Dynamic differential methylation facilitates pathogen stress response in Arabidopsis.

I n plants, DNA methylation plays important roles in silencing transposable elements (TEs) and endogenous genes. Several elegant examples of dynamic changes in DNA methylation during gamete or seed development have been recently described in Arabidopsis (1, 2). A considerable number of cell-to-cell variations in methylation have also been detected in vegetative tissues (3, 4); however, whether differential methylation during vegetative development is a regulated process with any biological function remained unknown. In PNAS, Dowen et al. (5) describe the finding that pathogen attacks result in dynamic changes in DNA methylation, which in turn lead to the transcriptional activation of defense-related genes and elevated resistance against pathogens.