Transcriptional control of plant immune-response genes by active DNA demethylation
T. HALTER (1), J. Wang (2), E. Lastrucci (2), D. Amesefe (2), R. Birkenbihl (3), I. Somssich (3), L. Navarro (2) (1) Institut de Biologie de l'Ecole Normale Supérieure (IBENS), France; (2) IBENS, France; (3) MPI Köln, Germany

DNA methylation is an epigenetic mark that silences transposable elements and repeats. In Arabidopsis, CG and CHG methylation marks are maintained by MET1 and CMT3 respectively, while CHH methylation is maintained by the RNA-directed DNA methylation (RdDM) pathway. Furthermore, the demethylase REPRESSOR OF SILENCING1 (ROS1) actively erases cytosine methylation in all sequence contexts. MET1 and RdDM components negatively regulate resistance against a virulent strain of Pseudomonas syringae, and accordingly, siRNAs and DNA methylation directly control several immune-response genes. By contrast, ROS1 positively regulates plant defense against this bacterium by demethylating promoters of some defense genes, thereby facilitating their transcriptional activation. However, the extent to which ROS1 controls the transcriptional status of defense genes at the whole genome level remains ill defined. Here, we have conducted whole-genome mRNA-, small RNA- and bisulfite-sequencing analyses in ros1 mutant and have retrieved the whole set of immune-response genes that are controlled by ROS1. Their regulation by ROS1 during elicitation and their functional relevance in antibacterial resistance will be presented. I will additionally present the mechanism by which ROS1 facilitates the transcriptional activation of these defense genes during elicitation and discuss the possible contribution of this regulatory mechanism to the adaptive plasticity of plants under pathogen constraints.

Abstract Number: P11-359
Session Type: Poster