Journal articles on the topic 'Sclerotial'
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1
Singh, U. P., B. K. Sarma, D. P. Singh, and Amar Bahadur. "Studies on exudate-depleted sclerotial development in Sclerotium rolfsii and the effect of oxalic acid, sclerotial exudate, and culture filtrate on phenolic acid induction in chickpea (Cicer arietinum)." Canadian Journal of Microbiology 48, no. 5 (May 1, 2002): 443–48. http://dx.doi.org/10.1139/w02-040.
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Exudate depletion from developing sclerotia of Sclerotium rolfsii Sacc. in culture caused reduced size and weight of sclerotia. Germination of exudate-depleted sclerotia was delayed on Cyperus rotundus rhizome meal agar medium when compared with that of control sclerotia. The exudate-depleted sclerotia caused infection in chickpea (Cicer arietinum) plants in a glasshouse. Different temperatures and incubation periods had no effect on the germination ability of the exudate-depleted sclerotia. Oxalic acid, sclerotial exudate, and culture filtrate of S. rolfsii induced the synthesis of phenolic acids, including gallic, ferulic, chlorogenic, and cinnamic acids, as well as salicylic acid, in treated chickpea leaves. Gallic acid content was increased in treated leaves compared with the untreated controls. Maximum induction of gallic acid was seen in both leaves treated with oxalic acid followed by exudate and leaves treated with culture filtrate. Cinnamic and salicylic acids were not induced in exudate-treated leaves. Ethyl acetate fractionation indicated that the sclerotial exudates consisted of gallic, oxalic, ferulic, chlorogenic, and cinnamic acids, whereas the culture filtrate consisted of gallic, oxalic, and cinnamic acids along with many other unidentified compounds.Key words: oxalic acid, phenolic acid, salicylic acid, sclerotial exudate, culture filtrate, Sclerotium rolfsii, sclerotial germination.
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Van_Toor, R. F., J. M. Pay, M. V. Jaspers, and A. Stewart. "Developing tests to determine viability of Ciborinia camelliae (Kohn) sclerotia." New Zealand Plant Protection 53 (August 1, 2000): 147–50. http://dx.doi.org/10.30843/nzpp.2000.53.3668.
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Two methods were developed to assess the viability of Ciborinia camelliae (Kohn) sclerotia for subsequent use in assays of sclerotial parasitisation In the first method external contaminants were removed by washing the sclerotia twice in 135 NaOCl and soaking them in antibiotics Bisected sclerotia grown on potato dextrose agar for 9 days at 20C produced identifiable colonies of C camelliae In the second method sclerotial softness which is proposed as an indicator of decay was measured The compression energy required to push a 276 mm diameter penetrometer with a force of 40 N into a healthy sclerotium gave an indication of sclerotial softness
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Ayed, Fakher, Hayfa Jabnoun-Khiareddine, Rania Aydi-Ben-Abdallah, and Mejda Daami-Remadi. "Effects of pH and Aeration on Sclerotium rolfsii sacc. Mycelial Growth, Sclerotial Production and Germination." International Journal of Phytopathology 7, no. 3 (December 27, 2018): 123–29. http://dx.doi.org/10.33687/phytopath.007.03.2688.
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Sclerotium rolfsii is one of the devastating soilborne fungus responsible for significant plant losses. The effects of pH and aeration on pathogen mycelial growth, sclerotial production and germination were investigated for three Tunisian isolates. Optimal mycelial growth occurred at pH 6 for Sr2 and Sr3 isolates and at pH 6-7 for Sr1. Dry mycelial growth was optimum at pH values ranging between 4 and 7. Sclerotial initiation started on the 3rd day of incubation at all pH values tested and mature sclerotia were formed after 6 to 12 days. Optimal sclerotial production was noted at pH 5. The dry weight of 100 sclerotia varied depending on isolates and pH and occurred at pH range 4-7. At pH 9, mycelial growth, sclerotial production and dry weight of 100 sclerotia were restricted. The optimum sclerotial germination, noted after 24 h of incubation, varied depending on isolates and pH and occurred at pH 4-9. Mycelial growth was optimum in aerated plates with a significant isolates x aeration treatments interaction. Sclerotial initiation occurred at the 3rd day of incubation and mature sclerotia were observed after 6-9 days. Sclerotial development was very slow in completely sealed plates and dark sclerotia were produced only after 15 days of incubation. The highest sclerotial yields were noted in aerated plates. The highest dry weight of 100 sclerotia for Sr1 isolate was recorded in ½ sealed, no sealed and completely sealed plates, while for Sr2, it was noted in ½ and ⅔ sealed plates. For Sr3, the maximum dry weight of 100 sclerotia was recorded in ½, ⅔ and completely sealed plates. Germination of S. rolfsii sclerotia, after 24 h of incubation, did not vary significantly depending on aeration treatments and ranged from 90 to 100% for all isolates.
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Harel, A., R. Gorovits, and O. Yarden. "Changes in Protein Kinase A Activity Accompany Sclerotial Development in Sclerotinia sclerotiorum." Phytopathology® 95, no. 4 (April 2005): 397–404. http://dx.doi.org/10.1094/phyto-95-0397.
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Sclerotia of Sclerotinia sclerotiorum are pigmented, multihyphal structures that play a central role in the life and infection cycles of this pathogen. Sclerotial formation has been shown to be affected by increased intracellular cAMP levels. Cyclic AMP (cAMP) is a key modulator of cAMP-dependent protein kinase A (PKA) and the latter may prove to play a significant role in sclerotial development. Therefore, we monitored changes in relative PKA activity levels during sclerotial development. To do so, we first developed conditions for near-synchronous sclerotial development in culture, based on hyphal maceration and filtering. Relative PKA activity levels increased during the white-sclerotium stage in the wild-type strain, while low levels were maintained in nonsclerotium-producing mutants. Furthermore, applying caffeine, an inducer of PKA activity, resulted in increased relative PKA activity levels and was correlated with the formation of sclerotial initial-like aggregates in cultures of the non-sclerotium-producing mutants. In addition, low PKA activities were found in an antisense smk1 strain, which exhibits low extracellular-signal-regulated kinase (ERK)-type mitogen-activated protein kinase (MAPK) activity, and does not produce sclerotia. The changes in PKA activity, as well as the abundance of phosphorylated MAPKs (ERK-like as well as p38-like) that accompany sclerotial development in a distinct developmental phase manner represent a potential target for antifungal intervention.
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Littley, E. R., and J. E. Rahe. "Sclerotial morphogenesis in Sclerotium cepivorum in vitro." Canadian Journal of Botany 70, no. 4 (April 1, 1992): 772–78. http://dx.doi.org/10.1139/b92-098.
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Sclerotial ontogeny, maturation, and aging in Sclerotium cepivorum are described using light and scanning electron microscopy. On potato dextrose agar, the mycelium spread, branching irregularly. Six days after inoculation sclerotial initials appeared, formed by hyphae branching and looping. From 6 to 8 days, the number and size of initials increased, and mucilagenous material appeared. By day 9, hyphal bundles formed in the mycelium. Between 9 and 11 days, spherical forms developed and the sclerotia grew. By day 12, an acellular matrix appeared, and to day 18 this matrix progressively obscured the surface hyphae and became black. A layer of ovoid rind cells developed at the surface. To examine the reduced survival of laboratory-produced compared with field-collected sclerotia, sclerotia from a variety of sources and conditions were compared. In general, the rind of sclerotia aged in dry conditions had a broken, irregular appearance versus fresh sclerotia or sclerotia aged under moist, axenic conditions. Sclerotia aged dry developed 1 to 4 layers of rind cells, while sclerotia kept moist developed only 1 or 2 layers. The structural and survival differences between laboratory-produced and natural sclerotia are attributable to differences in the moisture conditions under which they matured and aged. Key words: Sclerotium cepivorum, white rot, morphogenesis, sclerotia.
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Mila, A. L., and X. B. Yang. "Effects of Fluctuating Soil Temperature and Water Potential on Sclerotia Germination and Apothecial Production of Sclerotinia sclerotiorum." Plant Disease 92, no. 1 (January 2008): 78–82. http://dx.doi.org/10.1094/pdis-92-1-0078.
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The effects of fluctuating soil temperature and water potential on sclerotial germination and apothecial production by Sclerotinia sclerotiorum were investigated in growth chamber experiments. In the temperature experiments, temperature fluctuations of 4, 8, 12, and 16°C around a median of 20°C, and a constant of 20°C, were tested. Daily temperature fluctuations of 8°C resulted in highest levels of sclerotial germination and apothecial production. The earliest appearance of apothecia occurred in the 8°C fluctuation treatment, 24 days after the start of the experiment. Sclerotia in the 12°C fluctuation treatment germinated last; its first sclerotium germinated 44 days after experiment initiation. For the soil water potential experiments, constant saturation (approximately –0.001 MPa) and three levels of soil water potential fluctuation from saturation—“low” (–0.03 to –0.04 MPa), “medium” (–0.06 to –0.07 MPa), and “high” (–0.09 to –0.1 MPa)—were tested. Constant saturation yielded the highest number of germinated sclerotia and apothecia. All soil water potential fluctuations were detrimental to sclerotial germination and apothecial production, with sclerotial germination under fluctuating moisture conditions less than a tenth of that occurring under constant saturation. The first sclerotium in the constant saturation treatment germinated in 35 days; however, 76 days were required in the high soil water potential fluctuation treatment.
