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Daniel J. Kliebenstein - One of the best experts on this subject based on the ideXlab platform.
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Orchestration of Plant Defense systems: genes to populations
Trends in plant science, 2014Co-Authors: Daniel J. KliebensteinAbstract:Research over the past decades has made immense progress in identifying some genes and mechanisms underlying Plant Defense against biotic organisms. The recent movement towards systems biology approaches has increased mechanistic knowledge, revealing a need for understanding how all the genes and mechanisms integrate to create a response to any given biotic interaction. This begins with evidence that diverse molecular patterns converge, suggesting that the Plant perceives signals not the interacting species. These signals then coordinate across regulatory networks via molecular interactions and cause non-cell autonomous responses in neighboring and systemic cells. Finally, the identification of transporters is showing that Plant Defenses are harmonized across tissues and even show the potential for coordination across individuals within a population.
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Plant Defense Compounds: Systems Approaches to Metabolic Analysis
Annual review of phytopathology, 2012Co-Authors: Daniel J. KliebensteinAbstract:Systems biology attempts to answer biological questions by integrating across diverse genomic data sets. With the increasing ability to conduct genomics experiments, this integrative approach is being rapidly applied across numerous biological research communities. One of these research communities investigates how Plants utilize secondary metabolites or Defense metabolites to defend against attack by pathogens and other biotic organisms. This use of systems biology to integrate across transcriptomics, metabolomics, and genomics is significantly enhancing the rate of discovery of genes, metabolites, and bioactivities for Plant Defense compounds as well as extending our knowledge of how these compounds are regulated. Plant Defense compounds are also providing a unique proving platform to develop new approaches that enhance the ability to conduct systems biology with existing and previously unforseen genomics data sets. This review attempts to illustrate both how systems biology is helping the study of Plant Defense compounds and vice versa.
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deficiencies in jasmonate mediated Plant Defense reveal quantitative variation in botrytis cinerea pathogenesis
PLOS Pathogens, 2010Co-Authors: Heather C. Rowe, Katayoon Dehesh, Justin W Walley, Jason A Corwin, Eva K F Chan, Daniel J. KliebensteinAbstract:Despite the described central role of jasmonate signaling in Plant Defense against necrotrophic pathogens, the existence of intraspecific variation in pathogen capacity to activate or evade Plant jasmonate-mediated Defenses is rarely considered. Experimental infection of jasmonate-deficient and jasmonate-insensitive Arabidopsis thaliana with diverse isolates of the necrotrophic fungal pathogen Botrytis cinerea revealed pathogen variation for virulence inhibition by jasmonate-mediated Plant Defenses and induction of Plant Defense metabolites. Comparison of the transcriptional effects of infection by two distinct B. cinerea isolates showed only minor differences in transcriptional responses of wild-type Plants, but notable isolate-specific transcript differences in jasmonate-insensitive Plants. These transcriptional differences suggest B. cinerea activation of Plant Defenses that require Plant jasmonate signaling for activity in response to only one of the two B. cinerea isolates tested. Thus, similar infection phenotypes observed in wild-type Plants result from different signaling interactions with the Plant that are likely integrated by jasmonate signaling.
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Distinct roles of jasmonates and aldehydes in Plant-Defense responses.
