Interplay between MAMPs-triggered and SA-mediated defense responses
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ABSTRACT: The Arabidopsis Pathoarray 464_001 (GPL3638) was used to compare response of Col-0, pad4-1 (Zhou et al., 1998; Jirage et al., 1999) and sid2-2 (Wildermuth et al., 2001) to Pseudomonas syringae pv. tomato DC3000 hrcC mutant. SA production is drastically reduced in sid2 mutants. PAD4 is required for SA-mediated responses. The results suggested that the SA increase triggered by MAMPs is one major component in the MAMPs-triggered signaling mechanism. Keywords: Responses of Arabidopsis to Pseudomonas syringae pv. tomato DC3000 hrcC mutant
Project description:Expression profiling of wild-type plants and mutants with defects in key components of the defense signaling network was used to model the Arabidopsis network 24 hours after infection by Pseudomonas syringae pv. maculicola strain Psm ES4326. Results using the Affymetrix ATH1 array revealed that expression levels of most pathogen-responsive genes were affected by mutations in coi1, ein2, npr1, pad4, or sid2. These five mutations defined a small number of different expression patterns displayed by the majority of pathogen-responsive genes. P. syringae pv. tomato strain Pst DC3000 elicited a much weaker salicylic acid response than Psm ES4326. Additional mutants were profiled using a custom array. Profiles of pbs3 and ndr1 revealed major effects of these mutations and allowed PBS3 and NDR1 to be placed between the EDS1/PAD4 node and the SA synthesis node in the defense network. Comparison of coi1, dde2, and jar1 profiles showed that many genes were affected by coi1, but very few were affected by dde2 or jar1. Profiles of coi1 plants infected with Psm ES4326 were very similar to those of wild-type plants infected with bacteria unable to produce the phytotoxin coronatine, indicating that essentially all COI1-dependent gene expression changes in this system are caused by coronatine. This experiment consists of three biological replicates. For each genotype, two leaves per plant were pooled from three pots to prepare total RNA.
Project description:Expression profiling of wild-type plants and mutants with defects in key components of the defense signaling network was used to model the Arabidopsis network 24 hours after infection by Pseudomonas syringae pv. maculicola strain Psm ES4326. Results using the Affymetrix ATH1 array revealed that expression levels of most pathogen-responsive genes were affected by mutations in coi1, ein2, npr1, pad4, or sid2. These five mutations defined a small number of different expression patterns displayed by the majority of pathogen-responsive genes. P. syringae pv. tomato strain Pst DC3000 elicited a much weaker salicylic acid response than Psm ES4326. Additional mutants were profiled using a custom array. Profiles of pbs3 and ndr1 revealed major effects of these mutations and allowed PBS3 and NDR1 to be placed between the EDS1/PAD4 node and the SA synthesis node in the defense network. Comparison of coi1, dde2, and jar1 profiles showed that many genes were affected by coi1, but very few were affected by dde2 or jar1. Profiles of coi1 plants infected with Psm ES4326 were very similar to those of wild-type plants infected with bacteria unable to produce the phytotoxin coronatine, indicating that essentially all COI1-dependent gene expression changes in this system are caused by coronatine.
Project description:Salicylic acid (SA)-induced defense responses are important factors during effector triggered immunity and microbe-associated molecular pattern (MAMP)-induced immunity in plants. This article presents evidence that a member of the Arabidopsis CBP60 gene family, CBP60g, contributes to MAMP-triggered SA accumulation. CBP60g is inducible by both pathogen and MAMP treatments. Pseudomonas syringae growth is enhanced in cbp60g mutants. Expression profiles of a cbp60g mutant after MAMP treatment are similar to those of sid2 and pad4, suggesting a defect in SA signaling. Accordingly, cbp60g mutants accumulate less SA when treated with the MAMP flg22 or a P. syringae hrcC strain that activates MAMP signaling. MAMP-induced production of reactive oxygen species and callose deposition are unaffected in cbp60g mutants. CBP60g is a calmodulin-binding protein with a calmodulin-binding domain located near the N-terminus. Calmodulin binding is dependent on Ca2+. Mutations in CBP60g that abolish calmodulin binding prevent complementation of the SA production and bacterial growth defects of cbp60g mutants, indicating that calmodulin binding is essential for the function of CBP60g in defense signaling. These studies show that CBP60g constitutes a calmodulin-dependent link between MAMP recognition and SA accumulation that is important for resistance to P. syringae. This experiment consists of three biological replicates. For each genotype, two leaves per plant were pooled from three pots to prepare total RNA.
Project description:Salicylic acid (SA)-induced defense responses are important factors during effector triggered immunity and microbe-associated molecular pattern (MAMP)-induced immunity in plants. This article presents evidence that a member of the Arabidopsis CBP60 gene family, CBP60g, contributes to MAMP-triggered SA accumulation. CBP60g is inducible by both pathogen and MAMP treatments. Pseudomonas syringae growth is enhanced in cbp60g mutants. Expression profiles of a cbp60g mutant after MAMP treatment are similar to those of sid2 and pad4, suggesting a defect in SA signaling. Accordingly, cbp60g mutants accumulate less SA when treated with the MAMP flg22 or a P. syringae hrcC strain that activates MAMP signaling. MAMP-induced production of reactive oxygen species and callose deposition are unaffected in cbp60g mutants. CBP60g is a calmodulin-binding protein with a calmodulin-binding domain located near the N-terminus. Calmodulin binding is dependent on Ca2+. Mutations in CBP60g that abolish calmodulin binding prevent complementation of the SA production and bacterial growth defects of cbp60g mutants, indicating that calmodulin binding is essential for the function of CBP60g in defense signaling. These studies show that CBP60g constitutes a calmodulin-dependent link between MAMP recognition and SA accumulation that is important for resistance to P. syringae.
