CeBiTec Colloquium
| date |
Monday, March 4th 2013, 17 c.t. |
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| location |
G2-104, CeBiTec Building |
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| speaker |
Dr. Thomas EulgemCenter for Plant Cell Biology, Institute for Integrative Genome Biology, Department of Botany and Plant Sciences, University of California-Riverside, USA |
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| title |
EDM2, an Epigenetic Regulator of Transposon Activity Controlling Innate Immunity & Development in Arabidopsis |
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| abstract | The Arabidopsis thaliana gene EDM2 is required for race-specific immunity and several developmental processes, such as floral transition and leaf pavement cell formation. It encodes a nuclear protein with features of epigenetic regulators, including a novel PHD finger-like chromatin docking domain, and interacts with EMSY-type chromatin remodeling factors. EDM2 positively affects steady-state transcript levels of the disease resistance (R)-gene RPP7 and represses those of the floral suppressor FLC. Both EDM2 and RPP7 are required for race-specific immunity of Arabidopsis against the pathogenic oomycete Hyaloperonospora arabidopsidis. We found EDM2 to affect transcriptional silencing of several transposons by modulating their levels of dimethylated lysine 9 of histone H3 (H3K9me2) and 5-methyl cytosine at CHG motifs (5mCHG; H=T, A or C). Consistent with a role in transposon silencing, EDM2 affects RPP7 expression and innate immunity by elevating levels of these two suppressive epigenetic marks at the COPIA88 retrotransposon in the 1st intron of RPP7. By controlling H3K9me2 and 5mCHG levels at RPP7/COPIA88, EDM2 affects the RPP7 transcript splice pattern and the balance between non-coding and RPP7-coding transcripts, which seems critical for RPP7-mediated immunity. This study links epigenetic chromatin marks to race-specific plant immunity and uncovers mechanistic effects of a transposon on the expression of a nearby gene. R-genes often occur in clusters. As many R-gene clusters harbor transposons, understanding of chromatin-related effects of EDM2 at the RPP7/COPIA88 locus can serve as a paradigm for the fine tuning of R-gene expression and roles of transposons in the evolution of R-gene function. Literature: Eulgem, et al. (2007). EDM2 is required for RPP7-dependent disease resistance in Arabidopsis and affects RPP7 transcript levels. The Plant Journal 49: 829-839. Tsuchiya, and Eulgem (2010). The Arabidopsis defense component EDM2 affects the floral transition in an FLC-dependent manner. The Plant Journal 62: 518-28. Tsuchiya, and Eulgem (2010). Co-option of EDM2 to distinct regulatory modules in Arabidopsis thaliana development. BMC Plant Biology. 10: 203. Tsuchiya, and Eulgem (2011). EMSY-like genes are required for full RPP7-mediated race-specific immunity and basal defense in Arabidopsis. Molecular Plant Microbe Interactions 24: 1573-1581. |
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| host |
Prof. Dr. Bernd Weisshaar |