents a potential biocontrol agent of Rhizoctonia solani, the causal organism of potato stem canker. The differential expression of two mycoparasitism-induced genes was monitored in S. elegans during interactions with its host, Rhizoctonia solani, and a non-host, Sclerotinia sclerotiorum. Using real-time reverse-transcription polymerase chain reaction (QRT-PCR), comparative analyses demonstrated that hyphal and sclerotial forms triggered different patterns of gene expression in the mycoparasite, as did the presence of the host or non-host. The calmodulin gene did not appear to be involved in conidial germination or appressoria formation of S. elegans. Potential roles of calmodulin during mycoparasitism are suggested, but further studies are required. The expression of the endochitinase-encoding gene, sechi44, was susbstantial only at later stages of interaction with living host sclerotia. Host defense mechanisms probably play a role in regulating sechi44 expression. Knowledge of the genetic mechanisms underlying this mycoparasitic relationship will further our knowledge on the potential use of S. elegans in biocontrol strategies.Le mycoparasite Stachybotrys elegans est un agent potentiel de lutte biologiquepour le contrôle de Rhizoctonia solani, un phytopathogène causant le chancre dela tige et des stolons chez la pomme de terre (Solanum tuberosum). L'expressionde deux gènes induits pendant le mycoparasitisme a été étudiée chez S. elegans,alors que le mycoparasite était en interaction avec son hôte, R. solani, et un nonhôte,Sclerotinia sclerotiorum en utilisant la PCR quantitative en temps réel. Desanalyses comparatives ont démontré que les différentes formes d'hyphes et desc1érotes, ainsi que la présence de l'hôte ou du non-hôte, induisent différentspatrons d'expression. Le gène codant pour la calmodulin (calmodulin) ne semblepas être impliqué dans la germination des conidia ou dans la formation desappressoria chez S. elegans. Des rôles possibles de calmodulin sont suggérés,mais des études plus poussées demeurent nécessaires. L'expression du gènesechi44, codant pour une endochitinase, est importante dans des stades plusavancés du mycoparasitisme sur les sc1érotes vivants de 1 'hôte. Des mécanismesde défense de l'hôte jouent probablement un rôle important dans la régulation del'expression de sechi44. Une meilleure connaissance de la régulation génétiquelors du mycoparasitisme pourrait nous aider à évaluer le potentiel de S. elegansdans des stratégies de biocontrôle.
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Guillemaut, Cécile. "Identification et étude de l'écologie de Rhizoctonia solani, responsable de la maladie de pourriture brune de la betterave sucrière". Lyon 1, 2003. http://www.theses.fr/2003LYO10203.
Testo completoAbstract (sommario):
Rhizoctonia solani est un champignon tellurique responsable de dégâts importants en culture betteravière. L'identification de 311 isolats avec une méthode de type PCR-RFLP, complétée par des tests de pathogénicité a montré que les souches appartenant au groupe d'anastomose 2 subdivision 2 (AG-2-2) étaient responsables des symptômes de pourriture brune en France. La comparaison du potentiel infectieux et de la réceptivité de sols prélevés dans des zones où les betteraves sont saines/malades dans un même champ a montré que R. Solani était présent en faibles densités dans les sols naturels. Sa multiplication est très rapide en présence d'une source nutritionnelle et plus ou moins locale suivant les conditions environnementales. L'espèce végétale cultivée affecte le potentiel infectieux du sol et la sévérité des dégâts sur la culture de betterave suivante. Cela suggère qu'une meilleure gestion de l'assolement et des résidus de culture pourrait diminuer l'inoculum primaire.
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Streeter, Tania C. "Role of Zn nutritional status on infection of Medicago species by Rhizoctonia solani /". Title page, contents and abstract only, 1998. http://web4.library.adelaide.edu.au/theses/09APSP/09apsps915.pdf.
Testo completo
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Ritchie, Faye. "Aspects of the biology, epidemiology and control of Rhizoctonia Solani (Kühn) on potato". Thesis, University of Glasgow, 2006. http://theses.gla.ac.uk/3528/.
