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Abstract Detail


Plant Defense

Tsuchiya, Tokuji [1], Wei, Yu-Hung Linda [2], Eulgem, Thomas [3].

EDM2, a novel transcriptional regulator mediating disease resistance in Arabidopsis thaliana.

Plant disease resistance (R) genes mediate strong pathogen resistance. The R gene RPP7 confers resistance of Arabidopsis to the oomycete Hyaloperonospora parasitica. EDM2 (enhanced downy mildew 2) was identified in a mutant screen for loci required for RPP7 function and isolated by map-based cloning. EDM2 mutations are recessive, block an early defense signaling step, fully abolish RPP7-resistance, and reduce RPP7 transcript levels, strongly suggesting that EDM2 is a positive regulator of RPP7 expression. EDM2 is structurally unrelated to any known components of the plant immune system, bears typical features of transcriptional regulators, but does not belong to any previously characterized classes of transcription factors. Our main goal is to understand the molecular role of EDM2 in disease resistance and its connection to RPP7. We found that EDM2 is nuclear localized and activates transcription. By yeast two-hybrid screening we identified multiple chromatin associated proteins and transcriptional regulators that specifically interact with EDM2. Microarray and RT-PCR analysis revealed besides RPP7 several other R-like genes that are regulated by EDM2, suggesting it has additional roles in the plant immune system. By EMSAs we identified a binding site of EDM2 in the promoters of RPP7 and other putative EDM2 target genes. Mechanistic details of EDM2-dependent R gene activation, their connection to defense signaling and their significance for disease resistance are being examined. EDM2 appears to be the first transcription factor implicated in controlling R gene activity. We propose that this novel regulator mediates disease resistance by fine-tuning the transcription of RPP7 and additional R genes.


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1 - Univesity of California - Riveside, Center for Plant Cell Biology, Department of Botany and Plant Sciences
2 - University of California - Riverside, Center for Plant Cell Biology, Department of Botany and Plant Sciences
3 - University of California - Riverside, Center for Plant Cell Biology, Department of Botany and Plant Sciences, 3214 Batchelor Hall, Riverside, CA, 92521, USA

Keywords:
disease resistance protein
transcription factor.

Presentation Type: ASPB Minisymposium
Session: M09
Location: Continental A/Hilton
Date: Monday, July 9th, 2007
Time: 8:55 AM
Number: M09002
Abstract ID:641


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