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Willetts, H. J., Suzanne Bullock, Elizabeth Begg, and N. Matsumoto. "The structure and histochemistry of sclerotia of Typhula incarnata." Canadian Journal of Botany 68, no. 10 (October 1, 1990): 2083–91. http://dx.doi.org/10.1139/b90-273.
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The results of a study of the ultrastracture and histochemistry of sclerotia of the psychrophilic snow mold Typhula incarnata indicated some unique features. These included the following: a continuous, pigmented layer external to the rind of the sclerotium; medullary hyphal walls that contained large amounts of β-1,3 glucans; conspicuous fibrils distributed through medullary hyphal walls; the absence of an extensive extracellular matrix characteristic of sclerotia of many mesophilic fangi; large, usually single, phenol-rich bodies in rind cells; and medullary hyphae that either contained several phenol bodies or protein bodies and polyphosphate granules, some of which were contained within protein bodies. These features are compared with those of sclerotia of mesophilic fungi, and their possible significance is discussed. Key words: sclerotia, sclerotial morphology, sclerotial histochemistry, snow mold, Typhula.
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Ayed, Fakher, Hayfa Jabnoun-Khiareddine, Rania Aydi-Ben Abdallah, and Mejda Daami-Remadi. "Effect of Different Carbon and Nitrogen Sources on Sclerotium rolfsii sacc. Mycelial Growth and Sclerotial Development." International Journal of Phytopathology 9, no. 1 (April 30, 2020): 17–27. http://dx.doi.org/10.33687/phytopath.009.01.3066.
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In vitro studies were conducted on Potato Dextrose Agar using different carbon (C) and nitrogen (N) sources to evaluate their effects on the mycelial growth, and the sclerotial development of three Tunisian Sclerotium rolfsii Sacc. isolates. Radial growth was optimum on basal medium supplemented with ammonium chloride (0.48 gram of nitrogen per liter (g of N.L-1)) as N source but was restricted on L-Arginine and completely inhibited on ammonium acetate amended media (0.48 g N.L-1). Sclerotial initiation occurred from the 3rd to the 12th day of incubation for all tested isolates. Potassium nitrate was the most suitable N source for sclerotial formation whereas sclerotial development was completely inhibited on ammonium acetate amended medium. Optimal sclerotial germination was recorded using L-Arginine (78-80%) followed by L-Asparagine (46-94%) and ammonium chloride (46-88%) as N sources. Nevertheless, the lowest sclerotial germination rate was noted on sodium nitrate and ammonium acetate amended media. As for C sources (16 gram of carbon per liter (g of C.L-1)), optimal radial growth occurred using D-mannitol for Sr1 and Sr2 isolates and maltose for Sr3, but no mycelial growth was recorded using sodium citrate for all isolates. All C sources tested, except sodium citrate, were suitable for sclerotial formation, production, and germination. Mature sclerotia became brownish after 6 to 12 days of incubation and sclerotial production was highest using D-mannitol, maltose, and D-glucose, depending on isolates used, as C sources. Optimal germination of sclerotia was noted using D-glucose, D-mannitol and maltose for Sr1 isolate, maltose for Sr2 and D-glucose and maltose for Sr3. It was concluded that N and C sources are both important factors for the growth of S. rolfsii and its survival.
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McLean, K. L., G. E. Harper, C. M. Frampton, and A. Stewart. "Dormancy of Sclerotium cepivorum sclerotia in New Zealand soils." New Zealand Plant Protection 58 (August 1, 2005): 245–50. http://dx.doi.org/10.30843/nzpp.2005.58.4288.
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Sclerotium cepivorum sclerotia require incubation in soil to overcome constitutive dormancy a condition where the sclerotia will not germinate even when stimulated In Trial 1 artificial onion extract diallyl disulphide (DADS) was used to stimulate sclerotial germination of laboratory produced sclerotia after 1 2 and 3 month conditioning periods when incubated in two different soil types The results showed that soil type and fungal isolate did not affect dormancy and that approximately 16 33 and 21 of the sclerotia germinated after 1 2 and 3 month conditioning periods respectively In Trial 2 DADS significantly increased sclerotial germination compared with the control after 2 3 4 5 and 6 month conditioning periods Sclerotia required 6 months in soil before high rates of germination occurred (>89) when stimulated When a natural population of sclerotia (8 weeks old) (Trial 3) was exposed to DADS 51 of the population germinated compared with 21 in the control (Plt;0001)
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Kohn, Linda M., and Douglas J. Grenville. "Ultrastructure of stromatal anamorphs in the Sclerotiniaceae." Canadian Journal of Botany 67, no. 2 (February 1, 1989): 394–406. http://dx.doi.org/10.1139/b89-055.
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As part of comparative anatomical, histochemical, and ultrastructural studies of stromata in the Sclerotiniaceae, mature stromata produced in vitro by 11 species representing six genera and one form-genus were examined using transmission electron microscopy. Sclerotial-stromatal taxa were Sclerotinia sclerotiorum, S. trifoliorum, S. minor, Sclerotium cepivorum, Botrytis cinerea, B. porri, Monilinia fructicola, and Myriosclerotinia borealis. Substratal-stromatal taxa were Sclerotinia homoeo-carpa, Rutstroemia sydowiana, and Lambertella subrenispora. Three types of rind were observed: a living cellular rind, a dead cellular rind, and a stromatal rind. Sclerotial species were distinguished from stromatal species not only by the rind type, but also by the confluent extracellular matrix around cortical and medullary cell walls. Presence of lacunae in this matrix distinguished Sclerotinia spp. and M. borealis from Botrytis spp. and Monilinia fructicola. Rind, cortical, and medullary cells contained abundant storage vacuoles in most taxa. The distribution and proportion of organelles to storage vacuoles differed among taxa. Plugged septal pores with associated Woronin bodies were similar among the taxa where they were observed. Sclerotia of Sclerotium cepivorum, which has no known teleomorph, are ultrastructurally most like sclerotia of Sclerotinia or Botrytis anamorphs of Botryotinia species. Substratal stromata of S. homoeocarpa showed unusually complex cellular organization. Sclerotial stromata of M. fructicola contained unusual storage vacuoles with heterogeneous contents.
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Clark, C. A. "Influence of volatiles from healthy and decaying sweet potato storage roots on sclerotial germination and hyphal growth of Sclerotium rolfsii." Canadian Journal of Botany 67, no. 1 (January 1, 1989): 53–57. http://dx.doi.org/10.1139/b89-008.
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Volatiles released from sweet potato storage root tissue infected by different sweet potato storage root pathogens stimulated eruptive germination of sclerotia of Sclerotium rolfsii but did not influence the direction of hyphal growth on agarose. Volatiles from healthy sweet potato storage root tissue did not affect percent hyphal or eruptive germination of sclerotia of S. rolfsii but stimulated directional growth of hyphae toward the healthy tissue. In laboratory experiments, the frequency of infection of sweet potato stem segments by S. rolfsii on the surface of natural soil was increased when sclerotia were incubated in the presence of decaying sweet potato storage root tissue. Incidence of sclerotial blight lesions on sprouts in plant beds was increased in the presence of roots infected by Fusarium solani or Erwinia chrysanthemi. Volatiles from decaying sweet potato mother roots may predispose sweet potatoes to sclerotial blight.
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Shrestha, Utsala, Mary E. Dee, Bonnie H. Ownley, and David M. Butler. "Anaerobic Soil Disinfestation Reduces Germination and Affects Colonization of Sclerotium rolfsii Sclerotia." Phytopathology® 108, no. 3 (March 2018): 342–51. http://dx.doi.org/10.1094/phyto-04-17-0152-r.
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Growth chamber and field studies were conducted with organic amendment mixtures of carbon (C) and nitrogen (N) at C:N ratios 10:1, 20:1, 30:1, and 40:1 and amendment rates of C at 2, 4, 6, and 8 mg/g of soil (C:N ratio 30:1) to evaluate anaerobic soil disinfestation (ASD) effects on germination and colonization of Sclerotium rolfsii. In the growth chamber, sclerotial germination was reduced in all ASD treatments regardless of C:N ratio (0.6 to 8.5% germination) or amendment rate (7.5 to 46%) as compared with nonamended controls (21 to 36% and 61 to 96%, respectively). ASD treatment increased Trichoderma spp. colonization of sclerotia, with consistently higher colonization in ASD treatments with amendment rates of C at 2 or 4 mg/g of soil (>87% colonization) compared with nonamended controls (<50% colonization). In the 2014 field study, sclerotial germination was reduced by 24 to 30% in ASD treatments when compared with the nonamended control. Sclerotial colonization by Trichoderma spp. was predominant; however, other potential mycoparasites (i.e., Aspergillus spp., Fusarium spp., zygomycetes, and other fungi) were present in the field study. Amendment C:N ratios in the range of 10:1 to 40:1 were equally effective in reducing sclerotial germination and enhancing colonization by potentially beneficial mycoparasites of sclerotia.
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Shim, M.-Y., and J. L. Starr. "Effect of Soil pH on Sclerotial Germination and Pathogenicity of Sclerotium rolfsii1." Peanut Science 24, no. 1 (January 1, 1997): 17–19. http://dx.doi.org/10.3146/i0095-3679-24-1-5.