Testo completoAbstract (sommario):
Aspects of the biology, epidemiology and control of Rhizoctonia solani from potato were investigated using a range of laboratory and field-based experiments. In vitro experiments revealed nutritional factors including a range of carbon sources, and inorganic and organic nitrogen did not affect significantly mycelial growth or sclerotial germination. Carbon and nitrogen sources including cellobiose, glucose, glycerol and potassium nitrate significantly increased sclerotial biomass production in vitro. Mycelial growth, sclerotial production and germination occurred over a temperature range of 10-30oC, with an optimum of 25oC for both AG 2-1 and AG 3 isolates. Mycelial growth and sclerotial germination occurred at pH 4-9 with an optimum of pH 5.6, whereas sclerotial production occurred between pH 4-6 for AG 2-1 isolates and pH 4-8 for AG 3 isolates. Mycelial growth, sclerotial biomass production and germination declined with decreasing osmotic, matric and soil water potential, with mycelial growth prevented between -3.5 MPa and -4.0MPa on osmotically adjusted media, at -2.0 MPa on metrically adjusted media and -6.3 MPa in soil. Sclerotial production ceased prior to the limits for mycelial growth and germination for all isolates, between -1.5 MPa and -3.5 MPa on osmotically adjusted media and -1.5 MPa on metrically adjusted media. AG 3 isolates produced significantly more well-formed sclerotia during all in vitro experiments compared to the loosely constructed sclerotia produced by AG 2-1 isolates. A pathogenicity bioassay, coupled with staining and microscopic examination of stem tissues, showed all AGs formed infection cushions as a prerequisite to infection, with clear differences in the extent of infection cushion formation and subsequent stem lesion severity. AG 2-1 produced small, infrequent infection cushions, causing stem lesions only 1-2 mm in length which did not increase in size or severity after initial formation.
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Nanayakkara, Chandrika Malkanthi Hewawasam. "Bacterial biocontrol and soil solarization strategies for suppression of Rhizoctonia solani on rice". Thesis, University of Aberdeen, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424985.
Testo completoAbstract (sommario):
Use of known antagonists and antagonistic, endophytic bacteria was investigated to screen a successful antagonist for the fungal strains R. solani AG 2-1, R. solani AG 4 and R. solani AGSL01. Reputed antagonists used in the study; Bacillus subtilis MBI 205, B. subtilis MBI 600, Pseudomonas fluorescens B5 and P. corrugate R. 117 were capable of suppressing the fungus in dual cultures. Manipulation of soil factors to reduce pre-plant density of R. solani sclerotia involved a laboratory experiment followed by two field experiments. In the laboratory study, the effect of constant soil temperatures was investigated by incubating sclerotia at 30, 35, 40, 45 and 50°C. Sclerotia were counted into lots of 100, placed in polyester mesh bags (85 μm pore size, 10 x 10 cm dimension) at depths of 5 and 10 cm in rice field soils contained in plastic containers (20x20x18 cm). Total loss of viability was observed on day 1, day 8 and day 28 at 45°C, 40°C and 35°C, respectively. Loss was even detected within 6.00 h at 50oC. Field experiments of soil solarization (carried out at The Regional Agricultural Research Institute (RARI), Bombuwela, Sri Lanka) were conducted during the fallow periods between the two main cropping seasons in 2003. During the trials, the effect of polythene mulching, straw incorporation and their combined effect on the viability of sclerotia were investigated. Sclerotia (lots of 100) were buried at depths of 5 and 10 cm and the soil temperature was recorded at 8.00, 11.00, 14.00 and 17.00h daily at both depths. During the field trials, at both depths, the effect of treatment over time was noted on percentage recovery and viability of sclerotia (p<0.001). The results showed a drop in mean percentage recovery of less than 50% during the first week of both trials. Germination was markedly reduced to less than 10% by the first week in all the treatments. Depth of burial and straw incorporation had no effect. In solarized plots, a significant increase in soil temperature at both soil depths was observed between 14.00 and 17.00h. Average temperatures of 40°C and 34°C were observed for solarized and non-solarized plots, respectively. The study therefore has identified a practical, low cost and environmentally friendly method of control, and the use of polythene five weeks prior to rice seed sowing is recommended to minimise sheath blight and other diseases caused by similar soil-borne fungal pathogens.
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Rethwisch, Michael D., Mark Reay, Thomas A. Turini e Ron Swan. "Interaction of Cotton Varieties and Rhizoctonia solani: Effects on Resultant Plant Populations, 2005". College of Agriculture, University of Arizona (Tucson, AZ), 2006. http://hdl.handle.net/10150/198195.