PloS one, 2008Co-Authors: E. Wassim Chehab, Daniel J. Kliebenstein, Roy Kaspi, Tatyana Savchenko, Heather C. Rowe, Florence Negre-zakharov, Katayoon DeheshAbstract:BackgroundMany inducible Plant-Defense responses are activated by jasmonates (JAs), C6-aldehydes, and their corresponding derivatives, produced by the two main competing branches of the oxylipin pathway, the allene oxide synthase (AOS) and hydroperoxide lyase (HPL) branches, respectively. In addition to competition for substrates, these branch-pathway-derived metabolites have substantial overlap in regulation of gene expression. Past experiments to define the role of C6-aldehydes in Plant Defense responses were biased towards the exogenous application of the synthetic metabolites or the use of genetic manipulation of HPL expression levels in Plant genotypes with intact ability to produce the competing AOS-derived metabolites. To uncouple the roles of the C6-aldehydes and jasmonates in mediating direct and indirect Plant-Defense responses, we generated Arabidopsis genotypes lacking either one or both of these metabolites. These genotypes were subsequently challenged with a phloem-feeding insect (aphids: Myzus persicae), an insect herbivore (leafminers: Liriomyza trifolii), and two different necrotrophic fungal pathogens (Botrytis cinerea and Alternaria brassicicola). We also characterized the volatiles emitted by these Plants upon aphid infestation or mechanical wounding and identified hexenyl acetate as the predominant compound in these volatile blends. Subsequently, we examined the signaling role of this compound in attracting the parasitoid wasp (Aphidius colemani), a natural enemy of aphids.Principal FindingsThis study conclusively establishes that jasmonates and C6-aldehydes play distinct roles in Plant Defense responses. The jasmonates are indispensable metabolites in mediating the activation of direct Plant-Defense responses, whereas the C6-aldehyes are not. On the other hand, hexenyl acetate, an acetylated C6-aldehyde, is the predominant wound-inducible volatile signal that mediates indirect Defense responses by directing tritrophic (Plant-herbivore-natural enemy) interactions.SignificanceThe data suggest that jasmonates and hexenyl acetate play distinct roles in mediating direct and indirect Plant-Defense responses. The potential advantage of this “division of labor” is to ensure the most effective Defense strategy that minimizes incurred damages at a reduced metabolic cost.
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Distinct roles of jasmonates and aldehydes in Plant-Defense responses.
PLoS ONE, 2008Co-Authors: E. Wassim Chehab, Daniel J. Kliebenstein, Roy Kaspi, Tatyana Savchenko, Heather C. Rowe, Florence Negre-zakharov, Katayoon DeheshAbstract:Author(s): Chehab, E Wassim; Kaspi, Roy; Savchenko, Tatyana; Rowe, Heather; Negre-Zakharov, Florence; Kliebenstein, Dan; Dehesh, Katayoon | Abstract: BACKGROUND: Many inducible Plant-Defense responses are activated by jasmonates (JAs), C(6)-aldehydes, and their corresponding derivatives, produced by the two main competing branches of the oxylipin pathway, the allene oxide synthase (AOS) and hydroperoxide lyase (HPL) branches, respectively. In addition to competition for substrates, these branch-pathway-derived metabolites have substantial overlap in regulation of gene expression. Past experiments to define the role of C(6)-aldehydes in Plant Defense responses were biased towards the exogenous application of the synthetic metabolites or the use of genetic manipulation of HPL expression levels in Plant genotypes with intact ability to produce the competing AOS-derived metabolites. To uncouple the roles of the C(6)-aldehydes and jasmonates in mediating direct and indirect Plant-Defense responses, we generated Arabidopsis genotypes lacking either one or both of these metabolites. These genotypes were subsequently challenged with a phloem-feeding insect (aphids: Myzus persicae), an insect herbivore (leafminers: Liriomyza trifolii), and two different necrotrophic fungal pathogens (Botrytis cinerea and Alternaria brassicicola). We also characterized the volatiles emitted by these Plants upon aphid infestation or mechanical wounding and identified hexenyl acetate as the predominant compound in these volatile blends. Subsequently, we examined the signaling role of this compound in attracting the parasitoid wasp (Aphidius colemani), a natural enemy of aphids. PRINCIPAL FINDINGS: This study conclusively establishes that jasmonates and C(6)-aldehydes play distinct roles in Plant Defense responses. The jasmonates are indispensable metabolites in mediating the activation of direct Plant-Defense responses, whereas the C(6)-aldehyes are not. On the other hand, hexenyl acetate, an acetylated C(6)-aldehyde, is the predominant wound-inducible volatile signal that mediates indirect Defense responses by directing tritrophic (Plant-herbivore-natural enemy) interactions. SIGNIFICANCE: The data suggest that jasmonates and hexenyl acetate play distinct roles in mediating direct and indirect Plant-Defense responses. The potential advantage of this "division of labor" is to ensure the most effective Defense strategy that minimizes incurred damages at a reduced metabolic cost.