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Abstract The effect of soil pH on sclerotial germination and pathogenicity of two isolates of Sclerotium rolfsii on peanut was examined. Sclerotial germination for both isolates was greater (P ≤ 0.05) in acidic soil than at alkaline pHs. Similarly, percentage of peanut stems infected by S. rolfsii in greenhouse tests was greater at soil pH 5.6 than at alkaline soil pHs (P ≤ 0.05), but disease did develop at soil pH 8.7 and 9.8. In contrast to a previous in vitro study, these data confirm that sclerotia of S. rolfsii will germinate and initiate disease at soil pH > 7.0.
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Horowitz Brown, S., R. Zarnowski, W. C. Sharpee, and N. P. Keller. "Morphological Transitions Governed by Density Dependence and Lipoxygenase Activity in Aspergillus flavus." Applied and Environmental Microbiology 74, no. 18 (July 25, 2008): 5674–85. http://dx.doi.org/10.1128/aem.00565-08.
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ABSTRACT Aspergillus flavus differentiates to produce asexual dispersing spores (conidia) or overwintering survival structures called sclerotia. Results described here show that these two processes are oppositely regulated by density-dependent mechanisms and that increasing the cell density (from 101 to 107 cells/plate) results in the lowest numbers of sclerotial and the highest numbers of conidial. Extract from spent medium of low-cell-density cultures induced a high-sclerotium-number phenotype, whereas high-cell-density extract increased conidiation. Density-dependent development is also modified by changes in lipid availability. Exogenous linoleic acid increased sclerotial production at intermediate cell densities (104 and 105 cells/plate), whereas oleic and linolenic acids inhibited sclerotium formation. Deletion of Aflox encoding a lipoxygenase (LOX) greatly diminished density-dependent development of both sclerotia and conidia, resulting in an overall increase in the number of sclerotia and a decrease in the number of conidia at high cell densities (>105 cells/plate). Aflox mutants showed decreased linoleic acid LOX activity. Taken together, these results suggest that there is a quorum-sensing mechanism in which a factor(s) produced in dense cultures, perhaps a LOX-derived metabolite, activates conidium formation, while a factor(s) produced in low-density cultures stimulates sclerotium formation.
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Ray, K., K. Sen, P. P. Ghosh, A. Roy Barman, R. Mandal, M. De Roy, and S. Dutta. "Dynamics of Sclerotium rolfsii as influenced by different crop rhizosphere and microbial community." Journal of Applied and Natural Science 9, no. 3 (September 1, 2017): 1544–50. http://dx.doi.org/10.31018/jans.v9i3.1399.
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This study was carried out with the aim of evaluating pathogenicity of Sclerotium rolfsii to different crops influenced by different crop rhizosphere microbes and their population dynamics. Napier was found to be non-preferred host against S. rolfsii pathogen. Among the seven tested crops in micro-plot study, highest level of induction of sclerotial population was observed in groundnut and cow peas (21.81 and 20.06 numbers of sclerotia /100 g of soil, respectively), whereas, reduction in sclerotial number was observed in napier, maize and sorghum plots. S. rolfsii induced damping off was found to be significantly positively correlated with average sclerotial population irrespective of plant cover even at 1% level of significance (r = 0.985) and among the microbiological parameters, FDA was found to be significantly negatively correlated with damping off disease percentage at 5% level of significance (r = - 0.830). Therefore, Napier may be the potential crop to be incorporated in the sequence of rice/vegetable based cropping system in West Bengal for management of this dreaded pathogen.
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Liu, Bo, Haode Wang, Zhoujie Ma, Xiaotong Gai, Yanqiu Sun, Shidao He, Xian Liu, Yanfeng Wang, Yuanhu Xuan, and Zenggui Gao. "Transcriptomic evidence for involvement of reactive oxygen species in Rhizoctonia solani AG1 IA sclerotia maturation." PeerJ 6 (June 18, 2018): e5103. http://dx.doi.org/10.7717/peerj.5103.
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Rhizoctonia solani AG1 IA is a soil-borne fungal phytopathogen that can significantly harm crops resulting in economic loss. This species overwinters in grass roots and diseased plants, and produces sclerotia that infect future crops. R. solani AG1 IA does not produce spores; therefore, understanding the molecular mechanism of sclerotia formation is important for crop disease control. To identify the genes involved in this process for the development of disease control targets, the transcriptomes of this species were determined at three important developmental stages (mycelium, sclerotial initiation, and sclerotial maturation) using an RNA-sequencing approach. A total of 5,016, 6,433, and 5,004 differentially expressed genes (DEGs) were identified in the sclerotial initiation vs. mycelial, sclerotial maturation vs. mycelial, and sclerotial maturation vs. sclerotial initiation stages, respectively. Moreover, gene ontology (GO) and kyoto encyclopedia of genes and genomes (KEGG) analyses showed that these DEGs were enriched in diverse categories, including oxidoreductase activity, carbohydrate metabolic process, and oxidation-reduction processes. A total of 12 DEGs were further verified using reverse transcription quantitative PCR. Among the genes examined, NADPH oxidase 1 (NOX1) and superoxide dismutase (SOD) were highly induced in the stages of sclerotial initiation and maturation. In addition, the highest reactive oxygen species (ROS) production levels were detected during sclerotial initiation, and enzyme activities of NOX1, SOD, and catalase (CAT) matched with the gene expression profiles. To further evaluate the role of ROS in sclerotial formation, R. solani AG1 IA was treated with the CAT inhibitor aminotriazole and H2O2, resulting in the early differentiation of sclerotia. Taken together, this study provides useful information toward understanding the molecular basis of R. solani AG1 IA sclerotial formation and maturation, and identified the important role of ROS in these processes.
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Jarvis, W. R., and J. A. Traquair. "Sclerotia of Aspergillus aculeatus." Canadian Journal of Botany 63, no. 9 (September 1, 1985): 1567–72. http://dx.doi.org/10.1139/b85-217.
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Sclerotial development in Aspergillus aculeatus is described for the first time. The sclerotium originates as a knot of interwoven hyphae. The mature sclerotium has a rind of flattened hyphae, below which are two cortical layers and a medulla. The outer cortical layer has isodiametric cells and the inner layer has somewhat radially elongated polyhedral cells. The thick walls of the cortical cells are perforated by simple septal pores. The medulla comprises a loosely interwoven mass of hyphae. Sclerotia remain pale luteous.
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Insell, James P., N. P. A. Huner, W. Jay Newsted, and R. B. van Huystee. "Light microscopic and polypeptide analyses of sclerotia from mesophilic and psychrophilic pathogenic fungi." Canadian Journal of Botany 63, no. 12 (December 1, 1985): 2305–10. http://dx.doi.org/10.1139/b85-329.
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The structure and polypeptide composition of sclerotia of three mesophilic pathogenic fungi, Sclerotinia sclerotiorum, Sclerotium rolfsii, and Botrytis cinerea, and one psychrophilic snow mold, Myriosclerotinia borealis, were compared. The sclerotia of S. sclerotiorum and B. cinerea were black, round, hard structures which were composed of three areas: the rind, the cortex, and the medulla. Both the cortical and medullary areas of these sclerotia exhibited intensely stained inclusions. In contrast, sclerotia of M. borealis were not present as discrete entities but coalesced near the central point of inoculation. These black sclerotial masses were composed of thin-walled, pseudoparenchymal cells tightly packed together to form two distinct areas: a rind and a medullarylike region. No inclusions were evident in the medulla of cells of M. borealis sclerotia. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of sclerotial extracts of mesophilic fungi indicated the presence of major polypeptides. The polypeptide complement of B. cinerea contained a single, major polypeptide with an apparent molecular mass of 33 to 36 kDa. Similarly, sclerotia of S. sclerotiorum contained one major polypeptide of approximately 36 kDa in addition to one minor polypeptide of about 18 kDa. However, sclerotia of S. rolfsii contained a major polypeptide of about 16 kDa. Sclerotia of M. borealis contained a major polypeptide of 32 to 36 kDa and a minor polypeptide of about 16 kDa.
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Wang, Dan, Junfan Fu, Rujun Zhou, Zibo Li, Yujiao Xie, Xinran Liu, and Yueling Han. "Formation of sclerotia inSclerotinia ginsengand composition of the sclerotial exudate." PeerJ 6 (November 23, 2018): e6009. http://dx.doi.org/10.7717/peerj.6009.
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BackgroundSclerotinia ginsengis a major devastating soil-borne pathogen of ginseng that can cause irreparable damage and large economic losses. This pathogen produces sclerotia, which are among the most persistent resting structures produced by filamentous fungi. The production of an exudate is a common feature of sclerotial development.MethodsS. ginsengwas cultured on 10 different media and the following parameters were measured: mycelial growth rate (mm/day), initial formation time of exudate droplets, total quantity of exudate, number of sclerotia per dish, and sclerotial fresh/dry weight. The composition of the sclerotial exudate was analyzed using four methods (high performance liquid chromatography, gas chromatography-mass spectrometry, flame atomic absorption spectrometry, and Nessler’s reagent spectrophotometry).ResultsWe found that PDA was the optimal medium for exudate production, while SDA medium resulted in the highest mycelial growth rate. The earliest emergence of exudate droplets from sclerotia was on OA-YE and V8 media. The largest amount of sclerotia and the smallest sclerotia were produced on V8 medium. The maximum and minimum dry/fresh weight were obtained on MEA medium and V8 medium, respectively. The exudate contained organic acids (oxalic acid, gallic acid, ferulic acid, vanillic acid, caffeic acid, and tannic acid), carbohydrates (inositol, glucose, and trehalose), various ions (potassium, sodium, and magnesium), and ammonia.DiscussionThe functions of the identified compounds are discussed within the context of pathogenicity, sclerotial development, and antimicrobial activity. Our findings provide information about the production of sclerotia and the composition of sclerotial exudate that may be useful to develop strategies to control this disease.
