Abstract

DNA methylation maintains genome stability and regulates gene expression. In mammals, DNA methylation is reprogrammed in the germ line from one generation to the next. In plants, it was considered that patterns of DNA methylation are stably maintained through sexual reproduction. However we now provide evidence that indicate that DNA methylation is reprogrammed during gametogenesis and embryogenesis. Arabidopsis gametogenesis is marked by reduction of DNA methylation activity. After fertilization both maintenance and de novo DNA methyltransferases are expressed strongly in the embryo leading to reestablishment of DNA methylation patterns on transposable element and acquisition of new patterns of DNA methylation. We propose that this cycle of DNA methylation enables a limited degree of reprogramming of the epigenome and could participate to plant adaptability.