Expression analysis of Arabidopsis mpk11 mutant treated with flg22
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ABSTRACT: Arabidopsis MPK11 is activated and plays a role in the flg22 sensing. Mitogen-activated protein kinases (MAPKs) mediate cellular signal transduction during stress responses, as well as diverse growth and developmental steps in eukaryotes. Pathogen infection or treatment with conserved pathogen-associated molecular patterns (PAMPs) such as the bacterial flagellin-derived flg22 peptide are known to activate three Arabidopsis thaliana MAPKs, MPK3, MPK4 and MPK6. Several stresses, including flg22 treatment, are known to increase MPK11 expression but activation of MPK11 has not been shown. Here, we show that MPK11 activity can indeed be increased through flg22 elicitation. Expression profiling using a small-scale microarray for defense-related genes revealed that cinnamyl alcohol dehyrogenase 5 (CAD5) requires MPK11 for full flg22-induced expression. An mpk11 mutant showed increased flg22-mediated growth inhibition but no altered susceptibility to Pseudomonas syringae, Botrytis cinerea or Alternaria brassicicola.
Project description:Arabidopsis MPK11 is activated and plays a role in the flg22 sensing. Mitogen-activated protein kinases (MAPKs) mediate cellular signal transduction during stress responses, as well as diverse growth and developmental steps in eukaryotes. Pathogen infection or treatment with conserved pathogen-associated molecular patterns (PAMPs) such as the bacterial flagellin-derived flg22 peptide are known to activate three Arabidopsis thaliana MAPKs, MPK3, MPK4 and MPK6. Several stresses, including flg22 treatment, are known to increase MPK11 expression but activation of MPK11 has not been shown. Here, we show that MPK11 activity can indeed be increased through flg22 elicitation. Expression profiling using a small-scale microarray for defense-related genes revealed that cinnamyl alcohol dehyrogenase 5 (CAD5) requires MPK11 for full flg22-induced expression. An mpk11 mutant showed increased flg22-mediated growth inhibition but no altered susceptibility to Pseudomonas syringae, Botrytis cinerea or Alternaria brassicicola. A 24 DNA microarray study using toral RNA from an Arabidopsis mutant (mpk11 SALK049352) as well as wild type treated with water or flg22.
Project description:inra12-05_mut_flg_ii-FLG-MPKs ra12-05_mut_flg_ii - inra12-05_mut_flg_ii - Analysis of flg22-induced transcriptional changes in mpk3, mpk4 and mpk6 mutants. - 2 weeks old seedlings compared for transcriptome after a 30min mock or 1µM flg22 treatment.
Project description:inra12-05_mut_flg_ii-FLG-MPKs ra12-05_mut_flg_ii - inra12-05_mut_flg_ii - Analysis of flg22-induced transcriptional changes in mpk3, mpk4 and mpk6 mutants. - 2 weeks old seedlings compared for transcriptome after a 30min mock or 1µM flg22 treatment. 21 dye-swap - gene knock out,normal vs mutant comparison,treated vs untreated comparison
Project description:Alternative splicing (AS) of pre-mRNAs in plants is an important mechanism of gene regulation in environmental stress tolerance but plant signals involved are essentially unknown. Pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) is mediated by mitogen-activated protein kinases and the majority of PTI defense genes are regulated by MPK3, MPK4 and MPK6. These responses have been mainly analyzed at the transcriptional level, however many splicing factors are direct targets of MAPKs. Here, we studied alternative splicing induced by the PAMP flagellin in Arabidopsis.
Project description:In Arabidopsis, mitogen-activated protein kinases MPK3, MPK4 and MPK6 constitute essential relays for a variety of functions including cell division, development and innate immunity. While some substrates of MPK3, MPK4 and MPK6 have been identified, the picture is still far from complete. To identify substrates of these MAPKs in cell division, growth and development we compared the phosphoproteomes of wild-type and mpk3, mpk4 and mpk6. To study the function of these MAPKs in innate immunity, we analyzed their phosphoproteomes following activation by a microbe-associated molecular pattern (MAMP). Partially overlapping substrates were retrieved for all three MAPKs, showing target specificity to one, two or all three MAPKs in different biological processes. More precisely, our results illustrate the fact that the entity to be defined as a specific or a shared substrate for MAPKs is not a phosphoprotein but a particular (S/T)P phosphorylation site in a given protein. As a whole, 152 peptides were identified to be differentially phosphorylated in response to MAMP treatment and/or when compared between genotypes and 70 of them could be classified as putative MAPK targets. Biochemical analysis of a number of putative MAPK substrates by phosphorylation and interaction assays confirmed the global phosphoproteome approach. Our study finally expands the set of MAPK substrates to involve other protein kinases, including calcium-dependent (CDPK) and sugar non-fermenting (SnRK) protein kinases.
Project description:Despite their importance, plant MAP kinase targets are still poorly elucidated. Here, the specific in vivo interaction of an ethylene response factor (ERF104) with the Arabidopsis MAP kinase, MPK6, is shown by fluorescence resonance energy transfer. The interaction, which is lost within minutes after treatment with the flagellin-derived flg22 peptide, is dependent on both MPK6 kinase activity and rapid ethylene signaling initiated downstream of MPK6 activation. ERF104 is an MPK6 substrate and phosphorylation site mutations affected its stability. ERF104 activates promoters with GCC elements. This was evident from microarray data of overexpressing transgenic plants, where promoters of up regulated genes contain GCC motifs and chromatin immunoprecipitation showing ERF104 association with PDF1.2 promoter. The ERF104 overexpressor did not affect biotrophic bacteria proliferation but was more susceptible to necrotrophic Botrytis cinerea. Microarray performed with erf104 or mpk6 revealed only a limited number of flg22-induced genes that require these elements - possibly as a result of functional redundancies. Thus, ERF104 phosphorylation by MPK6, in concert with ethylene signaling induced by pathogen-derived molecules, modulates defense in Arabidopsis.
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:SmD3 is a core protein of small nuclear ribonucleoproteins essential for pre-mRNA splicing. To assess the role of Arabidopsis SmD3-b in response to biotic stress we investigated sensitivity of the smd3-b mutant to Pseudomonas syringae pv. tomato DC3000 infection and its pathogenesis effectors flg22, elf18 and coronatine. We show that the mutant exhibits enhanced susceptibility to Pst accompanied with marked changes in the expression of key pathogenesis markers. mRNA levels of major biotic stress response factors were also altered upon treatment with Pseudomonas effectors. Our genome-wide transcriptome analysis of smd3-b mutant infected with Pst confirmed that lack of SmD3 protein deregulates defense to Pst DC3000 infection on the transcriptional level, including defects in splicing and altered pattern of alternative splicing. In addition, callose deposition, which is another marker of plant immunity, was strongly induced by elf18 and flg22 in the mutant, whereas production of reactive oxygen species triggered by flg22 was reduced. Finally, detection of phosphorylated forms of MPK3, MPK6 and MPK4/11 revealed higher activation of all MAPKs in the smd3-b mutant. All our data indicate that SmD3 contributes to plant immune response possibly via regulation of mRNA splicing of the key pathogenesis factors.