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McLean, K. L., and A. Stewart. "Infection sites of Sclerotium cepivorum on onion roots." New Zealand Plant Protection 53 (August 1, 2000): 118–21. http://dx.doi.org/10.30843/nzpp.2000.53.3662.
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Onion (Allium cepa) root infection by Sclerotium cepivorum was examined in two glasshouse bioassays In the first bioassay the effect of sclerotial depth was examined Sclerotia placed at 1 10 and 20 cm depths in soil filled planter bags germinated and infected onion roots at 5 7 and 13 weeks after planting respectively The second bioassay determined that the severity of infection varied when sclerotia were placed at the stem base along the length of a root and at the root tip After 22 weeks a greater (P
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Matsumoto, Naoyuki, and Akitoshi Tajimi. "Life-history strategy in Typhula incarnata and T. ishikariensis biotypes A, B, and C as determined by sclerotium production." Canadian Journal of Botany 66, no. 12 (December 1, 1988): 2485–90. http://dx.doi.org/10.1139/b88-337.
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The life-history strategies of Typhula incarnata and T. ishikariensis, the snow mold fungi, were studied in culture experiments. Radial mycelial growth at 0 °C, a temperature at which they thrive under natural conditions, was about half that of growth at the near-optimal temperature, 10 °C. However, when the colonies were covered with unsterile soil, mycelial growth at 0 °C was much greater than at 10 °C. Sclerotium production by T. incarnata was rapid in the latter half of the culture period, and sclerotium maturation was promoted by selected fungi. Typhula incarnata produced sclerotia frequently along the junction with colonies of selected fungi. Typhula ishikariensis biotype A produced the highest percent sclerotial biomass. Sclerotium maturation, i.e., pigmentation, was not stimulated by the selected fungi, but sclerotium production was moderately frequent in dual cultures with them. Typhula ishikariensis biotypes B and C produced the lowest percent sclerotial biomass. Their sclerotium maturation was rapid but not stimulated by the selected fungi. These findings suggest that although these snow mold fungi are, as a whole, stress tolerant, T. incarnata is relatively ruderal, T. ishikariensis biotype A is typically stress tolerant, and T. ishikariensis biotypes B and C are adapted to habitats with high stress and high disturbance.
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Mahr, Naseer Ahmed. "COMPARATIVE EFFICACY OF TEN COMMERCIAL FUNGICIDES FOR THE CONTROL OF RHIZOCTONIA SOLANI, THE CAUSE OF BLACK SCURF DISEASE OF POTATO." Plant Protection 5, no. 3 (December 30, 2021): 149–56. http://dx.doi.org/10.33804/pp.005.03.3930.
Full textAbstract:
Black scurf disease of potato caused by Rhizoctonia solani is one of the major problems causing considerable yield losses throughout the world. The control of R. solani is mainly based on the application of fungicides. Therefore, in the present study, ten fungicides belonging to different groups were evaluated for their in vitro effectiveness against R. solani. Highly significant inhibitory effects of fungicides were recorded on mycelial growth, sclerotial production, and germination of sclerotia of R. solani. In the in vitro test, the sensitivity of R. solani was found to vary greatly with the fungicides and their concentrations. The mycelial growth of R. solani was found to be the most sensitive to Antracol, Benlate, Captan, Dithane M-45, and Ridomil while the least sensitive to Polyram Combi. An intermediate sensitivity of the fungus was noticed to Daconil, Brassicol, Bavistin, and Vitavex. Sclerotial production by the fungus was the most sensitive to Ridomil and Benlate. At 50 ppm concentration, Benlate and Ridomil completely inhibited the sclerotial production. Dithane M-45 and Captan reduced the production of sclerotia greater than Deconil, Brassicol, and Bavistin. The least effective fungicide in reducing sclerotial production was Polyram Combi. Similarly, the most effective fungicide in reducing sclerotial germination was Benlate. The fungicides, Ridomil and Dithane M-45 showed an intermediate effect on the germination of sclerotia while Daconil and Captan proved to be the least effective fungicides in sclerotial germination of R. solani.
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Rollins, Jeffrey A., and Martin B. Dickman. "Increase in Endogenous and Exogenous Cyclic AMP Levels Inhibits Sclerotial Development in Sclerotinia sclerotiorum." Applied and Environmental Microbiology 64, no. 7 (July 1, 1998): 2539–44. http://dx.doi.org/10.1128/aem.64.7.2539-2544.1998.
Full textAbstract:
ABSTRACT Growth and development of a wild-type Sclerotinia sclerotiorum isolate were examined in the presence of various pharmacological compounds to investigate signal transduction pathways that influence the development of sclerotia. Compounds known to increase endogenous cyclic AMP (cAMP) levels in other organisms by inhibiting phosphodiesterase activity (caffeine and 3-isobutyl-1-methyl xanthine) or by activating adenylate cyclase (NaF) reduced or eliminated sclerotial development in S. sclerotiorum. Growth in the presence of 5 mM caffeine correlated with increased levels of endogenous cAMP in mycelia. In addition, incorporation of cAMP into the growth medium decreased or eliminated the production of sclerotia in a concentration-dependent manner and increased the accumulation of oxalic acid. Inhibition of sclerotial development was cAMP specific, as exogenous cyclic GMP, AMP, and ATP did not influence sclerotial development. Transfer of developing cultures to cAMP-containing medium at successive time points demonstrated that cAMP inhibits development prior to or during sclerotial initiation. Together, these results indicate that cAMP plays a role in the early transition between mycelial growth and sclerotial development.
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McLaren, D. L., H. C. Huang, S. R. Rimmer, and E. G. Kokko. "Ultrastructural studies on infection of sclerotia of Sclerotinia sclerotiorum by Talaromyces flavus." Canadian Journal of Botany 67, no. 7 (July 1, 1989): 2199–205. http://dx.doi.org/10.1139/b89-279.
Full textAbstract:
Talaromyces flavus is a destructive hyperparasite capable of infecting sclerotia of Sclerotinia sclerotiorum. Examinations of sclerotia by transmission electron microscopy at 3, 7, and 12 days after inoculation revealed that hyphae of T. flavus penetrated the rind cell walls directly. Etching of the cell walls at the penetration site was evident. This suggests that wall-lysing enzymes may be involved in the process of infection. Hyphae of T. flavus grew both intercellularly and intracellularly throughout the rind, cortical, and medullary tissues. Ramification of the hyperparasite in the sclerotium resulted in destruction and collapse of sclerotial tissues.
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Newsted, W. J., and N. P. A. Huner. "Major polypeptides associated with differentiation in psychrophilic fungi." Canadian Journal of Botany 65, no. 2 (February 1, 1987): 233–41. http://dx.doi.org/10.1139/b87-033.
Full textAbstract:
Major polypeptides were observed upon one-dimensional sodium dodecyl sulfate gel electrophoresis of sclerotial extracts of the following psychrophiles: Myriosclerotinia borealis, Coprinus psychromorbidus, Typhula idahoensis, and Typhula incarnata. In general, the number, molecular mass, and relative proportion of these major sclerotial polypeptides varied considerably from species to species. Furthermore, in the case of M. borealis, the major sclerotial polypeptide did not appear to be an artifact of culturing conditions since a major polypeptide of similar molecular mass was also present in sclerotia of M. borealis collected from the field. Generally, the major sclerotial polypeptides were visible in the sclerotial initials but were not apparent in the vegetative hyphae. Thus, these major sclerotial polypeptides appear to be expressed as a function of sclerotial development. Electrophoresis of protein extracts of T. idahoensis and T. incarnata initially solubilized either in sodium dodecyl sulfate or urea sample buffer indicated that the type of denaturant initially used had a profound influence on the relative proportions of the major polypeptides and the overall polypeptide profile. Isoelectric focusing of sclerotial extracts indicated that the isoelectric points of the major sclerotial polypeptides of M. borealis ranged from 6.2 to 6.7, whereas the values of the major sclerotial polypeptides of the other three species were basic and ranged from 7.0 to 7.7.
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Kohn, Linda M., and Douglas J. Grenville. "Anatomy and histochemistry of stromatal anamorphs in the Sclerotiniaceae." Canadian Journal of Botany 67, no. 2 (February 1, 1989): 371–93. http://dx.doi.org/10.1139/b89-054.