Daniel F Klessig - One of the best experts on this subject based on the ideXlab platform.
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Functional analysis of Arabidopsis WRKY25 transcription factor in Plant Defense against Pseudomonas syringae
BMC Plant Biology, 2007Co-Authors: Zuyu Zheng, Daniel F Klessig, Baofang Fan, Stephen L Mosher, Zhixiang ChenAbstract:Background A common feature of Plant Defense responses is the transcriptional regulation of a large number of genes upon pathogen infection or treatment with pathogen elicitors. A large body of evidence suggests that Plant WRKY transcription factors are involved in Plant Defense including transcriptional regulation of Plant host genes in response to pathogen infection. However, there is only limited information about the roles of specific WRKY DNA-binding transcription factors in Plant Defense. Results We analyzed the role of the WRKY25 transcription factor from Arabidopsis in Plant Defense against the bacterial pathogen Pseudomonas syringae . WRKY25 protein recognizes the TTGACC W-box sequences and its translational fusion with green fluorescent protein is localized to the nucleus. WRKY25 expression is responsive to general environmental stress. Analysis of stress-induced WRKY25 in the Defense signaling mutants npr1 , sid2 , ein2 and coi1 further indicated that this gene is positively regulated by the salicylic acid (SA) signaling pathway and negatively regulated by the jasmonic acid signaling pathway. Two independent T-DNA insertion mutants for WRKY25 supported normal growth of a virulent strain of P. syringae but developed reduced disease symptoms after infection. By contrast, Arabidopsis constitutively overexpressing WRKY25 supported enhanced growth of P. syringae and displayed increased disease symptom severity as compared to wild-type Plants. These WRKY25 -overexpressing Plants also displayed reduced expression of the SA-regulated PR1 gene after the pathogen infection, despite normal levels of free SA. Conclusion The nuclear localization and sequence-specific DNA-binding activity support that WRKY25 functions as a transcription factor. Based on analysis of both T-DNA insertion mutants and transgenic overexpression lines, stress-induced WRKY25 functions as a negative regulator of SA-mediated Defense responses to P. syringae . This proposed role is consistent with the recent finding that WRKY25 is a substrate of Arabidopsis MAP kinase 4, a repressor of SA-dependent Defense responses.
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Functional analysis of Arabidopsis WRKY25 transcription factor in Plant Defense against Pseudomonas syringae
BMC plant biology, 2007Co-Authors: Zuyu Zheng, Daniel F Klessig, Stephen Mosher, Baofang Fan, Zhixiang ChenAbstract:Background A common feature of Plant Defense responses is the transcriptional regulation of a large number of genes upon pathogen infection or treatment with pathogen elicitors. A large body of evidence suggests that Plant WRKY transcription factors are involved in Plant Defense including transcriptional regulation of Plant host genes in response to pathogen infection. However, there is only limited information about the roles of specific WRKY DNA-binding transcription factors in Plant Defense.
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MAPK cascades in Plant Defense signaling
Trends in Plant Science, 2001Co-Authors: Shuqun Zhang, Daniel F KlessigAbstract:The Arabidopsis genome encodes ∼20 different mitogen-activated protein kinases (MAPKs) that are likely to be involved in growth, development and responses to endogenous and environmental cues. Several Plant MAPKs are activated by a variety of stress stimuli, including pathogen infection, wounding, temperature, drought, salinity, osmolarity, UV irradiation, ozone and reactive oxygen species. Recent gain-of-function studies show that two tobacco MAPKs induce the expression of Defense genes and cause cell death. By contrast, loss-of-function studies of other MAPK pathways revealed negative regulation of disease resistance. This 'push-and-pull' regulation by different MAPK pathways might provide a more precise control of Plant Defense responses.
