Dissertations / Theses on the topic 'Systemic acquired resistance'
To see the other types of publications on this topic, follow the link: Systemic acquired resistance.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Systemic acquired resistance.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Qin, Xiaohui. "Papaya systemic acquired resistance." Thesis, University of Hawaii at Manoa, 2003. http://hdl.handle.net/10125/6872.
Full textAbstract:
Challenge by a pathogen induces systemic acquired resistance (SAR) in plants, a state marked by the elevated expression of pathogenesis related (PR) genes and enhanced resistance to a broad spectrum of pathogens. SAR requires the endogenous accumulation of salicylic acid (SA), and can be induced by exogenous application of SA or related molecules such as benzo(1,2,3) thiadiazole-7-carbothioic acid S-methyl ester (BTH). All tested plants have a SAR response, but some important aspects of SAR differ between species. In this work, four (partial) PR-1 cDNAs were cloned from papaya. One of these, PR-1d, was shown to be induced by BTH. This data, together with previous data showing the induction of SAR related enzymes and enhanced tolerance to a pathogen in response to BTH, demonstrates that papaya has a SAR response and it is induced by BTH. With this knowledge, global profiling of papaya genes induced by BTH was carried out by suppression subtractive hybridization. 25 unique expressed sequence tags (ESTs) induced by BTH were identified, including homologs of numerous genes known to be defense related, and some genes previously unknown to have defense functions. A papaya homolog of NPRl, shown to be required for SAR signal transduction in Arabidopsis, was isolated and found to contain all three structural domains required for activity in Arabidopsis. This data, together with the profile of BTH induced genes, and induction kinetics for some of these genes, shows that papaya SAR is similar in many important aspects to SAR in the model system Arabidopsis. Additionally, tobacco plants over-expressing Arabidopsis NPRI were produced and found to produce elevated (compared to wild-type) levels of PR-la mRNA in response to SA treatment. This demonstrates that even in a heterologous system, over-expression of NPRl may confer an enhanced SAR response.xvi, 116 leaves
2
Darby, Judith. "Systemic acquired resistance to Phytophthora infestans in potatoes and tomatoes." Thesis, University of Hull, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321051.
Full text
3
Bokshi, A. I. "POSTHARVEST DISEASE CONTROL OF MELONS USING SYSTEMIC ACQUIRED RESISTANCE AND OTHER." Thesis, The University of Sydney, 2008. http://hdl.handle.net/2123/3938.
Full textAbstract:
The goal of this research was to test commercially viable alternative methods to fungicides for controlling storage diseases of melons that are safe for human health and the environment. Initially, experiments were conducted on melons to develop a protocol for optimum conditions of disease development during storage for different pathogens and for different stages of fruit maturity. For all pathogens tested, the study found that humidity greater than 90% and temperatures above 20° C support infection and rapid growth of disease. Differences in the rate of infection and extent of disease development after the inoculation of different storage pathogens was observed between rockmelon and honeydew melons, indicating differences in host pathogen interactions. Among the tested pathogens, Alternaria spp. was the least aggressive in infection and disease severity, growing considerably slower than Fusarium acuminatum which was moderately aggressive and Rhizopus spp. which was very aggressive, in comparison. Green half-slip melons showed greater resistance to pathogen attack than green full-slip fruit, while yellow full-slip melons were highly susceptible to pathogen attack. Therefore, the laboratory experiments for postharvest treatments of rockmelons were performed using green full-slip fruit challenged with F. acuminatum. Evaluation of physical and safe chemical methods of postharvest treatment to control postharvest diseases of melons showed that none of the treatments alone was as effective as the commercially available fungicide. Hot water solutions of safe compounds considerably increase their efficacy against postharvest rots, however, symptoms of phytotoxicity on the rind after dipping made their use unacceptable. Iodine was the only safe chemical tested which did not cause any phytotoxicity on melons. When combined with hot water, iodine showed the best control of storage rots and was as good as the fungicides carbendazim or guazatine. Hot water iodine dipping of fruit also delayed ripening and fruit were firmer during storage for a longer period of time. Systemic acquired resistance (SAR) was evaluated as a method of controlling powdery mildew in glasshouse grown rockmelon seedlings by treating with the activators 2,6-dichloroisonicotinic acid (INA) or benzothiadiazole (BTH) or water. Increased resistance due to application of INA or BTH, was observed by the reduction of powdery mildew on pre-inoculated detached leaves and also on intact leaves from natural infections. Heightened resistance due to spraying with elicitors of SAR, was further evident by the increased activities of the pathogenesis related proteins (PR proteins), peroxidase and accumulation of phenolics or antifungal compounds during and after challenge inoculation. Field grown rockmelons were treated with INA or BTH or BABA (β-aminobutyric acid) or water at various stages of plant growth and evaluated for increased resistance against pre and postharvest diseases. Both powdery mildew and downy mildew were significantly less on the SAR elicitor treated plants. Preharvest treatment with SAR elicitors also reduced storage diseases of the harvested rockmelon fruit. The reduction in postharvest disease was similar whether plants were treated once, three weeks before harvest, or given four sprays during the growing season beginning at anthesis. A further postharvest dip with 500 ppm of guazatine gave substantial reduction of storage rots of melons. Enhanced activities of chitinase and peroxidase, two major PR-proteins, compared to the control, indicated induction of defence had occurred in the foliage and fruit as a result of SAR. Over the course of four field and one glasshouse experiments slight phytotoxicity was observed in plants frequently sprayed with INA or BTH, but no phytotoxicity was seen after a single spray during the late stages of fruit development. The combination of SAR elicitor treatment and use of a safe postharvest dip provided substantial control of storage rots of rockmelons. The best treatment for control of storage rots involved application of BTH (50 ppm) two weeks before harvest, combined with a hot iodine dip (55° C) of fruit, achieving equivalent or better disease control than use of guazatine fungicide dip.
4
Bokshi, A. I. "POSTHARVEST DISEASE CONTROL OF MELONS USING SYSTEMIC ACQUIRED RESISTANCE AND OTHER." University of Sydney, 2008. http://hdl.handle.net/2123/3938.
Full textAbstract:
Doctor of Philosophy (PhD)The goal of this research was to test commercially viable alternative methods to fungicides for controlling storage diseases of melons that are safe for human health and the environment. Initially, experiments were conducted on melons to develop a protocol for optimum conditions of disease development during storage for different pathogens and for different stages of fruit maturity. For all pathogens tested, the study found that humidity greater than 90% and temperatures above 20° C support infection and rapid growth of disease. Differences in the rate of infection and extent of disease development after the inoculation of different storage pathogens was observed between rockmelon and honeydew melons, indicating differences in host pathogen interactions. Among the tested pathogens, Alternaria spp. was the least aggressive in infection and disease severity, growing considerably slower than Fusarium acuminatum which was moderately aggressive and Rhizopus spp. which was very aggressive, in comparison. Green half-slip melons showed greater resistance to pathogen attack than green full-slip fruit, while yellow full-slip melons were highly susceptible to pathogen attack. Therefore, the laboratory experiments for postharvest treatments of rockmelons were performed using green full-slip fruit challenged with F. acuminatum. Evaluation of physical and safe chemical methods of postharvest treatment to control postharvest diseases of melons showed that none of the treatments alone was as effective as the commercially available fungicide. Hot water solutions of safe compounds considerably increase their efficacy against postharvest rots, however, symptoms of phytotoxicity on the rind after dipping made their use unacceptable. Iodine was the only safe chemical tested which did not cause any phytotoxicity on melons. When combined with hot water, iodine showed the best control of storage rots and was as good as the fungicides carbendazim or guazatine. Hot water iodine dipping of fruit also delayed ripening and fruit were firmer during storage for a longer period of time. Systemic acquired resistance (SAR) was evaluated as a method of controlling powdery mildew in glasshouse grown rockmelon seedlings by treating with the activators 2,6-dichloroisonicotinic acid (INA) or benzothiadiazole (BTH) or water. Increased resistance due to application of INA or BTH, was observed by the reduction of powdery mildew on pre-inoculated detached leaves and also on intact leaves from natural infections. Heightened resistance due to spraying with elicitors of SAR, was further evident by the increased activities of the pathogenesis related proteins (PR proteins), peroxidase and accumulation of phenolics or antifungal compounds during and after challenge inoculation. Field grown rockmelons were treated with INA or BTH or BABA (β-aminobutyric acid) or water at various stages of plant growth and evaluated for increased resistance against pre and postharvest diseases. Both powdery mildew and downy mildew were significantly less on the SAR elicitor treated plants. Preharvest treatment with SAR elicitors also reduced storage diseases of the harvested rockmelon fruit. The reduction in postharvest disease was similar whether plants were treated once, three weeks before harvest, or given four sprays during the growing season beginning at anthesis. A further postharvest dip with 500 ppm of guazatine gave substantial reduction of storage rots of melons. Enhanced activities of chitinase and peroxidase, two major PR-proteins, compared to the control, indicated induction of defence had occurred in the foliage and fruit as a result of SAR. Over the course of four field and one glasshouse experiments slight phytotoxicity was observed in plants frequently sprayed with INA or BTH, but no phytotoxicity was seen after a single spray during the late stages of fruit development. The combination of SAR elicitor treatment and use of a safe postharvest dip provided substantial control of storage rots of rockmelons. The best treatment for control of storage rots involved application of BTH (50 ppm) two weeks before harvest, combined with a hot iodine dip (55° C) of fruit, achieving equivalent or better disease control than use of guazatine fungicide dip.
5
Nair, Aswin [Verfasser]. "Salicylic Acid (SA)-independent processes in Systemic Acquired Resistance (SAR) / Aswin Nair." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2021. http://d-nb.info/1230138110/34.
Full text
6
Murray, Shane Louise. "Identification and characterisation of Arabidopsis systemic acquired resistance mutants isolated by luciferase imaging." Thesis, University of Edinburgh, 2000. http://hdl.handle.net/1842/11207.
Full textAbstract:
Plants have evolved a complex series of integrated defence mechanisms against pathogens. Following recognition of a pathogen avirulence (avr) gene product by the corresponding plant resistance (R) gene product, a complex signalling network is initiated. Local inducible defences are activated and a long-distance signal is released, leading to the establishment of systemic acquired resistance (SAR) to a wide range of pathogens. SAR is marked by the accumulation of pathogenesis-related (PR) proteins. Salicylic acid (SA) is a key signalling molecule in SAR, inducing PR gene expression both locally and systemically. In order to study further the molecular basis of SAR, we have developed a method of identifying novel SAR mutants by luciferase imaging. Transgenic Arabidopsis thaliana plants expressing a PR1a-luciferase reporter gene were generated and homozygous seed was chemically mutagenised. Mutants with perturbations in PR1 gene expression were identified and could be divided into various classes. A novel mutant expressing PR1 constitutively was selected for further study. cir1 (constitutively induced resistance 1) expressed both SA-dependent and SA-independent defence genes constitutively, accumulated SA to high levels and produced an increased amount of ethylene. In addition, cir1 exhibited resistance to the virulent bacterial pathogen Pseudomonas syringae pv tomato DC3000 and the virulent oomycete pathogen Peronospora parisitica Noco2. Genetic analyses indicated that cir1 is recessive and defines a mutation in a single gene, cir1 mapped to the lower arm of chromosome 4. Double mutants were produced between cirl and SA-, JA- and ethylene-insensitive mutants. Analysis of these plants showed that SA, JA and ethylene were required for constitutive defence gene expression and disease resistance in cir1. Thus, the results obtained indicate that CIR1 acts as a negative regulator in the disease resistance signal transduction network, most likely functioning upstream of the branchpoint between the SA-dependent and SA-independent pathways.
7
Bokshi, Anowarul Islam. "Postharvest disease control of melons using systemic acquired resistance and other safe methods." Connect to full text, 2008. http://ses.library.usyd.edu.au/handle/2123/3938.
Full textAbstract:
Thesis (Ph. D.)--University of Sydney, 2008.Includes graphs and tables. Includes list of publications co-authored with others. Title from title screen (viewed November 28, 2008. Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Faculty of Agriculture, Food and Natural Resources. Includes bibliographical references. Also available in print form.