Full textAbstract:
As part of comparative studies of stromata in the Sclerotiniaceae, mature sclerotial and substratal stromata produced in vitro by 19 species, and 1 form-species, representing 13 genera and 1 form-genus, were examined using light microscopy and histochemical staining. Sclerotial-stromatal taxa were Sclerotinia sclerotiorum, S. trifoliorum, S. minor. Sclerotium cepivorum, Botrytis cinerea, B. porri, Dumontinia tuberose, Ciborinia erythronii, Myriosclerotinia dennisii, M. borealis, Monilinia fructicola, and Stromatinia gladioli. Substratal-stromatal taxa were Lambertella subrenispora, Lanzia luteovirescens, Rutstroemia sydowiana, Stromatinia gladioli, Ovulinia azaleae, Sclerotinia homoeocarpa, Scleromitrula shiraiana, and Ciboria acerina. Histochemical staining, particularly 0.05% toluidine blue O in benzoate buffer at pH 4.4, was found to be useful in demarcating the zones within stromata: rind, cortex, and medulla. All sclerotia contained extensive reserves of carbohydrates in thick cell walls and copious extracellular matrix, while protein bodies were usually the major cytoplasmic storage reserve. A group of saprophytic, substratal isolates had thin medullary cell walls and less extracellular matrix, and did not store protein but stored large deposits of lipid in cytoplasm. A group of phytopathogenic, substratal-stromatal isolates appeared to be transitional, with anatomical features and extensive cytoplasmic protein body reserves suggesting that they produce indeterminate sclerotial stromata rather than true substratal stromata.
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McLean, K. L., M. Madsen, and A. Stewart. "The effect of Coniothyrium minitans on sclerotial viability of Sclerotinia sclerotiorum and Ciborinia camelliae." New Zealand Plant Protection 57 (August 1, 2004): 67–71. http://dx.doi.org/10.30843/nzpp.2004.57.6891.
Full textAbstract:
The effect of Coniothyrium minitans on Sclerotinia sclerotiorum and Ciborinia camelliae sclerotial viability was determined on three different substrates sand soil and sawdust using fully factorial repeat experiments (Trials 1 and 2) In Trial 1 C minitans significantly reduced the number of viable S sclerotiorum sclerotia in sand (48) and sawdust (0) but not in soil (60) compared with the untreated sclerotia (92 64 and 88 respectively) after 8 weeks Although C minitans had no effect on C camelliae sclerotial viability the sawdust only treatment reduced viability to 0 after 4 weeks In the repeat experiment (Trial 2) C minitans had no effect on S sclerotiorum or C camelliae sclerotial viability although C camelliae sclerotial viability was again significantly reduced in the sawdust control treatment (812) compared with the sand and soil control treatments (>84) Coniothyrium minitans has some potential for biocontrol of S sclerotiorum but not of C camelliae Sawdust may be an option for use as an under plant mulch for control of C camelliae
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Liu, Bo, Zhoujie Ma, Xiaotong Gai, Yanqiu Sun, Yanfeng Wang, Shidao He, and Zenggui Gao. "Analysis of putative sclerotia maturation-related gene expression in Rhizoctonia solani AG1-IA." Archives of Biological Sciences 70, no. 4 (2018): 647–53. http://dx.doi.org/10.2298/abs180106026l.
Full textAbstract:
Rhizoctonia solani AG1-IA (R. solani AG1-IA) is a major soil-borne fungal pathogen of maize that causes significant yield losses in all maize-growing regions worldwide. The sclerotium produced by R. solani AG1-IA can overwinter in grass roots or diseased plants and infect crops the following year. The molecular mechanism underlying sclerotium formation in R. solani is poorly understood. In this study, we constructed the cDNA library of the R. solani AG1-IA pathogenic strain WF-9, from which 329 high-quality expressed sequence tags (ESTs) were obtained. Of the 250 clustered unigenes, 12 genes were selected for further expression analysis during the three stages of sclerotial growth (mycelium, initiation of sclerotium, and maturation of sclerotium). The results of expression analysis support the previously suggested roles of chitin synthase D and exo-beta-1,3-glucanase in facilitating sclerotial growth through preservation of water content and energy. In addition, cytochrome P450, NADPH oxidase, catalase (CAT), acyl-CoA oxidase 1 (ACOX1), mitogen-activated protein kinase (MAPK), mitogen-activated protein kinase HOG1 (HOG 1), and the G-protein ? subunit play important roles in balancing reactive oxygen species (ROS) levels during sclerotial development. The findings of this study can help understand the molecular mechanism of sclerotial development further.
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Chen, Changbin, Arye Harel, Rena Gorovoits, Oded Yarden, and Martin B. Dickman. "MAPK Regulation of Sclerotial Development in Sclerotinia sclerotiorum Is Linked with pH and cAMP Sensing." Molecular Plant-Microbe Interactions® 17, no. 4 (April 2004): 404–13. http://dx.doi.org/10.1094/mpmi.2004.17.4.404.
Full textAbstract:
Sclerotial development is fundamental to the disease cycle of the omnivorous broad host range fungal phytopathogen Sclerotinia sclerotiorum. We have isolated a highly conserved homolog of ERK-type mitogen-activated protein kinases (MAPKs) from S. sclerotiorum (Smk1) and have demonstrated that Smk1 is required for sclerotial development. The smk1 transcription and MAPK enzyme activity are induced dramatically during sclerotiogenesis, especially during the production of sclerotial initials. When PD98059 (a specific inhibitor of the activation of MAPK by MAPK kinase) was applied to differentiating cultures or when antisense expression of smk1 was induced, sclerotial maturation was impaired. The smk1 transcript levels were highest under acidic pH conditions, suggesting that Smk1 regulates sclerotial development via a pH-dependent signaling pathway, involving the accumulation of oxalic acid, a previously identified pathogenicity factor that functions at least in part by reducing pH. Addition of cyclic AMP (cAMP) inhibited smk1 transcription, MAPK activation, and sclerotial development. Thus, S. sclerotiorum can coordinate environmental signals (such as pH) to trigger a signaling pathway mediated by Smk1 to induce sclerotia formation, and this pathway is negatively regulated by cAMP.
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Wong, A. L., and H. J. Willetts. "Polyacrylamide-gel Electrophoresis of Enzymes during Morphogenesis of Sclerotia of Sclerotinia sclerotiorum." Microbiology 81, no. 1 (January 1, 2000): 101–9. http://dx.doi.org/10.1099/00221287-81-1-101.
Full textAbstract:
Succinate dehydrogenase (SDH) and glucose-6-phosphate dehydrogenase (Glu-6-PDH) from Sclerotinia sclerotiorum (Lib.) de Bary were moderately active in submerged mycelium while in non-sclerotial aerial mycelium arylesterase and acid phosphatase were very active. In sclerotial initials, glyceraldehyde-3-phosphate dehydrogenase (Gly-3-PDH) and SDH were at their highest level of activity, Glu-6-PDH and phosphogluconate dehydrogenase (PGDH) were moderately active, laccase activity increased markedly, and tyrosinase was detected for the first time, its activity being moderate. In young compacting sclerotia, the activities of Glu-6-PDH and PGDH increased, Gly-3-PDH and SDH showed lowered activities, and laccase activity decreased. Suppression of the glycolytic Krebs-cycle pathway and the stimulation of the pentose phosphate pathway seem important during the compaction and maturation of sclerotia. Tyrosinase may be involved in sclerotial initiation.
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Mischke, Sue. "Mycoparasitism of selected sclerotia-forming fungi by Sporidesmium sclerotivorum." Canadian Journal of Botany 76, no. 3 (March 1, 1998): 460–66. http://dx.doi.org/10.1139/b98-019.
Full textAbstract:
Sporidesmium sclerotivorum Uecker, Ayers, & Adams is mycoparasite of sclerotia with potential for biocontrol. Sclerotia of fungi in the sclerotial lineage of the Sclerotiniaceae, including species of Sclerotinia, Botrytis, Amphobotrys, and Monilinia, stimulated germination of macroconidia of Sp. sclerotivorum. The mycoparasite readily colonized sclerotia of Sclerotinia spp. and Amphobotrys ricini (Buchwald) Hennebert both in soil and in vitro. Sclerotia of Botrytis spp. were parasitized only occasionally, and some Sclerotiniaceae were not parasitized. The limits on the ability of Sp. sclerotivorum to parasitize sclerotia support its classification as fastidious. Not even the first step in mycoparasitism, germination of Sp. sclerotivorum macroconidia, was triggered by sclerotia of fungi outside of the family. Amphobotrys ricini, the causal agent of gray mold of castor bean (Ricinus communis L.), is a newly recognized host of Sp. sclerotivorum, and sclerotia of this pathogen were destructively colonized by the mycoparasite.Key words: Amphobotrys ricini, biocontrol, host-parasite interaction, Sclerotiniaceae, Sclerotium cepivorum, signal.
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Garber, R. K., and P. J. Cotty. "Formation of Sclerotia and Aflatoxins in Developing Cotton Bolls Infected by the S Strain of Aspergillus flavus and Potential for Biocontrol with an Atoxigenic Strain." Phytopathology® 87, no. 9 (September 1997): 940–45. http://dx.doi.org/10.1094/phyto.1997.87.9.940.