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nitric oxide and salicylic acid signaling in Plant Defense
Proceedings of the National Academy of Sciences of the United States of America, 2000Co-Authors: Daniel F Klessig, Jyoti Shah, Shuqun Zhang, Jörg Durner, Rob Noad, Duroy A Navarre, David Wendehenne, Dhirendra Kumar, Jun Ma Zhou, Pradeep KachrooAbstract:Salicylic acid (SA) plays a critical signaling role in the activation of Plant Defense responses after pathogen attack. We have identified several potential components of the SA signaling pathway, including (i) the H2O2-scavenging enzymes catalase and ascorbate peroxidase, (ii) a high affinity SA-binding protein (SABP2), (iii) a SA-inducible protein kinase (SIPK), (iv) NPR1, an ankyrin repeat-containing protein that exhibits limited homology to IκBα and is required for SA signaling, and (v) members of the TGA/OBF family of bZIP transcription factors. These bZIP factors physically interact with NPR1 and bind the SA-responsive element in promoters of several Defense genes, such as the pathogenesis-related 1 gene (PR-1). Recent studies have demonstrated that nitric oxide (NO) is another signal that activates Defense responses after pathogen attack. NO has been shown to play a critical role in the activation of innate immune and inflammatory responses in animals. Increases in NO synthase (NOS)-like activity occurred in resistant but not susceptible tobacco after infection with tobacco mosaic virus. Here we demonstrate that this increase in activity participates in PR-1 gene induction. Two signaling molecules, cGMP and cyclic ADP ribose (cADPR), which function downstream of NO in animals, also appear to mediate Plant Defense gene activation (e.g., PR-1). Additionally, NO may activate PR-1 expression via an NO-dependent, cADPR-independent pathway. Several targets of NO in animals, including guanylate cyclase, aconitase, and mitogen-activated protein kinases (e.g., SIPK), are also modulated by NO in Plants. Thus, at least portions of NO signaling pathways appear to be shared between Plants and animals.
Zhixiang Chen - One of the best experts on this subject based on the ideXlab platform.
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Functional analysis of Arabidopsis WRKY25 transcription factor in Plant Defense against Pseudomonas syringae
BMC plant biology, 2007Co-Authors: Zuyu Zheng, Daniel F Klessig, Stephen Mosher, Baofang Fan, Zhixiang ChenAbstract:Background A common feature of Plant Defense responses is the transcriptional regulation of a large number of genes upon pathogen infection or treatment with pathogen elicitors. A large body of evidence suggests that Plant WRKY transcription factors are involved in Plant Defense including transcriptional regulation of Plant host genes in response to pathogen infection. However, there is only limited information about the roles of specific WRKY DNA-binding transcription factors in Plant Defense.
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Functional analysis of Arabidopsis WRKY25 transcription factor in Plant Defense against Pseudomonas syringae
BMC Plant Biology, 2007Co-Authors: Zuyu Zheng, Daniel F Klessig, Baofang Fan, Stephen L Mosher, Zhixiang ChenAbstract:Background A common feature of Plant Defense responses is the transcriptional regulation of a large number of genes upon pathogen infection or treatment with pathogen elicitors. A large body of evidence suggests that Plant WRKY transcription factors are involved in Plant Defense including transcriptional regulation of Plant host genes in response to pathogen infection. However, there is only limited information about the roles of specific WRKY DNA-binding transcription factors in Plant Defense. Results We analyzed the role of the WRKY25 transcription factor from Arabidopsis in Plant Defense against the bacterial pathogen Pseudomonas syringae . WRKY25 protein recognizes the TTGACC W-box sequences and its translational fusion with green fluorescent protein is localized to the nucleus. WRKY25 expression is responsive to general environmental stress. Analysis of stress-induced WRKY25 in the Defense signaling mutants npr1 , sid2 , ein2 and coi1 further indicated that this gene is positively regulated by the salicylic acid (SA) signaling pathway and negatively regulated by the jasmonic acid signaling pathway. Two independent T-DNA insertion mutants for WRKY25 supported normal growth of a virulent strain of P. syringae but developed reduced disease symptoms after infection. By contrast, Arabidopsis constitutively overexpressing WRKY25 supported enhanced growth of P. syringae and displayed increased disease symptom severity as compared to wild-type Plants. These WRKY25 -overexpressing Plants also displayed reduced expression of the SA-regulated PR1 gene after the pathogen infection, despite normal levels of free SA. Conclusion The nuclear localization and sequence-specific DNA-binding activity support that WRKY25 functions as a transcription factor. Based on analysis of both T-DNA insertion mutants and transgenic overexpression lines, stress-induced WRKY25 functions as a negative regulator of SA-mediated Defense responses to P. syringae . This proposed role is consistent with the recent finding that WRKY25 is a substrate of Arabidopsis MAP kinase 4, a repressor of SA-dependent Defense responses.
Jyoti Shah - One of the best experts on this subject based on the ideXlab platform.
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Lipases in Signaling Plant Defense Responses
Signaling and Communication in Plants, 2013Co-Authors: Jyoti ShahAbstract:Cellular membranes are important reservoirs for signaling lipids and their precursors. Plant lipases have important functions in the release/synthesis of signaling lipids that contribute to Plant Defense against pests, including effector- and MAMP-triggered immunity and the hypersensitive response. However, some pests have evolved a way to hijack host lipases and use them to counter and/or suppress host Defenses. Other pests actively secrete lipases to breakdown host membranes, releasing molecular signals that benefit growth and development of the pest. This chapter focuses on progress made in recent years toward the identification and characterization of lipases that have important roles in the outcome of Plant interaction with pests.
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The salicylic acid loop in Plant Defense
Current Opinion in Plant Biology, 2003Co-Authors: Jyoti ShahAbstract:Salicylic acid is an important signal molecule in Plant Defense. In the past two years, significant progress has been made in understanding the mechanism of salicylic-acid biosynthesis and signaling in Plants. A pathway similar to that found in some bacteria synthesizes salicylic acid from chorismate via isochorismate. Salicylic-acid signaling is mediated by at least two mechanisms, one requiring the NON-EXPRESSOR OF PR1 (NPR1) gene and a second that is independent of NPR1. Feedback loops involving salicylic acid modulate upstream signals. These feedback loops may provide a point for integrating developmental, environmental and other Defense-associated signals, and thus fine-tune the Defense responses of Plants.
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nitric oxide and salicylic acid signaling in Plant Defense
Proceedings of the National Academy of Sciences of the United States of America, 2000Co-Authors: Daniel F Klessig, Jyoti Shah, Shuqun Zhang, Jörg Durner, Rob Noad, Duroy A Navarre, David Wendehenne, Dhirendra Kumar, Jun Ma Zhou, Pradeep KachrooAbstract:Salicylic acid (SA) plays a critical signaling role in the activation of Plant Defense responses after pathogen attack. We have identified several potential components of the SA signaling pathway, including (i) the H2O2-scavenging enzymes catalase and ascorbate peroxidase, (ii) a high affinity SA-binding protein (SABP2), (iii) a SA-inducible protein kinase (SIPK), (iv) NPR1, an ankyrin repeat-containing protein that exhibits limited homology to IκBα and is required for SA signaling, and (v) members of the TGA/OBF family of bZIP transcription factors. These bZIP factors physically interact with NPR1 and bind the SA-responsive element in promoters of several Defense genes, such as the pathogenesis-related 1 gene (PR-1). Recent studies have demonstrated that nitric oxide (NO) is another signal that activates Defense responses after pathogen attack. NO has been shown to play a critical role in the activation of innate immune and inflammatory responses in animals. Increases in NO synthase (NOS)-like activity occurred in resistant but not susceptible tobacco after infection with tobacco mosaic virus. Here we demonstrate that this increase in activity participates in PR-1 gene induction. Two signaling molecules, cGMP and cyclic ADP ribose (cADPR), which function downstream of NO in animals, also appear to mediate Plant Defense gene activation (e.g., PR-1). Additionally, NO may activate PR-1 expression via an NO-dependent, cADPR-independent pathway. Several targets of NO in animals, including guanylate cyclase, aconitase, and mitogen-activated protein kinases (e.g., SIPK), are also modulated by NO in Plants. Thus, at least portions of NO signaling pathways appear to be shared between Plants and animals.
Zuyu Zheng - One of the best experts on this subject based on the ideXlab platform.
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Functional analysis of Arabidopsis WRKY25 transcription factor in Plant Defense against Pseudomonas syringae
BMC plant biology, 2007Co-Authors: Zuyu Zheng, Daniel F Klessig, Stephen Mosher, Baofang Fan, Zhixiang ChenAbstract:Background A common feature of Plant Defense responses is the transcriptional regulation of a large number of genes upon pathogen infection or treatment with pathogen elicitors. A large body of evidence suggests that Plant WRKY transcription factors are involved in Plant Defense including transcriptional regulation of Plant host genes in response to pathogen infection. However, there is only limited information about the roles of specific WRKY DNA-binding transcription factors in Plant Defense.
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Functional analysis of Arabidopsis WRKY25 transcription factor in Plant Defense against Pseudomonas syringae
BMC Plant Biology, 2007Co-Authors: Zuyu Zheng, Daniel F Klessig, Baofang Fan, Stephen L Mosher, Zhixiang ChenAbstract:Background A common feature of Plant Defense responses is the transcriptional regulation of a large number of genes upon pathogen infection or treatment with pathogen elicitors. A large body of evidence suggests that Plant WRKY transcription factors are involved in Plant Defense including transcriptional regulation of Plant host genes in response to pathogen infection. However, there is only limited information about the roles of specific WRKY DNA-binding transcription factors in Plant Defense. Results We analyzed the role of the WRKY25 transcription factor from Arabidopsis in Plant Defense against the bacterial pathogen Pseudomonas syringae . WRKY25 protein recognizes the TTGACC W-box sequences and its translational fusion with green fluorescent protein is localized to the nucleus. WRKY25 expression is responsive to general environmental stress. Analysis of stress-induced WRKY25 in the Defense signaling mutants npr1 , sid2 , ein2 and coi1 further indicated that this gene is positively regulated by the salicylic acid (SA) signaling pathway and negatively regulated by the jasmonic acid signaling pathway. Two independent T-DNA insertion mutants for WRKY25 supported normal growth of a virulent strain of P. syringae but developed reduced disease symptoms after infection. By contrast, Arabidopsis constitutively overexpressing WRKY25 supported enhanced growth of P. syringae and displayed increased disease symptom severity as compared to wild-type Plants. These WRKY25 -overexpressing Plants also displayed reduced expression of the SA-regulated PR1 gene after the pathogen infection, despite normal levels of free SA. Conclusion The nuclear localization and sequence-specific DNA-binding activity support that WRKY25 functions as a transcription factor. Based on analysis of both T-DNA insertion mutants and transgenic overexpression lines, stress-induced WRKY25 functions as a negative regulator of SA-mediated Defense responses to P. syringae . This proposed role is consistent with the recent finding that WRKY25 is a substrate of Arabidopsis MAP kinase 4, a repressor of SA-dependent Defense responses.