8
Tripathi, Diwaker. "Role of SABP2 in Systemic Acquired Resistance Induced by Acibenzolar-S-Methyl in Plants." Digital Commons @ East Tennessee State University, 2010. https://dc.etsu.edu/etd/1720.
Full textAbstract:
Plants have evolved an efficient mechanism to defend themselves against pathogens. Many biotic and abiotic agents have been shown to induce defense mechanism in plants. Acibenzolar-S-Methyl (ASM) is a commercially available chemical inducer of local and systemic resistance (SAR) response in plants. ASM functioning at molecular level is mostly unclear. This research was designed to investigate the mechanism of ASM action in plants. It was hypothesized that SABP2, a plant protein, plays an important role in ASM-mediated defense signaling. Biochemical studies were performed to test the interaction between SABP2 and ASM. Transgenic SABP2-silenced tobacco plants were used to determine the role of SABP2 in SAR induced by ASM. The expression of PR-1 proteins was used as a marker for SAR induction. Results showed that SABP2 converts ASM into acibenzolar that induces the expression of PR-1 proteins and develops the SAR response in ASM-treated plants.
9
Krothapalli, Kartikeya. "Association of plastid lipid metabolism with the activation of systemic acquired resistance in Arabidopsis thaliana." Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/1058.
Full text
10
Gaikwad, Trupti. "Investigating the initial signalling mechanisms underpinning gene-for-gene mediated Systemic Acquired Resistance in Arabidopsis thaliana." Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/30057.
Full textAbstract:
Plants deploy two key active defensive strategies to combat microbial pathogens; (i) Recognition of Pathogen-Associated Molecular Patterns (PAMPs) by extracellular surface receptors leading to the activation of PAMP-Triggered Immunity (PTI); (ii) Recognition of pathogen effector activity, usually intracellularly, by host Resistance (R) proteins leading to Effector-Triggered Immunity (ETI). ETI is characterised by a rapid localised Hypersensitive Response (HR). HR induces Systemic Acquired Resistance (SAR) through the production of an inducible immune signal(s), leading to broad spectrum systemic resistance. I investigated the earliest events associated with SAR signalling using plant electrophysiology, SAR mutants and a unique promoter-luciferase fusion that captures early systemic transcriptional events associated with ETI. We describe the transcriptional dynamics of A70 (At5g56980), a gene of unknown function (Truman et al. 2007), in local and systemic tissue following challenge with different elicitors and virulent or avirulent pathogen challenges. We provide evidence that A70 responds to a jasmonate (JA) related signal that is rapidly generated following ETI recognition. We further evaluate A70::LUC reporter activity in response to JA stimulus and correlate activity with histological expression of a JA repressor reporter (JAZ10::GUS) and A70::GFP reporter in systemically responding leaves following avirulent pathogen challenges. Finally, we examine changes in electrophysiological signals following ETI in local and systemic leaves. Focussing on events underpinning initiation, propagation and perception of SAR-inducing signals within the first 6-8 h of pathogen challenge we provide new insight into the integrated signalling mechanisms, dynamics and connectivity underpinning systemic immune responses. We conclude that there are multicomponent signals that link ETI induced transcriptional and electrical signals, with a COI1 receptor dependent propagative transcriptional wave the leads to rapid temporal spatial activation of jasmonate responsive genes in systemic responding leaves.
11
Ajami-Rashidi, Ziba [Verfasser], Jürgen [Gutachter] Zeier, and Laura [Gutachter] Rose. "Environmental influences and genetic regulation on systemic acquired resistance / Ziba Ajamirashidi ; Gutachter: Jürgen Zeier, Laura Rose." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2020. http://d-nb.info/1213971489/34.
Full text
12
Ajamirashidi, Ziba [Verfasser], Jürgen [Gutachter] Zeier, and Laura [Gutachter] Rose. "Environmental influences and genetic regulation on systemic acquired resistance / Ziba Ajamirashidi ; Gutachter: Jürgen Zeier, Laura Rose." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2020. http://d-nb.info/1213971489/34.
Full text
13
Stolte, Rhett L. "THE INFLUENCE OF SOIL-APPLIED HERBICIDE AND PATHOGEN INTERACTION ON UPREGULATION OF SYSTEMIC ACQUIRED RESISTANCE IN SOYBEAN." OpenSIUC, 2019. https://opensiuc.lib.siu.edu/theses/2533.
Full textAbstract:
Exposure of crop plants to stress or injury, such as soybean injury by PPO-inhibitor herbicide, may stimulate the upregulation of Systemic Acquired Resistance (SAR) and reduce plant susceptibility to other stressors, such as disease-causing pathogens. Field and laboratory studies were initiated to evaluate the upregulation of SAR, examining the effects of PPO-inhibiting herbicide treatment on Sudden Death Syndrome incidence and severity in soybean and the relationship of disease incidence and severity related to stand count and yield with various population densities. A two-year field study was established in Shawneetown, IL to evaluate grain yield and disease potential of soybean cultivars which are either sensitive or tolerant to protoporphyrinogen oxidase (PPO)-inhibitor herbicides, with seed either treated with insecticide, thiamethoxam and fungicides, fludioxonil and mefanoxam (Upshot) and biological fungicide Bacillus amyloliquefaciens strain D747 (Avonni) (biological fungicide) or non-treated. The seeds were planted at six different seeding rates: 197,684; 247,105; 296,526; 345,947; 395,368; 444,789; with the controls planted at a density of 345,947 seeds ha-1 in a 2x2x7 factorial study design. Field experiments were planted on April 25, 2016 and May 6, 2017 in 76 cm, 4-row plots measuring 3m by 7m, and herbicide was applied to treated plots over the center 2 rows. Data collection included crop injury at 14, 28 and 56 days after treatment (DAT), stand count at 14 and 28 (DAT), plant height and node count at end-of-season (EOS), and disease incidence and severity ratings beginning at the onset of symptomology. Yield data was collected from the center two treated rows. All plots, except the non-treated controls, received an application of sulfentrazone + cloransulam-methyl (316 g ai ha-1). In 2016 the greatest crop injury, categorized by stunting, at 14 DAT occurred in the PPO-tolerant seed variety without a fungicide and insecticide seed treatment at 4.2% planted at 444,789 seeds/ha. At 28 DAT with means pooled over seed treatment and seed variety, we observed the 197,684 seeds/ha plots having greatest crop injury at 5.25%, and lastly at 56 DAT, the 197,684 and 247,105 seeds/ha plots containing untreated, PPO-sensitive seed were the most injured at 12% crop injury. In 2017, 14 DAT was excluded from the analysis, as there was no injury at the time of rating. At 28 DAT, the PPO-sensitive seed variety, pooled over seed treatment, at 197,684 seeds/ha resulted in greater crop injury at 8.6%, similar to 2016. At 56 DAT, similar results were observed as in 2016, at 12% crop injury in the PPO-sensitive seed variety without a seed treatment planted at 197,684 seeds/ha. There were differences in stand count by seeding rate at 14 and 28 DAT, but no interactive effects between the factors in 2016; seed treatment and seed variety were not significant. However, in 2017, there were differences in stand count by seed variety and seed treatment at 14 and 28 DAT, but again, no interactive effects between factors. Relationships between stand count and seeding rate indicated a threshold at which the environment cannot sustain higher planting densities. Environmental conditions were more favorable for crop growth in 2016 than 2017. Rainfall 10 days following planting was recorded at 67 mm and 290 mm in 2016 and 2017, respectively. Soybean node counts in 2016 were greater in the PPO-tolerant variety were seed was treated with a fungicide and insecticide seed treatment. In 2017, node counts were not influenced by seed treatment or seed variety; however, the greatest number of nodes were in the 444,789 seeds/ha planting population. Disease was more prominent in the high-density plots than in the low-density plots, as would be expected because of the effects of competitive stress on plant susceptibility to pathogens as well as more plants to be infected by the pathogen. Sudden Death Syndrome disease incidence (scale of 0 to 100%) in 2016 ranged from 1.2 to 25.5 across rating dates, while severity (scale of 0 to 9 based on leaf symptomology) ranged from 0.3 to 2.2 across rating dates. In 2017 disease incidence ranged from 0 to 25.0 across all rating dates, and disease severity ranged from 0 to 1.6 across all rating dates. Yield in 2016 ranged from 3,449.8 kg/ha to 4,060.3 kg/ha with the highest yield in the PPO-tolerant variety and the lowest in the -sensitive variety. However, in 2017, yield was lowest in the 197,684 plants/ha treatments at 1,509.1 kg/ha and highest in the 444,789 plants/ha treatments at 4,053.9 kg/ha. Significant varietal and seed treatment differences were also noted in 2017.
14
Conn, Vanessa Michelle, and vanessa conn@acpfg com au. "Molecular Interactions of Endophytic Actinobacteria in Wheat and Arabidopsis." Flinders University. School of Medicine, 2006. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20060320.171412.
Full textAbstract:
Wheat is the most economically important crop forming one quarter of Australian farm production. The wheat industry is severely affected by diseases, with fungal pathogens causing the most important economic losses in Australia. The application of fungicides and chemicals can control crop diseases to a certain extent, however, it is expensive and public concern for the environment has led to alternative methods of disease control to be sought, including the use of microorganisms as biological control agents. Microorganisms are abundant in the soil adjacent to plant roots (rhizosphere) and within healthy plant tissue (endophytic) and a proportion possess plant growth promotion and disease resistance properties.
Actinobacteria are gram-positive, filamentous bacteria capable of secondary metabolite production such as antibiotics and antifungal compounds. A number of the biologically active endophytes belonging to the Actinobacteria phylum were isolated in our laboratory. A number of these isolates were capable of suppressing the wheat fungal pathogens Rhizoctonia solani, Pythium sp. and Gaeumannomyces graminis var. tritici, both in vitro and in planta indicating the potential for the actinobacteria to be used as biocontrol agents. The aim of this research was to investigate the molecular mechanisms underlying this plant-microbe interaction.
The indigenous microbial populations present in the rhizosphere and endophytic environment are critical to plant health and disruptions of these populations are detrimental. The culture-independent technique Terminal Restriction Fragment Length Polymorphism (T-RFLP) was used to characterise the endophytic actinobacteria population of wheat roots under different conditions. Soils which support a higher number of indigenous microorganisms result in wheat roots with higher endophytic actinobacterial diversity and level of colonisation. Sequencing of 16S rRNA gene clones, obtained using the same actinobacteria-biased PCR primers that were used in the T-RFLP analysis, confirmed the presence of the actinobacterial diversity, and identified a number of Mycobacterium and Streptomyces species. It was found that the endophytic actinobacterial population of the wheat plants contained a higher diversity of endophytic actinobacteria than reported previously, and that this diversity varied significantly among different field soils.
The endophytic actinobacteria have previously been shown to protect wheat from disease and enhance growth when coated onto the seed before sowing. As the endophytes isolated were recognised as potential biocontrol agents, the impact on the indigenous endophytic microbial population was investigated. Utilising the T-RFLP technique it was established that the use of a commercial microbial inoculant, containing a large number of soil bacterial and fungal strains applied to the soil, disrupts the indigenous endophyte population present in the wheat roots. The hypothesis is that non-indigenous microbes proliferate and dominate in the soil preventing a number of endophytic-competent actinobacterial genera from access to the seed and ultimately endophytic colonisation of the wheat roots. This dramatically reduces diversity of endophytes and level of colonisation. In contrast the use of a single endophytic actinobacteria endophyte inoculant results in a 3-fold increase in colonisation by the added inoculant, but does not significantly affect this indigenous population.
Colonisation of healthy plant tissues with fungal endophytes has been shown to improve the competitive fitness with enhanced tolerance to abiotic and biotic stress and improved resistance to pathogens and herbivores. In this study the fungal endophyte population of wheat plants grown in four different soils was analysed using partial sequencing of 18S rRNA gene sequences. Sequence anlaysis of clones revealed a diverse range of fungal endophytes. In this diverse range of fungal endophytes a number sequences were highly similar to those of previously known fungal phytopathogens. A number of sequences detected were similar to fungal species previously identified in soil or plant material but not as endophytes. The remaining sequences were similar to fungal species without a known relationship with plants.