Full textAbstract:
Aspergillus flavus can be divided into the S and L strains on the basis of sclerotial morphology. On average, S strain isolates produce greater quantities of aflatoxins than do L strain isolates. Sclerotia of the S strain were observed in commercial seed cotton from western Arizona. Greenhouse tests were performed to better define sclerotial formation in developing bolls. Eight S strain isolates were inoculated into developing bolls via simulated pink bollworm exit holes. All eight isolates formed sclerotia on locule surfaces, and seven of eight isolates produced sclerotia within developing seed. Boll age at inoculation influences formation of sclerotia. More sclerotia formed within bolls that were less than 31 days old at inoculation than in bolls older than 30 days at inoculation. Frequent formation of sclerotia during boll infection may both favor S strain success within cotton fields and increase toxicity of A. flavus-infected cottonseed. Atoxigenic A. flavus L strain isolate AF36 reduced formation of both sclerotia and aflatoxin when coinoculated with S strain isolates. AF36 formed no sclerotia in developing bolls and was more effective at preventing S strain isolates than L strain isolates from contaminating developing cottonseed with aflatoxins. The use of atoxigenic L strain isolates to prevent contamination through competitive exclusion may be particularly effective where S strain isolates are common. In addition to aflatoxin reduction, competitive exclusion of S strain isolates by L strain isolates may result in reduced overwintering by S strain isolates and lower toxicity resulting from sclerotial metabolites.
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Hao, J. J., K. V. Subbarao, and J. M. Duniway. "Germination of Sclerotinia minor and S. sclerotiorum Sclerotia Under Various Soil Moisture and Temperature Combinations." Phytopathology® 93, no. 4 (April 2003): 443–50. http://dx.doi.org/10.1094/phyto.2003.93.4.443.
Full textAbstract:
Sclerotial germination of three isolates each of Sclerotinia minor and S. sclerotiorum was compared under various soil moisture and temperature combinations in soils from Huron and Salinas, CA. Sclerotia from each isolate in soil disks equilibrated at 0, -0.03, -0.07, -0.1, -0.15, and -0.3 MPa were transferred into petri plates and incubated at 5, 10, 15, 20, 25, and 30°C. Types and levels of germination in the two species were recorded. Petri plates in which apothecia were observed were transferred into a growth chamber at 15°C with a 12-h light-dark regime. All retrievable sclerotia were recovered 3 months later and tested for viability. Soil type did not affect either the type or level of germination of sclerotia. Mycelial germination was the predominant mode in sclerotia of S. minor, and it occurred between -0.03 and -0.3 MPa and 5 and 25°C, with an optimum at -0.1 MPa and 15°C. No germination occurred at 30°C or 0 MPa. Soil temperature, moisture, or soil type did not affect the viability of sclerotia of either species. Carpogenic germination of S. sclerotiorum sclerotia, measured as the number of sclerotia producing stipes and apothecia, was the predominant mode that was affected significantly by soil moisture and temperature. Myceliogenic germination in this species under the experimental conditions was infrequent. The optimum conditions for carpogenic germination were 15°C and -0.03 or -0.07 MPa. To study the effect of sclerotial size on carpogenic germination in both S. minor and S. sclerotiorum, sclerotia of three distinct size classes for each species were placed in soil disks equilibrated at -0.03 MPa and incubated at 15°C. After 6 weeks, number of stipes and apothecia produced by sclerotia were counted. Solitary S. minor sclerotia did not form apothecia, but aggregates of attached sclerotia readily formed apothecia. The number of stipes produced by both S. minor and S. sclerotiorum was highly correlated with sclerotial size. These results suggest there is a threshold of sclerotial size below which apothecia are not produced, and explains, in part, why production of apothecia in S. minor seldom occurs in nature.
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Smith, V. L., S. F. Jenkins, Z. K. Punja, and D. M. Benson. "Survival of sclerotia of Sclerotium rolfsii: Influence of sclerotial treatment and depth of burial." Soil Biology and Biochemistry 21, no. 5 (1989): 627–32. http://dx.doi.org/10.1016/0038-0717(89)90055-2.
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Harel, A., S. Bercovich, and O. Yarden. "Calcineurin Is Required for Sclerotial Development and Pathogenicity of Sclerotinia sclerotiorum in an Oxalic Acid-Independent Manner." Molecular Plant-Microbe Interactions® 19, no. 6 (June 2006): 682–93. http://dx.doi.org/10.1094/mpmi-19-0682.
Full textAbstract:
Sclerotinia sclerotiorum is a necrotrophic, omnivorous plant pathogen with worldwide distribution. Sclerotia of S. sclerotiorum are pigmented, multihyphal structures that play a central role in the life and infection cycles of this pathogen. Calcineurin, a Ser/Thr phosphatase linked to several signal-transduction pathways, plays a key role in the regulation of cation homeostasis, morphogenesis, cell-wall integrity, and pathogenesis in fungi. We demonstrate that calcineurin expression in S. sclerotiorum is altered in a phase-specific manner during sclerotial development. Inhibition of calcineurin by FK506, cysclosporin A, or inducible antisense calcineurin expression impaired sclerotial development at the prematuration phase and increased germination of preformed sclerotia. Induction of antisense calcineurin expression in S. sclerotiorum resulted in reduced pathogenesis on tomato and Arabidopsis. However, secretion of oxalic acid, a key virulence factor of S. scle-rotiorum, was not altered. Inhibition of calcineurin conferred a reduction in cell wall β-1,3-glucan content and increased sensitivity to cell-wall-degrading enzymes and to the glucan synthase inhibitor caspofungin. Thus, calcineurin plays a major role in both sclerotial development and pathogenesis of S. sclerotiorum and, most likely, other phyto-pathogens.
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Nepal, Achala, and Luis E. del Río Mendoza. "Effect of Sclerotial Water Content on Carpogenic Germination of Sclerotinia sclerotiorum." Plant Disease 96, no. 9 (September 2012): 1315–22. http://dx.doi.org/10.1094/pdis-10-11-0889-re.
Full textAbstract:
The relationship between moisture content and carpogenic germination (CG) of Sclerotinia sclerotiorum sclerotia and the dynamics of sclerotial water imbibition were studied in a controlled environment. The study was conducted using laboratory-produced sclerotia from seven S. sclerotiorum isolates. The quantity and rate of water imbibition by three sizes of sclerotia was determined gravimetrically in silty clay, sandy loam, and sandy soils maintained at 100, 75, 50, and 25% of soil saturation and in distilled water. Smaller sclerotia imbibed water at a significantly faster rate (P = 0.05) than larger sclerotia in water and in soil at all saturation percentages. When buried in soil, small, medium, and large sclerotia were fully saturated within 5, 15, and 25 h, respectively, in all three soil types and moisture percentages. The effect of sclerotia moisture content on CG was evaluated on sclerotia maintained at 95 to 100, 70 to 80, 40 to 50, and 20 to 30% of their water saturation capacity using cool mist humidifiers. Sclerotial moisture content significantly influenced CG (P = 0.05). Maximum CG was observed on fully saturated sclerotia, while no CG was observed below 70 to 80% of saturation. These findings help explain S. sclerotiorum's ability to produce apothecia in soils with relatively low moisture levels.
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Matsumoto, Naoyuki, and Akitoshi Tajimi. "Continuous variation within isolates of Typhula ishikariensis bio types B and C associated with habitat differences." Canadian Journal of Botany 68, no. 8 (August 1, 1990): 1768–73. http://dx.doi.org/10.1139/b90-228.
Full textAbstract:
Isolates of the snow mold fungus, Typhula ishikariensis, were collected from seven localities in northern Japan where snow cover conditions differ. The isolates were identified as T. ishikariensis biotype B, which produces large sclerotia, biotype C with smaller sclerotia, and large sclerotial and intermediate forms. Mating experiments with tester monokaryons indicated that all populations were related. Populations from localities with deep, persistent snow cover produced larger sclerotia, which germinated more readily carpogenically (biotype B and the large sclerotial form) than those from localities where snow cover was shorter and intermittent (biotype C). The aggressiveness of the former was more variable, whereas the latter was without exception aggressive. There was no apparent correlation between growth rate at 0 °C and duration of snow cover. It was concluded that biotype C has been selected for localities with ephemeral snow cover, but that biotypes B and C and the related forms do not form distinct populations and should be regarded as a single taxon.
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Huang, H. C., C. Chang, and G. C. Kozub. "Effect of temperature during sclerotial formation, sclerotial dryness, and relative humidity on myceliogenic germination of sclerotia of Sclerotinia sclerotiorum." Canadian Journal of Botany 76, no. 3 (March 1, 1998): 494–99. http://dx.doi.org/10.1139/b98-016.
Full textAbstract:
A study was conducted to determine the effect of sclerotial dryness, temperature during sclerotia formation, and relative humiditiy during incubation on myceliogenic germination of sclerotia of two isolates of Sclerotinia sclerotiorum (Lib.) De Bary. In the absence of exogenous nutrients, sclerotia germinated more readily at 100% RH than at 95% RH or lower. Desiccation of sclerotia is an important factor affecting myceliogenic germination and hyphal growth. At high humidity, either in an atmosphere with 100% RH or on moist sand, desiccant-dried sclerotia germinated readily and produced vigorous hyphal growth that often developed into colonies. On the other hand, fresh, untreated sclerotia germinated less readily and produced limited growth of hyphae that rarely developed into colonies. There was generally no effect of temperature at which sclerotia formed on germination. The incidence of seed rot and seedling wilt of sunflower was significantly (p < 0.05) higher when desiccant-dried sclerotia were used as inoculum rather than fresh sclerotia.Key words: Sclerotinia sclerotionum, sclerotia, myceliogenic germination, sclerotinia wilt of sunflower, relative humidity.