Testo completoAbstract (sommario):
Eight varieties were evaluated under field conditions for resultant plant populations after field infection with Rhizoctonia solani. Highest plant populations were noted in Delta and PineLand 454BR, followed by three other Delta and PineLand (DPL) varieties. Stoneville and Phytogen cotton varieties had reduced plant stands compared to DPL varieties at approximately 30 days after planting. DPL 454BR, which had the highest plant population, also had earlier growth and establishment than other varieties which is thought to have helped plant survival. Although all seed was treated with multiple fungicides, seed of DPL varieties was treated with several fungicide active ingredients (thiram, tridimenol) not present on seed from other varieties. Comparative increased stand on DPL varieties may be in part due to plant genetics as well as fungicide. Stand loss was noted in all varieties however. Data indicate that in-furrow application of fungicides or applications to small cotton plants may be necessary for heavier soils under cool and moist early season growing conditions in the low desert.
49
Genzel, Franziska. "The molecular basis of the plant-pathogen interaction of potato and Rhizoctonia solani". Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19404.
Testo completoAbstract (sommario):
Die Kartoffel, eines der wichtigsten Nahrungsmittel weltweit, wird unter anderem von dem Erreger Rhizoctonia solani Kühn befallen. Durch dieses Pathogen hervorgerufene Qualitäts- und Ertragsverminderungen können zu erheblichen ökonomischen Verlusten führen. Da derzeitig verfügbare Bekämpfungsmaßnahmen nur eine eingeschränkte Effektivität aufzeigen, sind alternative Bekämpfungsstrategien dringend notwendig. Der Einsatz resistenter Sorten stellt eine effektive, umweltfreundliche Alternative dar, jedoch ist derzeit nur wenig über die der Resistenz der Kartoffel gegenüber R. solani zugrundeliegenden Mechanismen bekannt. Ziel dieser Arbeit war es, Merkmale aufzufinden, die mit einer erhöhten Feldresistenz der Kartoffel gegenüber R. solani korrelieren und zukünftig als Marker in der Züchtung zur Einschätzung des Resistenzgrads von Sorten genutzt werden können. Auf der Grundlage von Feldversuchen wurden zwei Kartoffelgenotypen mit einem unterschiedlichen Grad der Feldresistenz gegenüber R. solani für vergleichende molekularbiologische und biochemische Analysen ausgewählt. Die Analyse des Expressionsniveaus ausgewählter Abwehrgene zeigte, dass die Kartoffelsorte mit geringerer Anfälligkeit ein konstitutiv höheres Expressionsniveau aufweist als die Sorte mit einer höheren Anfälligkeit. Im Gegensatz zur stärker anfälligen Sorte wurde in Wurzeln und Stängeln der weniger anfälligen Sorte kein erhöhtes Expressionsniveau der Abwehrgene infolge der Infektion mit R. solani festgestellt. Zudem wies die weniger anfällige Sorte höhere Gehalte an α-Chaconin and α-Solanin sowie Nicotiflorin auf. Anhand von in vitro Untersuchungen wurde ein wachstumshemmender Effekt dieser Komponenten auf R. solani festgestellt. Weiterhin wurde ein geringerer Gehalt an R. solani-DNA in den Wurzeln der weniger anfälligen Sorte determiniert. Demnach scheint eine geringere Anfälligkeit der Kartoffel gegenüber diesem Erreger mit einer höheren, präformierten pflanzlichen Immunabwehr korreliert zu sein.Potato, the fourth most important food crop worldwide, is also target of many pests and microbial pathogens including the fungus Rhizoctonia solani Kühn. The infection of potato with this pathogen leads to considerable economic losses. The soil-borne nature, the formation of melanised sclerotia, and the limited efficacy of fungicides impair the control of this pathogen and strengthen the necessity for alternative control measures. A very effective alternative is the use of resistant cultivars. Quantitative differences in the degree of resistance of potato to R. solani have been repeatedly observed in the field. However, until now there is no information available regarding the underlying mechanisms contributing to the resistance level. This thesis aimed at revealing mechanisms in potato which contribute to the manifestation of a certain degree of field resistance to R. solani. Based on the screening of various potato genotypes in field trials, two potato cultivars distinctly differing in the level of resistance to R. solani were selected for further molecular and biochemical analyses. The cultivar with a higher degree of resistance showed higher constitutive expression of defence-related genes. In contrast to the less resistant cultivar, no distinct increase of the defence-gene expression level was detectable upon pathogen infection in this cultivar. Moreover, contents of the glycoalkaloids α-chaconine and α-solanine and of the flavonol nicotiflorin were higher compared to the less resistant cultivar. Using in vitro culture tests, a growth-reducing effect of these compounds on R. solani was confirmed. Concluding, a higher resistance of potato cultivars to R. solani seems to be related to a higher expression level of defence-related genes and to a higher content of plant secondary metabolites. This enhanced constitutive defence level resulted in a lower pathogen colonisation of the plant, thus contributing to a reduced disease severity in the field.
