Abstract
In plant genome, cytosine methylation is found not only at CG sites, but also at CNG and CNN sites. Cytocine DNA methylation at CNG sites is thought to be important especially for transposon silencing. Chromomethylase, which is regarded as a plant specific class of DNA methyltransferase so far, mainly controls CNG methylation. In Arabidopsis, Chromometylase 3 (CMT3) is a main regulator of CNG methylation. To investigate how CNG methylation works in rice genome, which has larger amount of transposons than that of Arabidopsis, we isolated a loss-of-function mutant of OsMET2a, the functional rice ortholog of CMT3. The phenotypes of osmet2a mutants observed suggested the importance of roles of CNG methylation in plant species having transposon-rich genome.