Plants have developed an inducible mechanism of defence against pathogens. In addition to local responses plants have developed a mechanism to protect uninfected tissue through a signal that spreads systemically inducing changes in gene expression. In the model plant Arabidopsis thaliana activation of the Systemic Acquired Resistance (SAR) pathway and the Jasmonate (JA)/Ethylene (ET) pathway is characterised by the production of pathogenesis-related (PR) and antimicrobial proteins resulting in systemic pathogen resistance. Endophytic actinobacteria, isolated from healthy wheat roots in our laboratory, have been shown to enhance disease resistance to multiple pathogens in wheat when coated onto the seed before sowing. Real Time RT-PCR was used to determine if key genes in the SAR and JA/ET pathways were induced in response to inoculation with endophytic actinobacteria.
Inoculation of wild-type Arabidopsis thaliana with selected strains of endophytic actinobacteria was able to �prime� the defence pathways by inducing low level expression of SAR and JA/ET genes. Upon pathogen infection the defence-genes are strongly up-regulated and the endophyte coated plants had significantly higher expression of these genes compared to un-inoculated plants. Resistance to the bacterial pathogen Erwinia carotovora subsp. carotovora was mediated by the JA/ET pathway whereas the fungal pathogen Fusarium oxysporum triggered primarily the SAR pathway.
Further analysis of the endophytic actinobacteria-mediated resistance was performed using the Streptomyces sp. EN27 and Arabidopsis defence-compromised mutants. It was found that resistance to E. carotovora subsp. carotovora mediated by Streptomyces sp. EN27 occurred via a NPR1-independent pathway and required salicylic acid whereas the jasmonic acid and ethylene signalling molecules were not essential. In contrast resistance to F. oxysporum mediated by Streptomyces sp. EN27 occurred via a NPR1-dependent pathway but also required salicylic acid and was JA- and ET-independent.
This research demonstrated that inoculating wheat with endophytic actinobacteria does not disrupt the indigenous endophytic population and may be inducing systemic resistance by activating defence pathways which lead to the expression of antimicrobial genes and resistance to a broad range of pathogens.
15
Griffitts, Amanda Aline. "Characterization of Host Plant Defense Responses to Parasitization by Orobanche aegyptiaca." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/42763.
Full textAbstract:
Orobanche (spp.) are parasitic plants that attack the roots of many important crops. O. aegyptiaca penetrates the host root (aided by digestive enzymes) and forms connections to the host vascular tissue, from which it will withdraw all of its water and nutrient requirements. In order to control this weed, it is important to understand the relationship between the host and the parasite. To investigate how parasitism effects host defense pathways, we are studying the patterns of expression of host genes known to be involved in various aspects of plant defense responses. With respect to local defense responses, two genes of the isoprenoid pathway were studied, one of which is expressed in wounded tissue (hmg1), and another that is induced in response to wounding yet repressed in response to pathogen elicitors (squalene synthase). Genes analyzed that are associated with systemic defense include PR-1, PR-2, and PR-5, all of which are induced in response to pathogen attack as part of the systemic acquired resistance (SAR) response. Plant gene expression was studied using transgenic tomato plants containing hmg1-GUS fusions, and northern hybridization analysis of tobacco and Arabidopsis roots using gene-specific probes. Results indicated that expression of hmg1 is induced, PR-2 and squalene synthase are repressed, and PR-1a, PR-1, and PR-5 are not affected in tissue parasitized by O. aegyptiaca. Together, these results indicate a complex response to the parasite. Whereas hmg1 induction is consistent with O. aegyptiaca inflicting a simple wound-like injury, the repression of squalene synthase is consistent with plant recognition of a pathogen attack. In contrast, the failure of Orobanche to induce SAR- related PR-1 in tobacco and PR-1, PR-2, or PR-5 in Arabidopsis indicates an ability to avoid or perhaps inhibit some defense-related pathways. By comparing the regulation of these defense genes in response to O. aegyptiaca attack, we are able to gain a greater understanding of the host plant response to parasitization and explore potential gene candidates for future engineering strategies to create Orobanche resistant crops.Master of Science
16
Le, Thanh Toan, Van Dien Luong, Thi Thuy Nhien Ngo, and Van Kim Pham. "Induced systemic resistance against rice grassy stunt virus – a promising field for ecological rice production." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-88491.
Full textAbstract:
Most rice protection methods have currently used toxic chemicals to control pathogens and pests, which leads to environmental pollution. Systemic acquired resistance (SAR) taking advantage of natural defence reaction of plants could be proposed as an alternative, ecologically friendly approach for plant protection. Its application into rice production could minimize the chemicals quantity used and could contribute to the decrease of environmental pollution and the development of sustainable agriculture. The research was conducted to select the most effective chemical and suitable method to improve the health of rice plants infected by grassy stunt disease in net-house of Can Tho University. SAR chemicals were used at very low concentrations (in mM). Results showed that the height of rice plants treated with SAR chemicals was higher than that of plants untreated. Besides, the number of diseased plants was reduced and the ratio of firm grain and yield increased when plants were applied by SAR. Among the used substances, oxalic acid provided the best systemic acquired resistance. With oxalic acid, seed soaking was better than seed coating in systemic acquired resistance against rice grassy stunt diseaseHầu hết các phương pháp sản xuất lúa hiện nay đều sử dụng các hóa chất độc hại trong việc phòng trừ bệnh và côn trùng gây hại, nên dẫn đến ô nhiễm môi trường. Kích thích tính kháng lưu dẫn giúp kích hoạt cơ chế tự nhiên kháng bệnh của cây có thể là giải pháp bảo vệ thực vật thay thế an toàn với môi trường. Việc ứng dụng tiến bộ này vào trong sản xuất lúa có thể làm giảm lượng hóa chất sử dụng, đóng góp vào việc giảm thiểu ô nhiễm môi trường và sự phát triển của một nền nông nghiệp bền vững. Nghiên cứu đã được thực hiện tại nhà lưới trường Đại học Cần Thơ để tuyển chọn hóa chất và phương pháp sử dụng hóa chất để tăng cường sức khỏe giúp cây lúa vượt qua bệnh vàng lùn. Hóa chất kích kháng được sử dụng ở một nồng độ rất thấp (đơn vị là mM). Kết quả cho thấy chiều cao cây lúa khi xử lý chất kích kháng tốt hơn so đối chứng không xử lý. Bên cạnh đó, số cây lúa nhiễm bệnh giảm, tỉ lệ hạt chắc và năng suất tăng khi cây lúa được xử lý với chất kích kháng. Trong số các chất kích kháng đã sử dụng, acid oxalic cho hiệu quả vượt trội. Với chất acid oxalic, phương pháp ngâm hạt cho hiệu quả kích kháng tốt hơn phương pháp áo hạt
17
Liu, Changxin. "Involvement of Polyamines in PAMP-triggered Immunity and Systemic Acquired Resistance (SAR). Extragenic Suppressors of Immune Hybrid Incompatibility." Doctoral thesis, Universitat de Barcelona, 2020. http://hdl.handle.net/10803/671759.
Full textAbstract:
The main topic of this Thesis is to investigate the contribution of polyamines to defense in Arabidopsis thaliana and the requirement of callose deposition for full expression of effector-triggered immunity in autoimmune hybrids. Due to its accumulation during pathogen infection, I mainly focused on the polyamine putrescine. The interaction between polyamines, reactive oxygen species (ROS) production and salicylic acid pathway activation is also studied in the context of PAMP-triggered immunity (PTI) (Chapter 1) and systemic acquired resistance (SAR) (Chapter 2). The data support a role for putrescine as a priming agent contributing to resistance against pathogens, which can lead to practical applications in the development of PPP (plant protection products). In Chapter 3, I report the involvement of glucan synthase-like 2 and 10 (GSL2 and GSL10), two of the twelve callose biosynthesis genes, in the temperature-dependent immune hybrid incompatibility between natural accessions of Arabidopsis thaliana from North Europe (Ler) and Central Asia (Kas-2), which constitutes a model for the study of effector-triggered immunity (ETI). This work supports that PTI and ETI are not two separate branches of defense, but support each other through mutual potentiation.
Overall, we provide evidence for the involvement of polyamines in defense signaling and callose biosynthesis in the establishment of ETI.
18
CORSI, BEATRICE. "An alternative to the use of pesticides: chitosan as an elicitor of systemic acquired resistance (SAR) in plants." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2013. http://hdl.handle.net/2108/202033.
Full textAbstract:
Kiwifruit is a commercial crop threatened by attack of its most dangerous pathogen, Pseudomonas syringae pv. actinidiae (PSA). Currently, the European Economic Community has engaged in a policy of replacing chemical pesticides with natural substances. Following the European trend, this study is dealing with the prevention of disease outbreaks by growing plants able to better resist pathogen infection through the use of chitosan, a biodegradable, well-known elicitor of Systemic Acquired Resistance (SAR). The aim of this work was to improve the quality of Actinidia plants by a sustainable approach and reduce costs for the containment of phytopathological disorders. It was a 3-years project. In the first year, in vitro cultures of Actinidia deliciosa (A. Chev) C.F. Liang & A.R. Ferguson were chosen as model system to investigate the mechanisms of interaction between chitosan (elicitor) and the host plant. In order to understand the response to elicitation in planta, some effects of chitosan on the detoxification of reactive oxygen species (by guaiacol peroxidase [G-POD] and ascorbate peroxidase [APX]) and on the metabolism of phenolic compounds (by phenylalanine ammonia lyase [PAL] and polyphenol oxidase [PPO]) were monitored. Effectively, chitosan has been able to increase activity of the selected SAR biochemical markers in multiplication and rooting stages. In the second year, to study chitosan-host plant interaction in the presence of a pathogen, 2 year old plants belonging to two different species (Actinidia chinensis Planch. and A. deliciosa) were artificially inoculated with PSA in greenhouse experiments. The symptoms and SAR’s onset were investigated using morphological and biochemical analyses. Chitosan had the ability to enhance several activities of enzymes involved in detoxification processes (G-POD and APX) and in increasing plant defence barriers (PAL and PPO). Furthermore, plant’s defence responses were studied at molecular level. After a screening of possible SAR markers, Pathogenesis-Related proteins (PR1 and PR5) were chosen. Chitosan’s elicitation effect was determined by qRT-PCR and compared to the action of the most common SAR elicitors, such as salicylic acid, methyl jasmonate and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC). As shown by the changes in PR transcription profiles, chitosan elicited a systemic response, with intensity comparable to other well-known signalling molecules. During the third year the validation of previously obtained results was undertaken. The changes in PR transcription profiles were corroborated in 2 year old plants, confirming that chitosan also elicits a systemic response in kiwifruit plants. In addition, a field trial with a natural presence of the pathogen was carried out and the kiwi plant response was determined by molecular techniques. If field trials will confirm the efficacy of chitosan in improving the behaviour of Actinidia plants under pathogen attack, further evidence will be added to support consideration of chitosan as sustainable and eco-friendly alternative for the reduction of pesticide use. In practice, a controlled induction of SAR with chitosan may be useful to alternate and integrate chemical treatments in a modern management of crop protection based on integrated control programs, including the use of environmentally safe products.
19
Njoroge, Mumbi Agnes. "Strategies for improved disease resistance in micro-propagated bananas." Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/61603/1/Mumbi_Njoroge_Thesis.pdf.
Full textAbstract:
Bananas (Musa sp) are one of the most important food crops in the world and provide a staple food and source of income in many households especially in Africa. Diseases are a major constraint to production with bunchy top, caused by Banana bunchy top virus (BBTV) generally considered the most important virus disease of bananas worldwide. Of the fungal diseases, Fusarium wilt, caused by the Fusarium oxysporum f.sp cubense (Foc), and black Sigatoka, caused by Mycosphaerella fijiensis, are arguably two of the most important and cause significant yield losses. The low fertility of commercially important banana cultivars has hampered efforts to generate disease resistance using conventional breeding. Possible alternative strategies to generate or increase disease resistance are through genetic engineering or by manipulation of the innate plant defence mechanisms, namely systemic acquired resistance (SAR). The first research component of this thesis describes attempts to generate BBTV-resistant banana plants using a genetic modification approach. The second research component of the thesis focused on the identification of a potential marker gene associated with SAR in banana plants and a comparison of the expression levels of the marker gene in response to biotic and abiotic stresses, and chemical inducers.
