Project description:Plant microRNAs (miRNAs) have been implicated in plant immunity. These mainly focusing Arabidopsis thaliana threatened by (hemi-)biotrophic pathogens such as the bacterial pathogen Pseudomonas syringae. Here, we show that the Arabidopsis miRNA pathway is important for defense responses against the necrotrophic fungus Alternaria brassicicola. The miRNA pathway mutant ago1 exhibits an exaggerated response when treated with A. brassicicola, proposing that AGO1 is positive regulator. We found a subset of Arabidopsis miRNAs that quickly change their expression and their abundance in AGO1 complexes in plants exposed to A. brassicicola. The miRNAs responding to pathogen treatment are mainly targeting genes encoding metabolic enzymes, proteins involved protein degradation or transposons. In case of miR163, A. brassicicola infection results in increased levels of miRNA precursors and preferential accumulation of an unspliced form of pri-miR163, suggesting that A. brassicicola infection changes the transcriptional and post-regulation of pri-miRNAs. miR163 acts as a negative regulator of plant defense because mir163 mutants are more resistant when treated with A. brassicicola. Taken together, our results reveal the existence of positively and negatively acting Arabidopsis miRNA modulating the defense responses against A. brassicicola and highlight the importance of host miRNAs in the interaction between plants and necrotrophic pathogens.
Project description:Plant microRNAs (miRNAs) have been implicated in plant immunity. These mainly focusing Arabidopsis thaliana threatened by (hemi-)biotrophic pathogens such as the bacterial pathogen Pseudomonas syringae. Here, we show that the Arabidopsis miRNA pathway is important for defense responses against the necrotrophic fungus Alternaria brassicicola. The miRNA pathway mutant ago1 exhibits an exaggerated response when treated with A. brassicicola, proposing that AGO1 is positive regulator. We found a subset of Arabidopsis miRNAs that quickly change their expression and their abundance in AGO1 complexes in plants exposed to A. brassicicola. The miRNAs responding to pathogen treatment are mainly targeting genes encoding metabolic enzymes, proteins involved protein degradation or transposons. In case of miR163, A. brassicicola infection results in increased levels of miRNA precursors and preferential accumulation of an unspliced form of pri-miR163, suggesting that A. brassicicola infection changes the transcriptional and post-regulation of pri-miRNAs. miR163 acts as a negative regulator of plant defense because mir163 mutants are more resistant when treated with A. brassicicola. Taken together, our results reveal the existence of positively and negatively acting Arabidopsis miRNA modulating the defense responses against A. brassicicola and highlight the importance of host miRNAs in the interaction between plants and necrotrophic pathogens.
Project description:A major part of plant immune response is mediated by signaling pathways controlled by three hormnes, jasmonate, ethylene, and salicylate. The involvement of each of these hormone signaling pathways in Arabidopsis thaliana was investigated in response to infection of a necrotrophic fungal pathogen, A. brassicicola. Arabideopsis mutants deficient in these hormone signaling pathways were compared to wild type.
Project description:Gibberellin (GA) promotes plant growth by destabilizing DELLA proteins. DELLA proteins integrate multiple hormonal and environmental stress responses. We investigated the role of GA and DELLA proteins in plant defence. We used microarrays to detail the global programme of gene expression controlled by DELLA proteins and identified distinct classes of differentially regulated genes in response to pathogens, hormones or pathogen elicitors. Experiment Overall Design: Five weeks old short day grown Arabidopsis leaf discs were used to treat with flg22 and samples were collected after 1 hour and 2 hour time points. For Alternaria brassicicola, five weeks old plants were drop inoculated with 4x 5µl droplets of Alternaria brassicicola spores (5x105 spores/ml) and samples were collected 3 days post inoculation. Five weeks old plants were infiltrated with Pst DC3000 (2x105cfu/ml) bacteria and samples were collected after 12 hours post infiltration. For methyl jasmonate treatments, five weeks old plants were sprayed with 10µM Methyl Jasmonate solution, covered with plastic bags and samples were collected after one hour.
Project description:The mkkkC5 mutant, a knockout line of MAPKKKC5, shows changes in growth and development, as well as an altered Alternaria sensitivity. It was shown by Brader and Djamei et al.(2007) that Alternaria brassicicola sensitivity is also influenced by MKK2-activity. Aim of this experiment is to access the transcriptional changes in the mkkkc5plants as well as in plants overexpressing a constitutively active MKK2-version (MKK2EE). The second part of the experiment addresses transcriptional changes in these plants after Alternaria brassicicola infection. au07-09_alternaria Keywords: treatment variations Alternaria brassicicola infection of 25 day old mkkkc5- , pGreen::MKK2EE-myc and WT Col-0 plants. Sampling after 0, 1 and 2 days. Comparison between mutants and WT at corresponding timepoints. Additionally comparison between WT-samples at different timepoints. 16 dye-swap - CATMA arrays