Control of Chloroplast Development by Active DNA demethylation

Abstract

In plants, RNA-dependent DNA methylation (RdDM) establishes de novo DNA methylation, whereas DNA demethylases remove established DNA methylation. Despite of significant effect of these pathways on the DNA methylation, only a few biological processes have been associated with DNA methylation. Here we performed a forward genetic screen in Arabidopsis for suppressors of chloroplast Clp protease mutant clpt. We identified SUPPRESSOR OF CLPT1 (SOCT1) encoding IDM3, SOCT2 encoding NRPD1, SOCT3/4 encoding RDR2. T-DNA mutants of ROS1 and IDM3 interacting partners suppressed clpt, which was mediated by DNA hypermethylation. Also, suppression of clpt by soct2/3/4 was associated reduced ROS1 activity in the mutants. In addition, we also found that chloroplast developmental defect of clpt induces DNA methylation at RdDM target sites. Together, we revealed that chloroplast development can be regulated by DNA demethylation. Also, we suggest that DNA methylation as a stress response for adjusting chloroplast developmental stresses.