Previous research at QUT CTCB showed that replication of BBTV DNA components in banana embryogenic cell suspensions (ECS) was abolished following co-bombardment with 1.1mers of mutated BBTV DNA-R. BBTV DNA-R encodes the master replication protein (Rep) and is the only viral protein essential for BBTV replication. In this study, ECS of banana were stably transformed with the same constructs, each containing a different mutation in BBTV DNA-R, namely H41G, Y79F and K187M, to examine the effect on virus replication in stably transformed plants. Cells were also transformed with a construct containing a native BBTV Rep. A total of 16, 16, 11 and five lines of stably transformed banana plants containing the Y79F, H41G, K187M and native Rep constructs, respectively, were generated. Of these, up to nine replicates from Y79F lines, four H41G lines, seven K187M lines and three native Rep lines were inoculated with BBTV by exposure to viruliferous aphids in two separate experiments. At least one replicate from each of the nine Y79F lines developed typical bunchy top symptoms and all tested positive for BBTV using PCR. Of the four H41G lines tested, at least one replicate from three of the lines showed symptoms of bunchy top and tested positive using PCR. However, none of the five replicates of one H41G line (H41G-3) developed symptoms of bunchy top and none of the plants tested positive for BBTV using PCR. Of the seven K187M lines, at least one replicate of all lines except one (K187M-1) developed symptoms of bunchy top and tested positive for BBTV. Importantly, none of the four replicates of line K187M-1 showed symptoms or tested positive for BBTV. At least one replicate from each of the three native Rep lines developed symptoms and tested positive for BBTV. The H41G-3 and K187M-1 lines possibly represent the first transgenic banana plants generated using a mutated Rep strategy.
The second research component of this thesis focused on the identification of SAR-associated genes in banana and their expression levels in response to biotic and abiotic stresses and chemical inducers. The impetus for this research was the observation that tissue-cultured (TC) banana plants were more susceptible to Fusarium wilt disease (and possibly bunchy top disease) than plants grown from field-derived suckers, possibly due to decreased levels of SAR gene expression in the former. In this study, the pathogenesis-related protein 1 (PR-1) gene was identified as a potential marker for SAR gene expression in banana. A quantitative real-time PCR assay was developed and optimised in order to determine the expression of PR-1, with polyubiquitin (Ubi-1) found to be the most suitable reference gene to enable relative quantification. The levels of PR-1 expression were subsequently compared in Lady Finger and Cavendish (cv. Williams) banana plants grown under three different environmental conditions, namely in the field, the glass house and in tissue-culture. PR-1 was shown to be expressed in both cultivars growing under different conditions. While PR-1 expression was highest in the field grown bananas and lowest in the TC bananas in Lady Finger cultivar, this was not the case in the Cavendish cultivar with glass house plants exhibiting the lowest PR-1 expression compared with tissue culture and field grown plants. The important outcomes of this work were the establishment of a qPCR-based assay to monitor PR-1 expression levels in banana and a preliminary assessment of the baseline PR-1 expression levels in two banana cultivars under three different growing conditions.
After establishing the baseline PR-1 expression levels in Cavendish bananas, a study was done to determine whether PR-1 levels could be increased in these plants by exposure to known banana pathogens and non-pathogens, and a known chemical inducer of SAR. Cavendish banana plants were exposed to pathogenic Foc subtropical race 4 (FocSR4) and non-pathogenic Foc race 1 (Foc1), as well as two putative inducers of resistance, Fusarium lycopersici (Fol) and the chemical, acibenzolar-S-methyl (BION®). Tissue culture bananas were acclimatised under either glass house (TCS) or field (TCH) conditions and treatments were carried out in a randomised complete block design. PR-1 expression was determined using qPCR for both TCS and TCH samples for the period 12-72h post-exposure. Treatment of TCH plants using Foc1 and FocSR4 resulted in 120 and 80 times higher PR-1 expression than baseline levels, respectively. For TCS plants treated with Foc1, PR-1 expression was 30 times higher than baseline levels at 12h post-exposure, while TCS plants treated with FocSR4 showed the highest PR-1 expression (20 times higher than baseline levels) at 72h post-exposure. Interestingly, when TCS plants were treated with Fol there was a marked increase of PR-1 expression at 12 h and 48 h following treatment which was 4 and 8 times higher than the levels observed when TCS plants were treated with Foc1 and FocSR4, respectively. In contrast, when TCH plants were treated with Fol only a slight increase in PR-1 expression was observed at 12 h, which eventually returned to baseline levels. Exposure of both TCS and TCH plants to BION® resulted in no effect on PR-1 expression levels at any time-point. The major outcome of the SAR study was that the glass house acclimatised tissue culture bananas exhibited lower PR-1 gene expression compared to field acclimatised tissue culture plants and the identification of Fol as a good candidate for SAR induction in banana plants exhibiting low PR-1 levels.
A number of outcomes that foster understanding of both pathogen-derived and plant innate resistance strategies in order to potentially improve banana resistance to diseases were explored in this study and include identification of potential inducers of systemic acquired resistance and a promising mutated Rep approach for BBTV resistance. The work presented in this thesis is the first report on the generation of potential BBTV resistant bananas using the mutated Rep approach. In addition, this is the first report on the status of SAR in banana grown under different conditions of exposure to the biotic and abiotic environment. Further, a robust qPCR assay for the study of gene expression using banana leaf samples was developed and a potential inducer of SAR in tissue culture bananas identified which could be harnessed to increase resistance in tissue culture bananas.
20
Rekhter, Dmitrij Aleksandrovic [Verfasser], Ivo [Akademischer Betreuer] Feussner, Ivo [Gutachter] Feussner, Christiane [Gutachter] Gatz, and Yuelin [Gutachter] Zhang. "Metabolic Signals in Systemic Acquired Resistance / Dmitrij Aleksandrovic Rekhter ; Gutachter: Ivo Feussner, Christiane Gatz, Yuelin Zhang ; Betreuer: Ivo Feussner." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2019. http://d-nb.info/1209738473/34.
Full text
21
Chanda, Bidisha. "GLYCEROL-3-PHOSPHATE IS A NOVEL REGULATOR OF BASAL AND INDUCED DEFENSE SIGNALING IN PLANTS." UKnowledge, 2012. http://uknowledge.uky.edu/plantpath_etds/16.
Full textAbstract:
Plants use several strategies to defend themselves against microbial pathogens. These include basal resistance, which is induced in response to pathogen encoded effector proteins, and resistance (R) protein-mediated resistance that is activated upon direct or indirect recognition of pathogen encoded avirulence protein(s). The activation of Rmediated signaling is often associated with generation of a signal, which, upon its translocation to the distal uninfected parts, confers broad-spectrum immunity against related or unrelated pathogens. This phenomenon known as systemic acquired resistance (SAR) is one of the well-established forms of induced defense response. However, the molecular mechanism underlying SAR remains largely unknown. Induction of plant defense is often associated with a fitness cost, likely because it involves reprogramming of the energy-providing metabolic pathways. Glycerol metabolism is one such pathway that feeds into primary metabolism, including lipid biosynthesis. In this study, I evaluated the role of glycerol-3-phosphate (G3P) in host-pathogen interaction. Inoculation with the hemibiotrophic fungal pathogen Colletotrichum higginsianum led to increased accumulation of G3P in wild-type plants. Mutants impaired in biosynthesis of G3P showed enhanced susceptibility, suggesting a correlation between G3P levels and basal defense. Conversely, increased biosynthesis of G3P correlated with enhanced resistance. The Arabidopsis genome encodes one copy of glycerol kinase (GK), which catalyzes phosphorylation of glycerol to G3P, and five copies of G3P dehydrogenase (G3Pdh), which catalyze reduction of dihydroxyacetone phosphate to G3P. Analysis of plants mutated in various G3Pdh's showed that plastidal lipid biosynthesis was only dependent on the GLY1 isoform but the pathogen induced G3P pool required the function of GLY1 and two other G3Pdh isoforms. Interestingly, compromised G3P biosynthesis in GK and G3Pdh mutants also compromised SAR, which was restored when G3P was provided exogenously. Detailed biochemical analysis showed that G3P was transported to distal tissues and that this process was dependent on a lipid transfer protein, DIR1. Together, these results show that G3P plays an important role in both basal- and induced-defense responses.
22
Grant, John J. "A genetic dissection of signal transduction pathways underlying the oxidative burst, cognate redox signalling, and establishment of systemic acquired resistance." Thesis, University of Edinburgh, 2000. http://hdl.handle.net/1842/14932.
Full textAbstract:
Recognition of avirulent microbial pathogens activates an oxidative burst, leading to the accumulation of reactive oxygen intermediates (ROIs), which are thought to integrate a diverse set of defence mechanisms resulting in the establishment of plant disease resistance. Two contrasting experimental strategies were devised to dissect genetic mechanisms governing these signal transduction pathways. Firstly, a novel transgenic Arabidopsis line containing a gstl::luc transgene was developed and employed to report the temporal and spatial dynamics of ROI accumulation and cognate redox signalling in response to attempted infection by avirulent strains of Pseudomonas syringae pv. tomato (Pst). Strong engagement of the oxidative burst was dependent on the presence of functional Pst hrpS and hrpA gene products. Experiments employing specific pharmacological agents suggested at least two distinct sources, including a NADPH oxidase and a peroxidase-type enzyme, contributed to the generation of redox cues. The analysis of gst1::luc gene expression in specific mutant backgrounds suggested engagement of the oxidative burst and cognate redox signalling functioned independently of ethylene, salicylic acid and methyl jasmonate in local RPM1 mediated resistance. In contrast, studies using a panel of specific protein kinase and phosphatase inhibitors revealed mitogen activated protein kinase kinase (MAPKK) activity was required for the activation of the ROI-regulated genes gstl and pall in response to redox cues. Thus the engagement of a redox signalling network dependent on MAPKK activity may contribute to the establishment of plant disease resistance and the development of cellular protectant mechanisms. Secondly, Activation Tagging was employed in conjunction with the reporter gene line Prla::luc, to uncover a mutant with constitutive defence gene expression. This mutant subsequently, named activated disease resistance 1 (adr1), was shown to have enhanced resistance to fungal and bacterial pathogens. adr1 mutants were also shown to have enhanced drought tolerance, and as such are believed to be the first plants engineered with elevated resistance to both disease and drought stress.
23
Zhang, Weizheng. "Disease suppression and systemic-acquired-resistance-induced in plants by compost-amended potting mixes, compost water extracts and no-tillage soil /." The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487943610784806.
Full text
24
Gao, Qing-Ming. "GLYCEROLIPIDS AND THE PLANT CUTICLE CONTRIBUTE TO PLANT IMMUNITY." UKnowledge, 2012. http://uknowledge.uky.edu/plantpath_etds/4.
Full textAbstract:
The conserved metabolites, oleic acid (18:1), a major monounsaturated fatty acid (FA), and glycerol-3-phosphate (G3P) are obligatory precursors of glycerolipid biosynthesis in plants. In Arabidopsis, the SSI2-encoded SACPD is the major isoform that contributes to 18:1 biosynthesis. Signaling induced upon reduction in oleic acid (18:1) levels not only upregulates salicylic acid (SA)-mediated responses but also inhibits jasmonic acid (JA)- inducible defenses. I examined the transcription profile of ssi2 plants and identified two transcription factors, WRKY50 and WRKY51. Although the ssi2 wrky50 and ssi2 wrky51 plants were constitutively upregulated in SA-derived signaling, they were restored in JAdependent defense signaling. Not only did these plants show JA-inducible PDF1.2 expression, but they were also restored for basal resistance to the necrotrophic pathogen, Botrytis cinerea. Overall, my results show that the WRKY50 and WRKY51 proteins mediate both SA- and low 18:1-dependent repression of JA signaling in Arabidopsis plants.