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Barros, Betijane Soares de. "Avaliação da atividade antinociceptiva da fração metanólica obtida a partir da biomassa do fungo endofítico da espécie Rhizoctonia solani". Universidade Federal de Alagoas, 2012. http://repositorio.ufal.br/handle/riufal/933.
Testo completoAbstract (sommario):
The Rhizoctonia is a genus belonging to the Fungi Kingdom, whose representatives live in the soil and act as endophytes of various plants. Among the plants possessing this fungus, deserves the red-pepper tree (Schinus terebinthifolius Raddi), which is popularly used for different purposes, including inflammation. This work describes the antinociceptive and antiinflammatory activity of methanolic fraction obtained from the biomass of the endophytic fungus from Rhizoctonia solani. The methanolic fraction, when administered by intraperitoneal route, was able to reduce the nociception induced by acetic acid for a period of 8 h. In addition, the methanolic fraction increased the lag time measured in the model of thermal nociception, thus suggesting a possible central action. The same substance exhibited antinociceptive activity in formalin test in both phase, neurogenic and inflammatory. In search of a possible mechanism of action, we found that among the pharmacological tools used, only naloxan was able to restore the action of the methanolic fraction, thus suggesting that the substance acts via opioid receptor. In the search for a possible anti-inflammatory effect from this methanol fraction, we used the rat paw edema test and found that this fraction was able to significantly inhibit the paw edema induced by carrageenan and PGE2. Using histamine as an inducer of edema, we note that the methanolic fraction was also antiedematogenic. In this model, the reference drugs indomethacin and promethazine inhibited the edema formation. Together, our results show for the first time that the methanolic fraction obtained from the biomass of the endophytic fungus Rhizoctonia solani has a potent antinociceptive and anti-inflammatory.Conselho Nacional de Desenvolvimento Científico e Tecnológico
A Rhizoctonia é um gênero pertencente ao Reino Fungi, cujos seus representantes habitam o solo e atuam como endofíticos de vários organismos vegetais. Dentre as plantas possuidoras deste fungo, merece destaque a aroeira-vermelha (Schinus terebinthifolius Raddi), que é utilizada popularmente para diferentes finalidades, incluindo inflamação. Este trabalho descreve a atividade antiinflamatória e antinociceptiva da fração metanólica obtida a partir da biomassa do fungo endofítico Rhizoctonia solani. A fração metanólica, quando administrado por via intraperitoneal, foi capaz de reduzir a nocicepção induzida pelo ácido acético por um período de 8 h. Além disso, a fração metanólica aumentou o tempo de latência avaliado no modelo de nocicepção térmica, sugerindo assim uma possível ação central. A mesma substância apresentou atividade antinociceptiva no ensaio de formalina, tanto na fase neurogênica quanto na fase inflamatória. Em busca de um possível mecanismo de ação, verificamos que dentre as ferramentas farmacológicas usadas, apenas a naloxona foi capaz de reverter à ação da fração metanólica, sugerindo assim que a substância age via receptor opióide. Estendendo as análises para uma possível ação antiinflamatória da fração metanólica, utilizamos o ensaio de edema de pata e verificamos que esta fração foi capaz de inibir de modo significativo o edema de pata induzido por carragenina e PGE2. Utilizando-se a histamina como indutor do edema, notamos que a fração metanólica também se mostrou antiedematogênica. Neste modelo, os fármacos de referência indometacina ou prometazina foram capazes de inibir a formação do edema. Juntos, nossos resultados mostram, pela primeira vez, que a fração metanólica obtida a partir da biomassa do fungo endofítico Rhizoctonia solani apresenta uma potente atividade antinociceptiva e antiinflamatória.