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Chitrampalam, P., T. A. Turini, M. E. Matheron, and B. M. Pryor. "Effect of Sclerotium Density and Irrigation on Disease Incidence and on Efficacy of Coniothyrium minitans in Suppressing Lettuce Drop Caused by Sclerotinia sclerotiorum." Plant Disease 94, no. 9 (September 2010): 1118–24. http://dx.doi.org/10.1094/pdis-94-9-1118.
Full textAbstract:
Field experiments were conducted over 2 years in Yuma, AZ, and Holtville, CA, to establish the relationship between soil sclerotium density of Sclerotinia sclerotiorum and the incidence of lettuce drop on different lettuce (Lactuca sativa) types under different irrigation systems, and to determine the efficacy of the biocontrol agent Coniothyrium minitans (Contans) against S. sclerotiorum on crisphead lettuce at varied sclerotium densities under different irrigation systems. There was no significant interaction of irrigation (overhead sprinkler versus furrow) with either sclerotium density or with biocontrol treatment. Lettuce drop incidence was lowest in romaine lettuce compared with crisphead or leaf lettuce at all soil sclerotium densities. There was a significant positive correlation between the sclerotial density and the percent disease incidence. Disease incidence in plots infested with 2 sclerotia/m2 of bed was not significantly higher than in control plots regardless of lettuce type. However, plots infested with 40 or 100 sclerotia/m2 of bed revealed a significantly higher disease incidence over the control in all lettuce types. A single application of Contans at planting significantly reduced the incidence of lettuce drop in all lettuce types even under high disease pressure. There were no significant differences between recommended (2.2 kg/ha) and high (4.4 kg/ha) application rates of Contans or between one or two applications of the product.
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Menzies, J. G. "The reactions of Canadian spring wheat genotypes to inoculation with Claviceps purpurea, the causal agent of ergot." Canadian Journal of Plant Science 84, no. 2 (April 1, 2004): 625–29. http://dx.doi.org/10.4141/p03-086.
Full textAbstract:
Ergot, caused by Claviceps purpurea, can be a detrimental pathogen of wheat because the sclerotia of this fungus are toxic to animals and humans. The purpose of this work was to determine if currently registered Canadian wheat cultivars and experimental wheat lines differ in their reactions to C. purpurea and to determine if different classes of wheat [Canadian Western Red Spring (CWRS), Canadian Prairie Spring (CPS), Canadian Western Extra Strong (CWES), Canadian Western Soft White Spring (CWSWS), and Canadian Western Amber Durum (CWAD)] differ in their levels of resistance. Fifty-four wheat genotypes from different western Canadian classes of wheat were inoculated with a mixture of six isolates of C. purpurea and assessed for the number of sclerotia produced per spike and rated for sclerotial size produced and the amount of honeydew produced. In general, CWAD wheats produced significantly fewer sclerotia per spike and the CWSWS wheats had significantly smaller sclerotia. None of the classes differed in honeydew production. One CWAD genotype, 9260B-173A, had the fewest sclerotia, and the lowest ratings for sclerotial size, and amount of honeydew produced compared to the other wheat genotypes tested. Key words: Hexaploid wheat, durum wheat, Triticum turgidum var. durum, T. aestivum, ergot, Claviceps purpurea, resistance, sclerotia size, honeydew
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Chitrampalam, P., B. M. Wu, S. T. Koike, and K. V. Subbarao. "Interactions Between Coniothyrium minitans and Sclerotinia minor Affect Biocontrol Efficacy of C. minitans." Phytopathology® 101, no. 3 (March 2011): 358–66. http://dx.doi.org/10.1094/phyto-06-10-0170.
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Coniothyrium minitans, marketed as Contans, has become a standard management tool against Sclerotinia sclerotiorum in a variety of crops, including winter lettuce. However, it has been ineffective against lettuce drop caused by S. minor. The interactions between C. minitans and S minor were investigated to determine the most susceptible stage in culture to attack by C. minitans, and to determine its consistency on S minor isolates belonging to four major mycelial compatibility groups (MCGs). Four isolates of S. minor MCG 1 and 5 each from MCGs 2 and 3 and one from MCG 4 were treated in culture at purely mycelial, a few immature sclerotial, and fully mature sclerotial phases with a conidial suspension of C. minitans. Sclerotia from all treatments were harvested after 4 weeks, air dried, weighed, and plated on potato dextrose agar for recovery of C. minitans. S. minor formed the fewest sclerotia in plates that received C. minitans at the mycelial stage; C. minitans was recovered from nearly all sclerotia from this treatment and sclerotial mortality was total. However, the response of MCGs was inconsistent and variable. Field experiments to determine the efficacy of C. minitans relative to the registered fungicide, Endura, on lettuce drop incidence and soil inoculum dynamics were conducted from 2006 to 2009. All Contans treatments had significantly lower numbers of sclerotia than Endura and unsprayed control treatments, and drop incidence was as low as in Endura-treated plots (P > 0.05). Although the lower levels of lettuce drop in Contans treatments were correlated with significantly lower levels of sclerotia, the lower levels of lettuce drop, despite the presence of higher inoculum in the Endura treatment, was attributable to the prevention of infection by S. minor. A useful approach to sustained lettuce drop management is to employ Contans to lower the number of sclerotia in soil and to apply Endura to prevent S. minor infection within a cropping season.
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Madhavi, G. Bindu, S. L. Bhattiprolu, and V. Bali Reddy. "Effect of Various Plant Extracts on Dry Root Rot of Chillies Caused by Sclerotium rolfsii." Journal of Horticultural Sciences 6, no. 2 (December 31, 2011): 156–58. http://dx.doi.org/10.24154/jhs.v6i2.426.
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Eight different plant extracts were evaluated in vitro against Sclerotium rolfsii causing dry root rot in chillies. Among these, leaf extract of neem (Azadirachta indica) caused maximum inhibition of mycelial growth (80.74%), followed by periwinkle Vinca rosea (78.8%) and bottlebrush (Callistemon, 74.8%) respectively. Sclerotial production was inhibited to an extent of 11% and the inhibition caused was maximum with neem extract, followed by Polyalthia longifolia and V. rosea extracts. Though sclerotial germination was inhibited by 30% to 95% in various treatments, the most effective treatment was that of neem leaf extract (95%), followed by ginger extract (92%).
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Zhou, Yingjun, Na Li, Jingyi Yang, Long Yang, Mingde Wu, Weidong Chen, Guoqing Li, and Jing Zhang. "Contrast Between Orange- and Black-Colored Sclerotial Isolates of Botrytis cinerea: Melanogenesis and Ecological Fitness." Plant Disease 102, no. 2 (February 2018): 428–36. http://dx.doi.org/10.1094/pdis-11-16-1663-re.
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Botrytis cinerea usually produces grayish mycelia and conidia as well as black-colored sclerotia (BS) due to accumulation of melanin. An isolate (XN-1) of B. cinerea producing orange-colored sclerotia (OS) on agar media was obtained from an orange-colored apothecium of an uncultured soil fungus. Whether or not the OS B. cinerea occurs on plants and how they differ from the BS isolates in melanogensis and ecological fitness remained unknown. This study, for the first time, confirmed the presence of the OS B. cinerea in strawberry and tomato plants that were surveyed in Hubei Province of China. Only five OS isolates were obtained from a total of 2,031 isolates surveyed from the two crops. The OS isolate XN-1 was compared and contrasted with the BS isolate B05.10 in sclerotial melanogenesis and ecological fitness. Sclerotial melanogenesis was evident in B05.10 but was deficient in XN-1. The OS were more susceptible to the two mycoparasites Trichoderma koningiopsis and Clonostachys rosea than the BS. The percentage of viable sclerotia after the mycoparasitism study was significantly (P < 0.01) lower in OS (21%) than in BS (48%). This study also reaffirmed the importance of melanization for survival of B. cinerea sclerotia.
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Harvey, Stephanie G., Heather N. Hannahan, and Carl E. Sams. "Indian Mustard and Allyl Isothiocyanate Inhibit Sclerotium rolfsii." Journal of the American Society for Horticultural Science 127, no. 1 (January 2002): 27–31. http://dx.doi.org/10.21273/jashs.127.1.27.