My studies also show that cellular G3P levels are important for plant defense to necrotrophic pathogens. I showed that G3P levels are induced in Arabidopsis in response to the necrotrophic fungal pathogen B. cinerea. G3P-dependant induction of basal defense is not via the activities of other defense-related hormones such as SA, JA or the phytoalexin camalexin. Arabidopsis mutants unable to accumulate G3P (gly1, gli1) showed enhanced susceptibility to B. cinerea.
Previous studies in our lab identified acyl-carrier protein 4 (ACP4), a component of FA and lipid biosynthesis, as an important regulator of plant systemic immunity. ACP4 mutant plants were defective in systemic acquired resistance (SAR) because they contained a defective cuticle. I further investigated the role of the plant cuticle in SAR by studying the involvement of long-chain acyl-CoA synthetases (LACS), a gene family involved in long-chain FA and cuticle biosynthesis, in SAR. In all, eight lacs mutants (lacs1, lacs2, lacs3, lacs4, lacs6, lacs7, lacs8, lacs9) were isolated and characterized. Six mutants were compromised in SAR. Together, my studies show that the various LACS isoforms contribute differentially to both cuticle formation and systemic immunity in Arabidopsis.
25
Bernsdorff, Friederike [Verfasser], Jürgen [Akademischer Betreuer] Zeier, and Michael [Akademischer Betreuer] Feldbrügge. "On the role of amino acids in plant disease resistance: Interplay between pipecolic acid and salicylic acid in plant systemic acquired resistance / Friederike Bernsdorff. Gutachter: Jürgen Zeier ; Michael Feldbrügge." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2015. http://d-nb.info/1069620181/34.
Full text
26
Hutcheon, Carolyn Jamie. "Active oxygen species accumulation in the immunization and manifestation stages of systemic acquired resistance during an arabidopsis thaliana-pseudomonas syringae pv tomato interaction." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0022/MQ40696.pdf.
Full text
27
Oliveira, Perla Novais de. "Transformação genética de tomate \'Micro-Tom\' com o gene enhanced disease susceptibility 5 (EDS5) isolado de Citrus sinensis." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/11/11144/tde-02022016-155536/.
Full textAbstract:
Nos anos recentes, a atividade agrícola da citricultura vem enfrentando grandes problemas fitossanitários, principalmente, com relação à viabilidade econômica decorrente do controle das doenças. A bactéria Candidatus Liberibacter spp. está associada ao HLB, a principal doença que limita a produção das plantas cítricas. Assim, muitos pesquisadores têm voltado suas atenções para estudarem e encontrarem genes-alvo na resposta do hospedeiro a este patógeno para utilização no melhoramento genético. Nesse sentido, métodos de transformação genética das plantas cítricas são essenciais, porém características inerentes à espécie limitam seu cultivo in vitro e requerem um maior tempo para crescimento e propagação. Com isso, torna-se importante o estudo em plantas modelo, principalmente, para seguir protocolos de validação de genes. De acordo com o exposto, o gene EDS5 isolado de Citrus sinensis, associado ao mecanismo de Resistência Sistêmica Adquirida (SAR) foi superexpresso por meio da transformação genética em tomateiro (Solanum lycopersicum L. Micro-Tom). Após o crescimento dos brotos regenerados, foram identificadas as plantas positivas por meio de análise de GUS e PCR. Linhagens transgênicas homozigotas foram obtidas com avaliação da resistência ao antibiótico canamicina.In the recent years, the agricultural activity of the citrus industry has been facing big phytosanitary problems, mainly with regard to economic viability arising from disease control. The bacterium Candidatus Liberibacter spp. is associated with HLB, the main disease that limits the production of citrus trees. Thus, many researchers have been returning their attentions to study and find target genes in the host response to this pathogen for use in the genetic improvement. In this way, methods of genetic transformation of citrus plants are essential, but the inherent characteristics of the species border your in vitro cultivation and require a longer time for growth and propagation. Therefore, it is important to study of model plants, mainly for genetic validation protocols. Thus, the EDS5 gene isolated from Citrus sinensis, associated with Systemic Acquired Resistance mechanism (SAR) was overexpressed by genetic transformation in tomato (Solanum lycopersicum L. Micro-Tom). After the growth of regenerated shoots, positive plants were identified by PCR and GUS analysis. Homozygous transgenic lines were obtained with evaluation of resistance to kanamycin.
28
Wittek, Finni [Verfasser], Jörg [Akademischer Betreuer] Durner, and Wilfried [Akademischer Betreuer] Schwab. "Identification of systemic acquired resistance-inducing molecules in plants by a new metabolomic approach / Finni Wittek. Gutachter: Wilfried Schwab ; Jörg Durner. Betreuer: Jörg Durner." München : Universitätsbibliothek der TU München, 2013. http://d-nb.info/1044680512/34.
Full text
29
Bichlmeier, Marlies [Verfasser], Jörg [Akademischer Betreuer] [Gutachter] Durner, and Wilfried [Gutachter] Schwab. "Identification of Systemic Acquired Resistance–Related Volatile Organic Compounds and their Role in Plant Immunity / Marlies Bichlmeier ; Gutachter: Wilfried Schwab, Jörg Durner ; Betreuer: Jörg Durner." München : Universitätsbibliothek der TU München, 2017. http://d-nb.info/1135385432/34.
Full text
30
Xia, Ye. "THE ROLE OF CUTICLE, FATTY ACIDS, AND LIPID SIGNALING IN PLANT DEFENSE." UKnowledge, 2010. http://uknowledge.uky.edu/plantpath_etds/10.
Full textAbstract:
Systemic acquired resistance (SAR) is initiated upon recognition of specific microbial effectors by cognate plant resistance proteins and immunizes distal tissues of plants against secondary infections. SAR involves the generation of a mobile signal at the site of primary infection, which then translocates to and activates defense responses in the distal tissues via some unknown mechanism(s). This study shows that an ACYL CARRIER PROTEIN 4 (ACP4), GLABRA1 (GL1) and ACYL CARRIER BINDING PROTEINS (ACBP) are required for the processing of the mobile SAR signal in distal tissues of Arabidopsis. Although acp4, gl1 and acbp plants generate the mobile signal, they are unable to respond to this signal to induce systemic immunity. A defective SAR in acp4, gl1 and acbp plants is not associated with salicylic acid (SA)-, methyl SA-, or jasmonic acid-mediated pathways but is related to the presence of an abnormal cuticle on acp4, gl1 and acbp plants. Other genetic mutations impairing the cuticle also compromised SAR. An intact cuticle was only necessary during the time when the mobile signal is generated and translocated to the distal tissues. A novel role for the plant cuticle as the site for SAR-related molecular signaling is demonstrated.
31
Rodrigues, Filipi Augusto Coelho. "Transformação genética de laranjeira doce e de tomateiro Micro-Tom com os genes npr1 e npr3-4 de Citrus sinensis." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/11/11136/tde-03022016-134220/.
Full textAbstract:
A cultura da laranja doce é muito importante ao redor do mundo, em especial no Brasil, maior produtor mundial dessas frutas. A produção citrícola sempre esteve ameaçada por muitas doenças de grande importância, tais como, o cancro cítrico, a clorose variegada dos citros (CVC) e pinta preta. Entretanto, em 2004, surgiu o huanglongbing (HLB) ou greening, que tem devastado pomares, e para a qual ainda não foi encontrada uma solução definitiva. A transgenia pode ser uma técnica auxiliar no manejo desta doença com a busca de cultivares mais tolerantes, em especial ao HLB. Neste trabalho, as pesquisas de transgenia não envolveram genes exógenos à planta como, por exemplo, genes de outros organismos ou genes sintéticos, ou seja, foi baseado em tecnologias mais recentes já aplicadas em outras espécies vegetais, nas quais a transgenia é utilizada para super-expressar genes dos sistemas de defesa da própria planta. Estudos indicam que a super-expressão de genes do sistema de Resistência Sistêmica Adquirida (SAR - do inglês, \"Systemic Acquired Resistance\") promove a resistência de plantas a doenças. Um gene importante para esse sistema é o gene npr1 que controla a expressão das proteínas relacionadas à patogênese (PR), em especial a PR1. Junto do gene npr1, os genes npr3 e npr4 também são reguladores desse sistema, atuando sobre o gene npr1 de acordo com os níveis de ácido salicílico presentes na célula, nível este que varia de acordo com o nível de infecção de cada célula. Porém, a avaliação de um evento transgênico de citros pode levar muitos anos. Desta forma, para diminuir esse tempo de avaliação, pensou-se em usar plantas modelos. O sistema escolhido foi o tomateiro Micro-Tom (Solanun lycopersicum L. cv. Micro-Tom). Para a obtenção das construções gênicas, foram identificados os genes Csnpr1, Csnpr3 e Csnpr4 de Citrus sinensis L. Osbeck a partir dos genes Atnpr1, Atnpr3 e Atnpr4 de Arabidopsis thaliana L.. Os genes de citros foram obtidos a partir de uma planta de laranja doce por RT-PCR e clonados no vetor pCambia 2201, que foi então inserido em Agrobacterium tumefaciens para a transformação genética. Foi feita a transformação genética de plantas de laranja doce (Citrus sinensis L. Osbeck) e do tomateiro Micro-Tom. Após o crescimento dos brotos regenerados, foi feita a avaliação das plantas obtidas por meio de PCR. As plantas geneticamente modificadas foram aclimatizadas. As plantas de citros foram enxertadas e mantidas em casa de vegetação. As plantas de tomateiro Micro-Tom foram propagadas por sementes. A progênie foi avaliada aplicando o antibiótico de seleção canamicina, obtendo-se assim uma linhagem transgênica homozigota.The sweet orange industry is very important worldwide, specially in Brazil, considered the world´s largest producer. The citrus production has always been threatened by several diseases of great importance, such as canker, CVC, and black spot. However, in 2004, the huanglongbing (HLB) or greening has been detected and devastated many citrus groves, and no definitive solution has been found yet. Transgenes may be a helpful tool for the management of this diseases, leading to the production of tolerant cultivars, especially to HLB. In this work, research on transgenic did not include the use of exogenous genes to the plant, such as genes from other organism or synthetic genes, i.e, it was based on new emerging technologies, already used on other crops, in which transgeny is used to super express genes from the plants own defense system. Studies indicate that a super expression of genes from the system called Systemic Acquired Resistance (SAR) promotes disease resistance. One important gene to this system is the npr1 gene, which controls the expression of the pathogen related proteins (PR), in special the PR1. Together with the npr1 gene, the genes npr3 and npr4 are also regulators of this system, regulating the action of the npr1 gene according to the levels of salicylic acid present in the cell, this level varies with the level of infection in each cell. Nevertheless, evaluating a citrus transgenic event may take several years. In order to shorten this time, model plants were used. The model chosen was the Micro-Tom tomato (Solanun lycopersicum L. cv. Micro-Tom). In order to obtain the genetic constructions, the genes Csnpr1, Csnpr3 e Csnpr4 were identified in Citrus sinensis L. Osbeck from the genes, Atnpr1, Atnpr3 and Atnpr4 present in the Arabidopsis thaliana L. genome. The citrus genes were obtained from the citrus genome using RT-PCR procedure and cloned separately into the pCambia 2201 vector, which was inserted into Agrobacterium tumefaciens in order to perform the genetic transformation. Sweet orange (Citrus sinensis L. Osbeck) and Micro-Tom plants were genetically modified. After the growth of the regenerated shoots, the evaluation of the obtained plants was done through PCR analysis. The genetically modified plants were acclimatized, the citrus plants were grafted and kept in the greenhouse, the Micro-Tom plants were propagated trough seeds and its progeny was evaluated by applying the selection antibiotic kanamycin, thus obtaining a homozygous transgenic line.
32
Breitenbach, Heiko [Verfasser], Jörg [Akademischer Betreuer] Durner, and Ralph [Akademischer Betreuer] Hückelhoven. "Identification of new regulators for systemic acquired resistance (SAR) in plants by an integrated proteomics approach / Heiko Breitenbach. Gutachter: Ralph Hückelhoven ; Jörg Durner. Betreuer: Jörg Durner." München : Universitätsbibliothek der TU München, 2013. http://d-nb.info/1036262405/34.
