Physiological functions of plant DNA methyltransferases

Abstract

Epigenetic regulation is defined as mechanisms that control gene expression without altering base sequences. Cytosine methylation, chromatin remodeling, and modifications at the N-termini of core histones are key factors in this regard. Epigenetic modifications are found throughout the eukaryotes, suggesting that they developed at an early stage in biological evolution, although actual molecular mechanisms show considerable variation among species. In particular, plants are unique in establishment and maintenance of epigenetic states, as exemplified by species-specific enzymes that catalyze DNA methylation. Since the function and diversity of DNA methyltransferases in individual species are not fully understood, I here summarize recent findings in plant epigenetics, focusing on DNA methyltransferases classified into three major groups. Their possible biological functions are also discussed with reference to histone modification and chromatin remodeling.