Project description: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:The plant innate immunity consists of the two interconnected mechanisms, pattern-triggered immunity (PTI) and effector-triggered immunity (ETI). Although much is known about how plants trigger immune responses upon pathogen recognition, the genetic program by which plants avoid an overshoot in pathogen-triggered immune responses remains largely unknown. Here, we discovered a trihelix transcription factor, GT-3a, as an immune-inducible negative regulator of bacterial resistance in Arabidopsis thaliana. Analysis of public RNA-seq data revealed that GT-3a is specifically induced by ETI activation not by PTI activation. Overexpression of GT-3a suppressed resistance against the bacterial pathogen Pseudomonas syringae pv. tomato DC3000 (Pto) and Pto-elicited expression of salicylic acid (SA)-responsive genes. Our results suggest that transcriptional induction of GT-3a circumvents the overshooting of SA-mediated defense responses during ETI.
Project description:Wounding is a trigger for both regeneration and defense in plants, but it is not clear if the two responses are linked by common activation or represent potential tradeoffs. While plant glutamate-like receptors (GLRs) are known to mediate defense responses, we implicate GLRs in regeneration through dynamic changes in chromatin and transcription in reprogramming cells near wound sites. Here, we show that genetic mutation and pharmacological inhibition of GLRs increases regeneration efficiency in multiple organ repair systems and plant species. Perturbation of GLR-mediated function, possibly by affecting Calcium fluxes, speeds cell division and re-specification of the stem cell niche while dampening a subset of defense responses. We show that the GLRs work through salicylic acid (SA) signaling in their effects on regeneration, with mutants in the SA receptor NPR1 partially resistant to GLR perturbation and hyper regenerative. These findings reveal a conserved mechanism that regulates a tradeoff between defense and regeneration and also offer new strategies to improve regeneration in agricultural and conservation.
Project description:Low R:FR signaling through phytochromes induces shade avoidance responses, including petiole elongation. Salicylic acid-mediated defense against pathogens is inhibited under these conditions. Using microarrays we studied the crosstalk between low R:FR and SA at the global gene expression level in Arabidopsis thaliana.
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:Agrobacterium tumefaciens is a special plant pathogen causing crown gall disease. This pathogen is well known for the technology Agrobacterium-mediated transformation. As a pathogen, Agrobacterium triggers plant immunity, and this affects transformation. But the signaling components and pathways in plant immunity to Agrobacterium remain elusive. We demonstrate two Arabidopsis MAPKKs MKK4/MKK5 and their downstream MAPKs MPK3/MPK6 play a major role in both Agrobacterium-triggered immunity and Agrobacterium-mediated transformation. Agrobacteria induce MPK3/MPK6 activity and plant defense responsive genes expression in a very early stage. This process is dependent on MKK4/MKK5 function. Loss of function of MKK4 and MKK5 or their downstream MPK3 and MPK6 abolishes plant immunity to agrobacteria, and increases the transformation frequency, while activation of MKK4 and MKK5 enhances the plant immunity and represses the transformation. Global transcriptome indicates agrobacteria induce various plant defense pathways, including ROS production, ethylene and SA-mediated defense responses, and MKK4/MKK5 is essential for these pathways induction. Activation of MKK4 and MKK5 promotes ROS production and cell death in agrobacteria infection process. Ethylene and SA act bypass of MKK4/MKK5 signaling to regulate transformation. Based on these results, we propose MKK4/5-MPK3/6 cascade is an essential signaling pathway to regulate Agrobacterium-mediated transformation by modulating Agrobacterium-triggered plant immunity.
Project description:Low R:FR signaling through phytochromes induces shade avoidance responses, including petiole elongation. Salicylic acid-mediated defense against pathogens is inhibited under these conditions. Using microarrays we studied the crosstalk between low R:FR and SA at the global gene expression level in Arabidopsis thaliana. Plants were exposed for 2 h. to the following treatments: high R/FR with mock spray, low R/FR with mock spray, high R/FR with SA spray, low R/FR with SA spray. Gene expression was determined in petioles.
Project description:Wounding is a trigger for both regeneration and defense in plants, but it is not clear if the two responses are linked by common activation or represent potential tradeoffs. While plant glutamate-like receptors (GLRs) are known to mediate defense responses, we implicate GLRs in regeneration through dynamic changes in chromatin and transcription in reprogramming cells near wound sites. Here, we show that genetic mutation and pharmacological inhibition of GLRs increases regeneration efficiency in multiple organ repair systems and plant species. Perturbation of GLR-mediated function, possibly by affecting Calcium fluxes, speeds cell division and re-specification of the stem cell niche while dampening a subset of defense responses. We show that the GLRs work through salicylic acid (SA) signaling in their effects on regeneration, with mutants in the SA receptor NPR1 partially resistant to GLR perturbation and hyper regenerative. These findings reveal a conserved mechanism that regulates a tradeoff between defense and regeneration and also offer new strategies to improve regeneration in agricultural and conservation.
Project description:DCA (3,5-Dichloroanthranilic acid) is a newly identified synthetic defense elicitor. To perform a comparative analysis of defense responses triggered by DCA and the structurally related defense inducer INA (2,6-Dichloroisonicotinic acid) Affymetrix chip experiments were performed with Arabidopsis thaliana seedlings treated with one of these two compounds.