Full text
33
Ramos, Oscar F. "Response of wheat plants (Triticum aestivum L) to stress and synthetic elicitors of systemic acquired resistance as expressed by phenolic levels in foliage and mature grain." Diss., Kansas State University, 2016. http://hdl.handle.net/2097/32922.
Full textAbstract:
Doctor of PhilosophyDepartment of Grain Science and Industry
Ronald L. Madl
Praveen Vadlani
Producers of whole wheat products are interested in marketing the health-promoting benefits of wheat antioxidants. However, they need a steady crop supply with consistent levels of antioxidants. The variable phenolic content in wheat crops is a problem. The objectives of this research were to 1) identify the factor (s) that contribute the most to the variability in phenolic content, 2) understand the mechanism (s) responsible for phenolic synthesis, and 3) artificially trigger that mechanism (s). Phenolics are hypothesized to be part of the defense response of hard red winter wheat (Triticum aestivum L) to stress. The effect of insect feeding, pathogen infection, and heat stress on phenolics in grains from wheat plants cv. Karl 92 was evaluated. Bird-cherry oat aphid (Rhopalosiphum padi) feeding stress significantly explained the variation in phenolic content. Furthermore, the relative allocation of carbon resources to grain yield/phenolic content was influenced by the stage of the plant at which aphid feeding started to occur. Based on these findings, phenolics were hypothesized to be an active defense response acting through a mechanism known as systemic acquired resistance (SAR). In order to prove this hypothesis, several synthetic elicitors of SAR were tested for their effectiveness at inducing de novo phenolic synthesis in wheat foliage and in mature grains. Elicitors that acted through the salicylic- and jasmonic acid signaling pathways were effective at inducing phenolic synthesis by 49% and 177%, respectively, in the leaves 36 hours post spray application. They also elicited a phenolic response in mature grains of up to 21% induction. Enhancement of the levels of naturally occurring phenolic compounds with antioxidant activity in wheat grains through SAR activation is a value addition strategy that can potentially increase the profitability of hard red winter wheat crops. It can also provide manufacturers of whole wheat with natural antioxidants that can potentially be used to substitute their synthetic counterparts in wheat based products.
34
Eddo, Alexander. "Characterization of the Pathway Leading to the Synthesis of Salicylic Acid in Plants Resisting Pathogen Infection." Digital Commons @ East Tennessee State University, 2008. https://dc.etsu.edu/etd/1958.
Full textAbstract:
Salicylic acid is a plant hormone that accumulates with plant-pathogen interaction. This accumulation corresponds to the plant being resistant to infection and without it the plant is susceptible. In this study, primers of genes involved in the normal synthesis of SA were used in RT-PCR to compare gene expression levels in susceptible and resistant plants challenged with tobacco mosaic virus. Because SA synthesis shares chorismate as a common substrate with the synthesis of aromatic amino acids, HPLC was used to determine whether the increase in SA could be attributed to a decrease in amino acid levels. The results suggest that genes of the shikimate pathway are up-regulated in both plant lines but much more quickly in the resistant plant, making differential gene expression a possible cause of SA accumulation. Additionally, results showed a more pronounced decrease in amino acid levels in resistant plants compared to susceptible plants.
35
Moreira, Soares Juliana. "ROLE OF GLYCEROL-3-PHOSPHATE PERMEASES IN PLANT DEFENSE." UKnowledge, 2018. https://uknowledge.uky.edu/plantpath_etds/23.
Full textAbstract:
Systemic acquired resistance (SAR) is a type of plant defense mechanism that is induced after a localized infection and confers broad-spectrum immunity against related or unrelated pathogens. During SAR, a number of chemical signals and proteins generated at the site of primary infection travel to the uninfected tissues and are thought to alert the distal sites against secondary infections. Glycerol-3-phosphate (G3P) is one of the chemical signals that play an important role in SAR. G3P is synthesized in the cytosol and chloroplasts via the enzymatic activities of G3P Dehydrogenase (G3Pdh) or Glycerol Kinase (GK). Interestingly, a mutation in three of the five G3Pdh isoforms or GK impairs SAR by lowering the pathogen induced G3P pool. This suggests that total cellular pool of G3P is critical for SAR. To determine factors contributing to G3P flux between various subcellular compartments I analyzed the role of putative G3P transporters in G3P flux and SAR. The Arabidopsis genome encodes five isoforms of G3P Permeases (G3Pp) and these transmembrane proteins are predicted to localize to plasma membrane, chloroplast or mitochondria. At least two G3Pp isoforms (G3Pp1 and G3Pp3) were able to complement the Escherichia coli mutant impaired in the uptake of G3P into the cytoplasm. Characterization of Arabidopsis G3Pp mutants showed that a mutation in G3Pp2, G3Pp3 and G3Pp4 compromised SAR but not local resistance. Furthermore, this SAR defect could only be complemented by exogenous application of G3P. The G3Pp mutants accumulated wild-type-like levels of G3P suggesting that the subcellular compartmentalization of G3P might contribute to the induction of SAR.
36
Pabst, Elisabeth Sophie [Verfasser], Jörg [Akademischer Betreuer] Durner, Jörg [Gutachter] Durner, and Erich [Gutachter] Glawischnig. "Arabidopsis thaliana legume lectin-like proteins at the interface between systemic acquired resistance and abiotic stress responses / Elisabeth Sophie Pabst ; Gutachter: Jörg Durner, Erich Glawischnig ; Betreuer: Jörg Durner." München : Universitätsbibliothek der TU München, 2018. http://d-nb.info/1161528547/34.
Full text
37
Chapagai, Danda P. "Biochemical Characterization of SBIP-470 and its role in SA-mediated Signaling in Plants." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etd/2428.
Full textAbstract:
Salicylic acid binding protein 2 (SABP2) is known to play a key role in Salicylic acid mediated defense pathway. SBIP-470 is SABP2 interacting protein that might be putatively involved in transfer of lipids. SBIP-470 was cloned without the signal peptide and expressed in E. coli. In vitro lipid binding assay using recombinant SBIP-470 failed to detect lipid binding. In vitro lipid transfer assay showed recombinant SBIP-470 does not transfer phospholipid. Study has shown that SBIP-470 is highly inducible upon infection with viral as well as bacterial pathogens. Induction of SBIP-470 expression upon the TMV infection most likely depends upon the SABP2 while its expression upon non-host bacterial pathogens is most probably inhibited by the SABP2. A study of Arabidopsis knockout mutants (ltp12 mutant and ltp2 mutant) lacking the SBIP-470 homolog genes showed defects in growth phenotype, and they were found susceptible to bacterial pathogens.
38
Vitalini, S. "EFFECT OF SAR INDUCERS ON GRAPE SECONDARY METABOLITES." Doctoral thesis, Università degli Studi di Milano, 2012. http://hdl.handle.net/2434/168721.
Full textAbstract:
Fungicide application is now the most efficacious method for controlling plant diseases caused by oomycetes and fungi. As legislation is limiting and reducing their use, it is strongly stimulating studies for the identification of additional and environmentally friendly approaches in the control of their associated diseases. Among these, systemic acquired resistance (SAR) offers the prospect of long-lasting, broad-spectrum disease control through activation of the resistance defence machinery of the plant itself. Plant activators are products employed in crop protection able to elicit SAR. Therefore, they may trigger the plant own defence response against pathogen attacks, mainly stimulating mechanisms such as the biosynthesis of phytoalexins, plant secondary metabolites with a broad spectrum biological activity. In this study, two plant defence inducers, benzothiadiazole (BTH) and chitosan (CHT), deserving particular attention because of their efficacy and low toxicity, have been used. CHT is a natural and low-cost polymer (from the waste products of the crustacean carapace), obtained by chitin deacetylation. Its effectiveness is higher when molecular weight is between 10 and 100 kD and the deacetylation degree range is from 80 to 90 percent. BTH [benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester] is a synthetic compound and a functional analogue of salicylic acid, a plant hormone-like compound deeply involved in resistance against pathogens. Two different phytoiatric campaigns were planned, in 2009 and 2010, on two red grapevine (Vitis vinifera L.) varieties cultivated in experimental vineyards located at distinct sites: Groppello, an autochthonous cultivar of Lombardia, at Raffa di Puegnago (Brescia), and Merlot at Conegliano Veneto (Treviso). Open field treatments carried out on Groppello grapevines were: i) 0.03% (w/v) CHT (76 kDa molecular weight and 85% deacetylation degree), ii) 0.03% CHT in combination with 150 g hL-1 copper hydroxide (CHT/Cu) and iii) 0.3 mM BTH; whereas, on Merlot, besides CHT and CHT/Cu, BTH were replaced by 300 g hL-1 potassium phosphites. Untreated vines were used as negative control, while plants treated with conventional fungicides (penconazole and methyldinocap) were the positive control. In both field surveys, the trial was set up as a complete randomized block design in 4 replications, with 10 vines (a parcel) per treatment in each block. Plants were sprayed approximately every 10 days, according to the meteorological conditions, from the beginning of grape susceptibility to fungal diseases until the complete véraison. The phytosanitary status of vineyards was assessed weekly on leaves and bunches, by visual inspections, though both sites were not particularly predisposed to severe fungal or other epidemics. The epidemiological evaluations were performed on bunches alone and infection indexes were calculated. All the treatments were effective in controlling fungal infections (downy mildew, Plasmopara viticola and powdery mildew, Erysiphe necator), in terms of disease incidence (I %), disease severity (S %) and infection degree (ID %), though these indexes were low in untreated control grapevines, particularly in 2010. Sampling was scheduled at two phenological phases: pre-véraison and 100% véraison; bunches were randomly collected from plants during the morning and stored at -20 °C until analyses. Berry tissues were separated into skin, flesh and seeds, powdered and extracted. Then, extracts were tested to evaluate their melatonin levels [by ultra performance liquid chromatography (UPLC)-MS/MS], total polyphenols (TP, by Folin-Ciocalteau assay) and antiradical activity [by DPPH, 2,2-diphenyl-1-pycryl hydrazyl and ABTS, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) assay]. Groppello and Merlot experimental wines were produced, by standard microvinification techniques, in the Centro Vitivinicolo Provinciale of Brescia and Centro di Ricerca per la Viticoltura of Conegliano (TV), respectively, and stored at 4 °C in the dark until analyses. Microvinificates were produced from grapes treated with both elicitors and conventional fungicides (controls), and the following analyses, besides those also conducted for all berry tissues, were carried out: tryptophan, serotonin and melatonin detection (by UPLC-MS/MS); content of cis and trans resveratrol (by UPLC-MS/MS); levels of mycotoxins (manly ochratoxin A, OTA, by UPLC-MS/MS). In general, berry tissues treated with elicitors and the corresponding experimental wines showed higher levels of melatonin and polyphenols, as well as a higher antiradical activity than samples treated with conventional fungicides. High concentrations of tryptophan were detected in all samples, contrary to serotonin, which was not detected. The most effective elictors were CHT/Cu and CHT. In all wines, the level of OTA was below the allowable threshold of 2 ng/mL. To the best of our knowledge, these results represent the first data on the effects of agrochemicals on the melatonin content of red wine, and the presence of melatonin was reported, for the first time, in berry seeds and flash, after its previously detection in skin. Furthermore, the level of the indolamine in berry tissues varies according to the phenological stage, resulting more abundant in seed at pre-véraison and in skin at véraison. The good agreement between the data obtained in 2009 and 2010 for Groppello cultivar, and, in 2009, between Groppello and Merlot varieties cultivated in different geographical areas, suggests that, in general, plant activators may improve some qualitative/healthy treats ascribed to red wine, though their efficacy in controlling grapevine fungal diseases should be better ascertained. Finally, the role of melatonin, a powerful antioxidant, in grapevine physiology is still somewhat obscure. It is possible that, at pre-véraison, when skin anthocyanic pigmentation is still lacking, this compound may defend berry from damage due to photooxidation or UV radiation, whereas, at véraison, the indolamine may protect the germ tissues, particularly rich in storage lipids and membranes and vulnerable to oxidative damage. In conclusion, the possibility of enhancing the pharmaconutritional potential of grape/wine with phytosanitary treatments should be further tajen into account.
39
Augusti, Guilherme Rossato. "Progresso de phakopsora pachyrhizi em função do estádio fenológico e da idade de trifólios em soja." Universidade Federal de Santa Maria, 2012. http://repositorio.ufsm.br/handle/1/5064.
Full textAbstract:
Fungicide use with different mechanisms of action as well the pulverization moment
are the factors to be considered on the asian soybean rust control. Since many
products have shown lost of efficiency, emerges the need of new alternatives to the
control of soybean rust. The study aimed to quantify the effect of the systemic
resistance inducer Acibenzolar-S-Methyl and the combination of fungicides
molecules of the triazole + strobilurin + carboxamide applied in different stages in
relation to the soybean rust control and yield. Two field experiments were conducted
in greenhouse on the harvest year of 2010/2011. The experiment 1, with the
pathogen inoculation at the phenological stage R5.1, was performed on factorial
scheme (2x5x6), and the factors consisted of: Factor A: two soybeans cultivars (BMX
Potência RR and Coodetec 219 RR); Factor D: treatments with Acibenzolar-S-Methyl
(12,5 g a.i.ha-1), Azoxystrobin + Cyproconazole (60 + 24 g a.i.ha-1), Acibenzolar-SMethyl
+ Azoxystrobin + Cyproconazole (12,5 + 60 + 24 g a.i.ha-1), Pyraclostrobin +
Epoxiconazole + Fluxapyroxad (64,8 + 40 + 40 g a.i.ha-1) and a testimony trait in
each cultivar; factor E: Application of the treatments at the stages V6, R1, R5.1, 10,
17 and 24 days after the artificial inoculation (DAI) of Phakopsora pachyrhizi. The
experiment 2, with the pathogen inoculation at the stage R1 was performed in
factorial scheme (2x5x5) differing from the experiment 1 only on the factor E:
application of the treatments in R1, 5, 10, 17 and 24 days after the inoculation. Was
evaluated the area under the disease progress curve and the number of days to the
appearance of the first pustule in leaflets of three distinct ages, also the average
weight of seeds per experimental unit. The treatments presented differentiated
behavior when exposed to different combinations between the cultivars, application
period and leaflets age. Generally the combinations of Acibenzolar-S-Methyl +
Azoxystrobin + Cyproconazole and Pyraclostrobin + Epoxiconazole + Fluxapyroxad
resulted in better disease control and higher soybeans yield at the earlier and late
applications in relation to the pathogen inoculation moment, without differing of
Azoxystrobin + Cyproconazole in the others application moments.O uso de fungicidas com diferentes mecanismos de ação, assim como a época de aplicação dos mesmos, são fatores que devem ser levados em consideração para o controle da ferrugem asiática na soja. Uma vez que muitos produtos têm apresentado perda de eficiência, surge a necessidade de novas alternativas de controle dessa doença. Com este trabalho buscou-se quantificar o efeito do uso do indutor de resistência Acibenzolar-S-Metil e da mistura de moléculas fungicidas dos grupos triazol + estrobilurina + carboxamida aplicados em diferentes épocas do ciclo da cultura em relação ao controle da ferrugem asiática e produtividade da soja. Para isso dois experimentos foram executados em estufa plástica na safra agrícola 2010/2011. O experimento 1, com a inoculação do patógeno no estádio fenológico R5.1, foi realizado em arranjo fatorial (2x5x6), cujos fatores foram compostos por: fator A: duas cultivares de soja (BMX Potência RR e Coodetec 219 RR); fator D: tratamentos com Acibenzolar-S-Metil (12,5 g i.a.ha-1), Azoxistrobina + Ciproconazol (60 + 24 g i.a.ha-1), Acibenzolar-S-Metil + Azoxistrobina + Ciproconazol (12,5 + 60 + 24 g i.a.ha-1), Piraclostrobina + Epoxiconazol + Fluxapyroxad (64,8 + 40 + 40 g i.a.ha-1) e um tratamento testemunha em cada cultivar; fator E: aplicação dos tratamentos em V6, R1, R5.1, 10 , 17 e 24 dias após a inoculação (DAI) artificial de Phakopsora pachyrhizi. O experimento 2, com a inoculação do patógeno no estádio fenológico R1, foi realizado em arranjo fatorial (2x5x5) diferindo-se do experimento 1 apenas para o fator E: aplicação dos tratamentos em R1, 5, 10 , 17 e 24 dias após a inoculação (DAI). Avaliou-se a área abaixo da curva de progresso da doença (AACPD) e o número de dias para aparecimento da primeira pústula em trifólios de três idades distintas, além do peso de grãos por parcela. Os tratamentos apresentaram comportamento diferenciado quando expostos a diferentes combinações entre cultivares, épocas de aplicação e idade de trifólios. De modo geral as misturas de Acibenzolar-S-Metil + Azoxistrobina + Ciproconazol e Piraclostrobina + Epoxiconazol + Fluxapyroxad resultaram em melhor controle da doença e maior produtividade de soja nas aplicações mais precoces e tardias em relação ao momento da inoculação do patógeno, não diferindo de Azoxistrobina + Ciproconazol nas demais épocas de aplicação dos tratamentos.
40
El-Shetehy, Mohamed H. "Molecular and Biochemical Signaling Underlying Arabidopsis-Bacterial/Virus/Fungal Interactions." UKnowledge, 2016. http://uknowledge.uky.edu/plantpath_etds/19.
Full textAbstract:
Systemic acquired resistance (SAR) is a form of inducible defense response triggered upon localized infection that confers broad-spectrum disease resistance against secondary infections. Several factors are known to regulate SAR and these include phenolic phytohormone salicylic acid (SA), phosphorylated sugar glycerol-3-phosphate (G3P), and dicarboxylic acid azelaic acid (AzA). This study evaluated a role for free radicals nitric oxide (NO) and reactive oxygen species (ROS) in SAR. Normal accumulation of both NO and ROS was required for normal SAR and mutations preventing NO/ROS accumulation and/or biosynthesis compromised SAR. A role for NO and ROS was further established using pharmacological approaches. Notably, both NO and ROS conferred SAR in a concentration dependent manner. This was further established using genetic mutants that accumulated high levels of NO. NO/ROS acted upstream of G3P and in parallel to SA. Collectively, these results suggest that NO and ROS are essential components of the SAR pathway.
41
Yuh, Joannes Petrus. "Effect of Pesticides on Salicylic Acid Binding Protein 2 (SABP2) and Plant Defense." Digital Commons @ East Tennessee State University, 2011. https://dc.etsu.edu/etd/2259.
Full textAbstract:
Tobacco SABP2 has been shown to display high affinity for salicylic acid (SA) and methylsalicylate (MeSA) and plays an important role in SAR signal development. Using biochemical approach, SABP2 has been shown to demonstrate strong esterase activity in converting MeSA to SA. Recent study shows that tetra fluoroacetophenone, a synthetic analog of SA, competitively inhibits SABP2 esterase activity as well as suppresses SAR signal development in tobacco mosaic virus (TMV)-infected tobacco plants. Not much has been studied on the effect of pesticides on plant defenses. Because both AChE and SABP2 are esterase-like proteins belonging to α/β hydroxylase superfamily, we hypothesize that pesticides may inhibit the MeSA esterase activity of SABP2 and block SAR development. Biochemical and molecular biology techniques were used to test this hypothesis. SAR in tobacco-TMV plant-pathogen system is measured by significant decrease in TMV-induced lesion sizes in secondarily inoculated distal leaves.
42
Hossain, Mir Ashad. "Does SABP2 Exist As a Dimer?" Digital Commons @ East Tennessee State University, 2011. https://dc.etsu.edu/etd/2255.
Full textAbstract:
Salicylic acid binding protein 2 (SABP2) is one of the key enzymes in salicylic acid-dependent plant defense pathway. SABP2 is a 29 kDa protein present in extremely low abundance in plants and it catalyzes the conversion of signaling molecule methyl salicylate into salicylic acid. Although it has been shown that 6x His-tagged SABP2 over expressed in E. coli is a homodimer, its exact conformation in planta is still unknown. Therefore, we proposed to determine if SABP2 exist as a dimer and/or monomer under natural condition. To verify the exact conformation of native SABP2 protein in plant, SABP2 was purified from wild type tobacco using a 5-step purification protocol. Analysis of purified SABP2 in gel filtration and immunoblot assay suggested that SABP2 exists as a monomer in tobacco plant. Studies on SABP2 conformation will give us insight into the structure and functional relationship of this protein in salicylic acid-dependent disease resistance pathway.
43
Fai, Leonard Yenwong. "Subcellular Localization of Tobacco Salicylic Acid Binding Protein 2 in Plants." Digital Commons @ East Tennessee State University, 2011. https://dc.etsu.edu/etd/1274.
Full textAbstract:
Salicylic Acid Binding Protein 2 (SABP2) is a 29kDa protein present in extremely low amounts in tobacco leaves. SABP2 processes the mobile defense signal, methyl salicylic acid generated in plants resisting microbial infection. The precise localization of SABP2 in plants is not known. SABP2 has not been shown to have any targeting signal peptides. This study was designed to determine localization of SABP2 in tobacco plants. Biochemical and immunological studies using antibodies against SABP2 suggest that it is localized to the chloroplast, associating with chloroplast envelope membranes. Chloroplast import assays confirm that SABP2 is associated with the chloroplast envelope membrane. Solubilization and analysis of chloroplast membrane proteins show that imported SABP2 associates with the chloroplast envelope membrane by weak hydrophobic and/or ionic interactions. Cellular localization and understanding mechanisms of SABP2 import to the chloroplast will be important from a metabolic engineering standpoint to enhance plant natural defense against microbial pathogens.
44
Chapuis, Sophie. "Contribution à l’étude du mouvement systémique de deux phytovirus : analyse comparative du transcriptome de cellules compagnes infectées et saines." Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAJ041/document.
Full textAbstract:
Les phytovirus empruntent les vaisseaux du phloème pour envahir leur plante hôte de manière systémique. Ce mouvement étant très mal connu, l’objectif de cette étude était d’identifier par une approche transcriptomique, des gènes spécifiquement dérégulés dans les cellules compagnes (CC) suite à l’infection virale par un Polerovirus, le Turnip yellows virus (TuYV) ou par un Potyvirus, le Lettuce mosaic virus (LMV). Pour ce faire, des protoplastes de CC ont été préparés et triés par la technologie de FACS. Les ARN extraits ont ensuite été traités par RNAseq et hybridation sur puces CATMA. Malgré d’importantes variations entre les expériences, nous avons identifié des processus biologiques communs affectés par les infections virales : la voie d’assimilation du soufre et le mécanisme de résistance systémique acquise (SAR) pour le LMV, et la voie de biosynthèse des glucosinolates pour le TuYV. Pour compléter cette étude, une banque d’ADNc spécifique des CC a été construite et criblée en utilisant le domaine C-terminal de la protéine RT du TuYV. Une interaction avec la protéine CIPK7 a été détectée et le rôle potentiel de cette interaction dans le cycle viral a été étudié in plantaPhytoviruses invade systemically their host plant through the phloem. As this viral step remains poorly understood, the aim of this work was to identify, using a transcriptomic approach, genes specifically deregulated in companion cell (CC) during infection with the Polerovirus Turnip yellows virus (TuYV) and the Potyvirus Lettuce mosaic virus (LMV). CC protoplasts were prepared and sorted by FACS technology. Extracted RNA were further analyzed by RNAseq andCATMA microarrays. Although considerable variations between the experiments were observed,we were able to identify common biological processes affected by viral infections: sulfate assimilation and systemic acquired resistance (SAR) mechanism for LMV and glucosinolate biosynthesis for TuYV. To complete this study on systemic viral movement, a CC-specific cDNA library was constructed and screened using the TuYV RT C-terminal domain as a bait. An interaction with the AtCIPK7 protein was retrieved, a protein kinase interacting with calcineurin Blike proteins. The potential role of this interaction in the viral cycle in planta was further investigated in planta
45
Christopher, Stephen James. "Plant-pathogen interactions: turnip crinkle virus suppression of the hypersensitive response in arabidopsis thaliana." Link to electronic thesis, 2003. http://www.wpi.edu/Pubs/ETD/Available/etd-0429103-084755.
Full textAbstract:
Thesis (M.S.)--Worcester Polytechnic Institute.Keywords: Turnip crinkle virus; arabidopsis; thaliana; TCV; avrRpt2; avrRpm1; avrRps4; systemic acquired resistance; virulence; Avr gene; R gene; pseudomonas syringae. Includes bibliographical references (p. 60-66).
46
Dufour, Marie-Cécile. "Etude de l'efficacité des défenses de différents génotypes de Vitis induites par élicitation face à la diversité génétique de bioagresseurs (Plasmopara viticola et Erysiphe necator) : du gène au champ." Thesis, Bordeaux 2, 2011. http://www.theses.fr/2011BOR21847/document.
Full textAbstract:
La vigne est soumise à la pression de nombreux bioagresseurs dont des parasites obligatoires tels que l’oïdium et le mildiou. La lutte contre les maladies causées par les pathogènes biotrophes nécessite une utilisation souvent intensive de fongicides. Le vignoble consomme à lui seul 16% des fongicides commercialisés chaque année en France. Pour réduire leur impact environnemental qui conduit à l’acquisition de la résistance aux pesticides des pathogène et la présence de résidus dans les vins et dans l’atmosphère, des efforts doivent être entrepris pour développer des stratégies de protection innovante de remplacement ou complémentaire permettant de réduire les intrants pesticides.Les stimulateurs des défenses des plantes permettent de limiter le développement des bioagresseurs en conditions contrôlées. Toutefois, leurs efficacités in natura sont variables et souvent décevantes. Suite au grand nombre de produits potentiellement stimulateurs des défenses des plantes, et à l’intérêt que leur portent les viticulteurs, il est nécessaire de disposer de connaissances et d’outils qui permettent d’évaluer leus efficacités et mieux connaitre leurs potentiels de protection du vignoble. Pour ce faire, une méthode d’évaluation de l’efficacité de produits potentialisateurs ou éliciteurs a été développée au niveau biologique, moléculaire (expression de gènes impliqués dans les défenses) et biochimique (analyses qualitatives et quantitatives des polyphénols), nommée "BioMolChem". Cette méthode a permis d’évaluer l’efficacité de deux phosphonates et d’un analogue de l’acide salicylique, sur différents génotypes et phénotypes de mildiou de la vigne et d’oïdium. Cette approche méthodologique "BioMolChem" a permis d’établir des corrélations entre l’expression de gènes de défense, la présence de certains stilbènes et une efficacité des défenses de Vitis vinifera cv. Cabernet-Sauvignon vis-à-vis de l’oïdium et du mildiou. Les modifications des patrons d’expression des 19 gènes suivis dans les feuilles de vigne et les profils HPLC de polyphénols révèlent des mécanismes de défense multigéniques et complexes. Ainsi, les réactions de défense de la plante sont-elles modulées, en fonction de l’éliciteur considéré, mais aussi en fonction de la diversité phénotypique et génétique des agents pathogènes contre lesquels elle se défend. Ces défenses se caractérisent par une sur-expression d’un ensemble de gènes de défense et une accumulation de composés phénoliques spécifiques.Les marqueurs (gènes et molécules) ainsi identifiés, la méthode "BioMolChem" a été appliquée in natura et a conforté, pour partie, les résultats obtenus au laboratoire. Dans des conditions de fortes pressions parasitaires, il est donc possible de protéger les feuilles et les grappes, à l’aide de SDP et des essais d’association ou d’alternance avec des fongicides conventionnels montrent l’intérêt potentiel de l’emploi des SDP au vignoble. Chemin faisant, dans le cadre d’une viticulture innovante et durable, les SDP et la méthode "BioMolChem" ont été appliqués sur des génotypes hybrides (Vitis vinifera x Muscadinia rotundifolia). Nous révélons que selon le niveau de résistance intrinsèque des génotypes (plus ou moins résistants à l’oïdium et au mildiou), il est possible d’augmenter le niveau de la résistance exprimée par élicitation. Ainsi, les SDP pourraient-ils s’avérer des alliés d’intérêt pour l’utilisation de variétés partiellement résistantes et limiter potentiellement le contournement des QTL de résistance. L’ensemble de ce travail, à but appliqué, a conduit à l’obtention de résultats qui nous permettent de mieux comprendre comment la vigne réagit aux SDP dans son environnement agronomique. Leur exploitation et leur finalisation devraient nous permettre d’exploiter et de mettre en place une utilisation des éliciteurs mieux adaptée, à des stratégies alternatives ou complémentaires de la gestion des bioagresseurs de la vignePowdery (Erysiphe necator) and downy mildew (Plasmopara viticola) are very important grapevine diseases (Vitis vinifera). These two biotrophic pathogens, which are native to the United States, infect green vine tissues and cause significant economic loss as well as environmental damage through the repetitive applications of fungicides. To reduce their environmental impact efforts should be made to develop strategies to protect innovative alternative or complementary to reduce pesticide inputs.In this study, the efficacy and the role of Benzothiadiazole (BTH), a salicylic acid analogue, and two phosphonate derivatives strengthen plant defence mechanisms against various isolates of downy and powdery mildews (Plasmopara viticola and Erysiphe necator). These compounds showed differences in their efficacy depending on the variability of mildews and highly dependent on plant genetics, environmental conditions and selection pressure. The plant defense stimulation could be an alternative or additional method to traditional pest management in the grapevine.Tools “BioMolChem” were developed to better assess the defence status of the plant defences in vitro and in natura. Transcript kinetics of selected defence-related genes and polyphenol contents profiles, during Vitis vinifera-biotrophic pathogen interaction, were characterized, and the impact of pathogen diversity was investigated in the absence or presence of elicitation. In vineyard, under strong pathogen pressures, it is thus possible to protect leaves and clusters, with SDP and assays of association or alternation with conventional fungicides show the potential interest of the use of these SDP in the vineyard.The grapevine defense mechanisms are complex, depending on the elicitor, leading to the coordinated accumulation of pathogenesis-related proteins (PR), the production of phytoalexins, and the reinforcement of plant cell walls.On the way, within the framework of an innovative and sustainable viticulture, the SDP was applied to hybrid genotypes (V. vinifera x M. rotundifolia). We reveal that according to the level of intrinsic resistance of the genotypes (more or less resistant to powdery and to downy mildew), it is possible to increase the level of the expressed resistance. The SDP could become allies of interest in the use of partially resistant grapevine varieties.The present findings provide insights into the potential use of transcripts and stilbenes as markers of the defense status of grapevine leaves with or without elicitation or infection, which should allow us to exploit and develop a better use of elicitors in alternative or complementary strategies in grapevine pest management
47
Qiu, Xiaohui. "Papaya systemic acquired resistance." 2003. http://proquest.umi.com/pqdweb?index=1&did=764805031&SrchMode=1&sid=3&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1233277258&clientId=23440.
Full text
48
Chung, Jui-Chou, and 鍾瑞洲. "Systemic Acquired resistance in Lily." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/06657532118491671602.
Full textAbstract:
碩士國立臺灣大學
植物病理學研究所
87
Infection of Botrytis elliptica was able to induce systemic acquired resistance in lily. Lesion numbers decreased in the upper and lower systemic leaves that were challenged with B. elliptica at three or five day post first inoculation. However, the lesion size was not affected compared to that in control leaves. The content of salicylic acid (SA) in lily leaves of first inoculation increased after one day incubation and maintained at higher level for six days. SA content was not increased in upper and lower systemic leaves. However, upon challenge inoculation, the SA content increased in upper and lower systemic leaves. On the other hand, one or two week(s) after planted in Rhizoctonia solani-infested soil, lesion number of lily caused by B. elliptica increased. The SA content in the leaves of R. solani-infected lily plants increased, however, after challenged by B. elliptica, the SA level in the leaves of R. solani-infected lily plant was no more increased. When exogenous SA was sprayed on abaxial surface of lily leaves or dripped in the rhizosphere of lily plants, resistance of lily to B. elliptica was observed. In the dripping application, the resistance lasted longer and the SA content in lily leaves increased. Different cultivars and part of leaves of lily showed difference in the susceptibility to B. elliptica and the SA content. Oriental hybrid cv. Star Gazer displayed higher susceptibility to B. elliptica, Oriental hybrid cv. Simplon and cv. Casablanca and asiatic hybrid cv. Gelria showed medium susceptibility, longiflorum hybrid cv. Elite showed least susceptibility. However, the SA contents were highest in cv. Casablanca, less in cv. Simplon, cv. Star Gazer and cv. Elite, and least in cv. Gelria. On the other hand, the middle leaves of three-, four-, or five-week-old lily plants of Oriental lily cv. Star Gazer showed similar of the susceptibility to B. elliptica and the SA level. The upper leaves of Oriental lily cv. Star Gazer displayed less susceptibility to B. elliptica compared to the middle and lower leaves, however, the SA contents in different parts of lily appeared similar. In molecular biology study, two primer pairs, 52/64 and 96/97, which were able to differentially amplify DNA fragments of predicted size from SA treated and B. elliptica-infected lily leaves, were used to generate RT-PCR products of about 550 bp and 300 bp, respectively. These DNA fragments were cloned and designated as lily-204 and lily-206. The nucleotide sequence of lily-204 showed 99% homology with that of alkyphosphonate uptake J gene (phn J), the amino acid sequence of lily-206 displayed 35% similarity to that of a calcium-binding protein. Northern hybridization analysis indicates that the transcripts corresponding to probe 204 was accumulated three days post inoculation of B. elliptica, the transcripts were detected earlier in lily leaves that had bean sarayed with SA solution at one day post inoculation. The signal maintained at high level for three days. However, no transcripts corresponding to probe 204 was detected in lily leaves sprayed with SA solution. The transcripts corresponding to probe 206 was accumulated in lily leaves in response to infection by B. elliptica, but was not detected in SA-treated leaves with or without challenge of B. elliptica
49
Rekhter, Dmitrij Aleksandrovic. "Metabolic Signals in Systemic Acquired Resistance." Thesis, 2019. http://hdl.handle.net/21.11130/00-1735-0000-0003-C19F-0.
Full text
50
Chen, Yen-Chu, and 陳彥竹. "A benzothiadiazole derivative (BTH) induces systemic acquired resistance (SAR) in Chrysanthemum." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/70570832073177928428.
Full textAbstract:
碩士輔仁大學
生命科學系碩士班
101
Chrysanthemum (Chrysanthemum morifolium) is one of the world's three major cut flowers and one of the most important economical flowers in Taiwan. However, chrysanthemum has many diseases, for example, bacterial soft rot which vastly affects yield. This disease is caused by the gram-negative bacterium Pectobacterium chrysanthemi (Erwinia chrysanthemi), which infects host through wounds in young organs and resulted in extended necrosis of infected tissues. Using general pesticide can only reduce the rate of symptoms development but not to cure it. In order for plant to effectively fight against broad spectrum of pathogens and thrive in nature, the best strategy is to activate their de novo systemic resistant ability. Systemic acquired resistance (SAR) is an inducible defense response found in a large range of plant species when encountered biotic and abiotic stresses. Activation of NPR1 transcription factor will be triggered by SA accumulation, and resulted in cascade defense responses performed by pathogenesis-related (PR) gene products. The benzothiadiazole derivative acibenzolar-S-methyl (BTH), a well-known chemical activator of SAR response was used in this study to evaluate its ability to potentiate resistance in chrysanthemums. We found that 2.4mM is the optimal concentration to induce NPR1-like gene expression in chrysanthemum. Five days after treating with BTH, the glucanase and chitinase activity increase 2.6-fold and 19-fold, respectively, compared to untreated control. When challenged with P. chrysanthemi, the necrotic area of BTH-treated leaf was 7-fold smaller compared to untreated control. In addition, we have also found that if treated lower leaves of a plant with BTH in advance can enhance the resistance ability in the upper leaves. In summary, we conclude that the BTH can induce SAR resistance in chrysanthemums.