Project description:Pathogens target phytohormone signalling pathways to promote disease. Plants deploy salicylic acid (SA) mediated defences against biotrophs. Pathogens antagonise SA immunity by activating jasmonate signalling, e.g. Pseudomonas syringae pv. tomato DC3000 produces coronatine (COR), a jasmonate (JA) mimic. This study found unexpected dynamics between SA, JA and COR and co-operation between JAZ jasmonate repressor proteins during DC3000 infection. JA did not accumulate until late in the infection process and was higher in leaves challenged with coronatine deficient P. syringae or in the more resistant JA receptor mutant coi1. JAZ regulation was complex and coronatine alone was insufficient to sustainably induce JAZs. RNA was extracted from leaves of wild type Col-0 or the jaz5/10 mutant plants from leaves 6, 8, 12 or 16 hours after challenged with Pseudomonas syringae pv. tomato DC3000.
Project description:Pathogens target phytohormone signalling pathways to promote disease. Plants deploy salicylic acid (SA) mediated defences against biotrophs. Pathogens antagonise SA immunity by activating jasmonate signalling, e.g. Pseudomonas syringae pv. tomato DC3000 produces coronatine (COR), a jasmonate (JA) mimic. This study found unexpected dynamics between SA, JA and COR and co-operation between JAZ jasmonate repressor proteins during DC3000 infection. JA did not accumulate until late in the infection process and was higher in leaves challenged with coronatine deficient P. syringae or in the more resistant JA receptor mutant coi1. JAZ regulation was complex and coronatine alone was insufficient to sustainably induce JAZs.
Project description:To prevent activation of plant innate immunity the oomycete pathogen Hyaloperonospora arabidopsidis translocates effector proteins into infected cells of its host Arabidopsis thaliana. We noticed that some H. arabidopsidis effectors, when over-expressed in A. thaliana, render the plant more susceptible to infection by biotrophic pathogens (Fabro et al., 2011, PubMed PMID: 22072967). Here we performed transcriptome profiling of a representative transgenic line constitutively expressing H. arabidopsidis effector HaRxL106. We compared the transcriptomes of A. thaliana wild-type (Col-0) plants and an isogenic line expressing HaRxL106 before pathogen challenge and 24 h after infection with the compatible bacterial pathogen Pseudomonas syringae pv. tomato strain DC3000. HaRxL106 interacts with several Arabidopsis proteins (Mukhtar et al., 2011, PubMed PMID: 21798943; Wirthmueller et al., 2015, PubMed PMID: 25284001). To test whether the HaRxL106-interacting A. thaliana proteins MODIFIER OF SNC1, 6 (MOS6), 6B-INTERACTING PROTEIN 1-LIKE 1 (ASIL1) or RADICAL-INDUCED CELL DEATH1 (RCD1) are altered in their transcriptional response to a biotrophic pathogen we performed transcriptome profiling of mos6-1, asil1-1 and rcd1-1 mutants before and 24 h after infection with P. syringae pv. tomato DC3000.
Project description:To understand role of SALT- AND DROUGHT-INDUCED REALLY INTERESTING NEW GENE FINGER1 Gene (SDIR1). The expression profiling studies of SDIR1 overexpression plants and sdir1 mutants infected with P. syringae pv. tomato (DC3000) in comparison with wild-type control plants was conducted for plants three weeks after germination. Transcriptome data show that SDIR1 plays key role in suppression of salicylic acid (SA) mediated defense to cause susceptibility against biotrophic or hemi-biotrphic pathogens and resistance against necrotrophic pathogens.
Project description:Transcription profiling of Nicotinan benthamiana in response to Pectobacterium carotovorum WPP14 and Pseudomonas syringae pv. tomato DC3000
Project description:Background: Plants attenuate their responses to a variety of bacterial and fungal pathogens, leading to higher incidences of pathogen infection at night. However, little is known about the molecular mechanism responsible for the light-induced defence response; transcriptome data would likely facilitate the elucidation of this mechanism. Results: In this study, we observed diurnal changes in tomato resistance to Pseudomonas syringae pv. tomato DC3000 (Pto DC3000), with the greatest susceptibility before midnight. Nightly light treatment, particularly red light treatment, significantly enhanced the resistance; this effect was correlated with increased salicylic acid (SA) accumulation and defence-related gene transcription. RNA-seq analysis revealed that red light induced a set of circadian rhythm-related genes involved in the phytochrome and SA-regulated resistance response. The biosynthesis and signalling pathways of multiple plant hormones (auxin, SA, jasmonate, and ethylene) were co-ordinately regulated following Pto DC3000 infection and red light, and the SA pathway was most significantly affected by red light and Pto DC3000 infection. This result indicates that SA-mediated signalling pathways are involved in red light-induced resistance to pathogens. Importantly, silencing of nonexpressor of pathogensis-related genes 1 (NPR1) partially compromised red light-induced resistance against Pto DC3000. Furthermore, sets of genes involved in redox homeostasis (respiratory burst oxidase homologue, RBOH; glutathione S-transferases, GSTs; glycosyltransferase, GTs), calcium (calmodulin, CAM; calmodulin-binding protein, CBP), and defence (polyphenol oxidase, PPO; nudix hydrolase1, NUDX1) as well as transcription factors (WRKY18, WRKY53, WRKY60, WRKY70) and cellulose synthase were differentially induced at the transcriptional level by red light in response to pathogen challenge. Conclusions: Taken together, our results suggest that there is a diurnal change in susceptibility to Pto DC3000 with greatest susceptibility in the evening. The red light induced-resistance to Pto DC3000 at night is associated with enhancement of the SA pathway, cellulose synthase, and reduced redox homeostasis.