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Allyl isothiocyanate (AITC) is the predominant isothiocyanate produced by damaged tissues of Indian mustard (Brassica juncea (L) Czerniak). This study investigated Indian mustard and AITC mediated suppression of mycelial growth and sclerotial germination of Sclerotium rolfsii Saccardo, a common soilborne pathogen. Indian mustard (IM) treatments of 0, 0.1, 0.2, 0.6, 1.0, 2.0, 4.1, 5.1, 10.2, 20.4, 40.8, 81.6, and 163.3 g·L-1 (weight of reconstituted mustard per liter of air) were evaluated for suppression of mycelial growth. Treatment effect was evaluated by measuring the radial growth of mycelia. Sclerotia were placed in culture tubes containing 18 g autoclaved soil and covered with an additional 5 g soil. AITC at concentrations of 0, 4.0, 16.0, 64.0, 256.0, 1024.0, or 4096.0 μmol·L-1 was injected into the tubes. Treated sclerotia were removed from tubes and plated on potato dextrose agar to determine viability. Mycelial growth was inhibited with IM treatments (P < 0.01). Inhibiting concentrations (IC) of IM for mycelial growth inhibition of 50% and 90% were 0.7 and 1.0 g·L-1, respectively, with death resulting with >2 g·L-1. Inhibition attributable to AITC alone was lower than that achieved by IM producing equivalent amounts of AITC. Germination of sclerotia was negatively correlated with AITC concentration (r = 0.96; P < 0.01). The IC50 and IC90, of AITC were 249.0 and 528.8 μmol·L-1, respectively, at 42 hours. The lethal concentration for sclerotia was not reached; only suppression occurred at the highest treatment concentrations. Sclerotium rolfsii mycelia were sensitive to the IM volatiles and were suppressed at low concentrations. Sclerotia were more resistant than the mycelia and required higher concentrations of AITC to suppress germination.
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Davis, R. M., J. J. Hao, M. K. Romberg, J. J. Nunez, and R. F. Smith. "Efficacy of Germination Stimulants of Sclerotia of Sclerotium cepivorum for Management of White Rot of Garlic." Plant Disease 91, no. 2 (February 2007): 204–8. http://dx.doi.org/10.1094/pdis-91-2-0204.
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The ability of soil-applied garlic powder and diallyl disulfide to stimulate germination of sclerotia of Sclerotium cepivorum, the cause of white rot of onion and garlic, was evaluated in four field trials. Because sclerotia germinate in response to exudation of specific volatile sulfides and thiols from allium roots, sulfides applied to the ground in the absence of an allium crop cause death of the sclerotia after they germinate and exhaust nutrient reserves. In this study, garlic powder and a synthetic garlic oil, diallyl disulfide, were incorporated into the soil in commercial fields naturally infested with S. cepivorum. Methyl bromide was included as a chemical control. Within 3 months after treatment, over 90% of the sclerotia died in the plots treated with the germinationstimulants, which was similar to the reduction of viable sclerotia achieved with an application of methyl bromide. The degree of sclerotial mortality in plots treated with garlic powder at 112 kg/ha or more was almost equal to that achieved by diallyl disulfide at 0.5 ml/m2 or methyl bromide at 448 kg/ha. Despite the efficacy of the stimulants and methyl bromide to reduce populations of sclerotia, the pathogen caused substantial root rot and yield losses in subsequent garlic crops planted about a year after soil treatment. However, germination stimulants have utility because the reduction of the vast majority of sclerotia in a field reduces the risk of spread of the pathogen to neighboring fields.
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Amaike, Saori, and Nancy P. Keller. "Distinct Roles for VeA and LaeA in Development and Pathogenesis of Aspergillus flavus." Eukaryotic Cell 8, no. 7 (May 1, 2009): 1051–60. http://dx.doi.org/10.1128/ec.00088-09.
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ABSTRACT Aspergillus flavus, a mycotoxigenic filamentous fungus, colonizes several important agricultural crops, such as maize and peanuts. Two proteins, VeA and LaeA, known to form a nuclear complex in Aspergillus nidulans have been found to positively regulate developmental processes in several Aspergillus species. Here, an examination of near-isogenic A. flavus mutants differing in copy number of veA and laeA alleles (0, 1, or at least 2 each) revealed critical roles for VeA and LaeA in A. flavus development and seed colonization. In contrast to the wild type, both null mutants were unable to metabolize host cell lipid reserves and were inhibited by oleic acid in growth assays. The copy number of LaeA but not VeA appeared critical for a density-dependent sclerotial-to-conidial shift, since the multicopy laeA (MClaeA) strain produced relatively constant sclerotial numbers with increasing population size rather than showing the decrease in sclerotia seen in both the wild-type and MCveA strains. The MCveA-laeA strain yielded an intermediate phenotype. This study revealed unique roles of VeA and LaeA in seed pathogenesis and fungal biology, distinct from their cooperative regulatory functions in aflatoxin and sclerotial development.
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Li, Moyi, Xiaofei Liang, and Jeffrey A. Rollins. "Sclerotinia sclerotiorum γ-Glutamyl Transpeptidase (Ss-Ggt1) Is Required for Regulating Glutathione Accumulation and Development of Sclerotia and Compound Appressoria." Molecular Plant-Microbe Interactions® 25, no. 3 (March 2012): 412–20. http://dx.doi.org/10.1094/mpmi-06-11-0159.
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Transcripts encoding Sclerotinia sclerotiorum γ-glutamyl transpeptidase (Ss-Ggt1) were found to accumulate specifically during sclerotium, apothecium, and compound appressorium development in S. sclerotiorum. To determine the requirement of this protein in these developmental processes, gene deletion mutants of Ss-ggt1 were generated and five independent homokaryotic ΔSs-ggt1 mutants were characterized. All deletion mutants overproduced sclerotial initials that were arrested in further development or eventually produced sclerotia with aberrant rind layers. During incubation for carpogenic germination, these sclerotia decayed and failed to produce apothecia. Total glutathione accumulation was approximately 10-fold higher and H2O2 hyperaccumulated in ΔSs-ggt1 sclerotia compared with the wild type. Production of compound appressoria was also negatively affected. On host plants, these mutants exhibited a defect in infection efficiency and a delay in initial symptom development unless the host tissue was wounded prior to inoculation. These results suggest that Ss-Ggt1 is the primary enzyme involved in glutathione recycling during these key developmental stages of the S. sclerotiorum life cycle but Ss-Ggt1 is not required for host colonization and symptom development. The accumulation of oxidized glutathione is hypothesized to negatively impact these developmental processes by disrupting the dynamic redox environment associated with multicellular development.
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Somerville, Prudence A. "Factors Affecting Sclerotial Germination of Sclerotium cepivorum, Secondary Sclerotia Formation, and Germination Stimulants to Reduce Inoculum Density." Plant Disease 71, no. 3 (1987): 229. http://dx.doi.org/10.1094/pd-71-0229.
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Rather, Roaf Ahmad, Farooq Ahmad Ahanger, Shafat Ahmad Ahanger, Umer Basu, M. Altaf Wani, Zahida Rashid, Parvaze Ahmad Sofi, et al. "Morpho-Cultural and Pathogenic Variability of Sclerotinia sclerotiorum Causing White Mold of Common Beans in Temperate Climate." Journal of Fungi 8, no. 7 (July 21, 2022): 755. http://dx.doi.org/10.3390/jof8070755.
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The present systematic research on cultural, morphological, and pathogenic variability was carried out on eighty isolates of Sclerotinia sclerotiorum collected from major common bean production belts of North Kashmir. The isolates were found to vary in both cultural and morphological characteristics such as colony color and type, colony diameter, number of days for sclerotia initiation, sclerotia number per plate, sclerotial weight, and size. The colony color ranged between white and off-white with the majority. The colony was of three types, in majority smooth, some fluffy, and a few fluffy-at-center-only. Colony diameter ranged between 15.33 mm and 29 mm after 24 h of incubation. The isolates took 4 to 7 days for initiation of sclerotia and varied in size, weight, and number per plate ranging between 14 and 51.3. The sclerotial arrangement pattern on plates was peripheral, sub peripheral, peripheral, and subperipheral, arranged at the rim and scattered. A total of 22 Mycelial compatibility groups (MCGs) were formed with seven groups constituted by a single isolate. The isolates within MCGs were mostly at par with each other. The six isolates representing six MCGs showed variability in pathogenicity with isolate G04 as the most and B01 as the least virulent. The colony diameter and disease scores were positively correlated. Sclerotia were observed to germinate both myceliogenically and carpogenically under natural temperate conditions of Kashmir. Germplasm screening revealed a single resistant line and eleven partially resistant lines against most virulent isolates.
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Xu, Yan, Kevin Ao, Lei Tian, Yilan Qiu, Xingchuan Huang, Xueru Liu, Ryan Hoy, et al. "A Forward Genetic Screen in Sclerotinia sclerotiorum Revealed the Transcriptional Regulation of Its Sclerotial Melanization Pathway." Molecular Plant-Microbe Interactions® 35, no. 3 (March 2022): 244–56. http://dx.doi.org/10.1094/mpmi-10-21-0254-r.
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Most plant fungal pathogens that cause worldwide crop losses are understudied, due to various technical challenges. With the increasing availability of sequenced whole genomes of these non-model fungi, effective genetic analysis methods are highly desirable. Here, we describe a newly developed pipeline, which combines forward genetic screening with high-throughput next-generation sequencing to enable quick gene discovery. We applied this pipeline in the notorious soilborne phytopathogen Sclerotinia sclerotiorum and identified 32 mutants with various developmental and growth deficiencies. Detailed molecular studies of three melanization-deficient mutants provide a proof of concept for the effectiveness of our method. A master transcription factor was found to regulate melanization of sclerotia through the DHN (1,8-dihydroxynaphthalene) melanin biosynthesis pathway. In addition, these mutants revealed that sclerotial melanization is important for sclerotia survival under abiotic stresses, sclerotial surface structure, and sexual reproduction. Foreseeably, this pipeline can be applied to facilitate efficient in-depth studies of other non-model fungal species in the future. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .