Abstract
The ddm1 mutation in Arabidopsis thaliana causes genome-wide DNA hypomethylation, and by succeeding self-pollination, various types of developmental abnormalities are observed. One of such developmental abnormalities, bonsai (bns) was caused by loss-of-function of BNS gene. Recent study revealed that BNS gene was ectopically hypermetylated in ddm1 background. Thus, ddm1 mutation has two opposite effect; genome-wide DNA hypomethylation and local DNA hypermethylation.
To dissect the mechanism of ddm1-induced DNA hypermethylation, we combined the ddm1 mutation with mutations in various components of DNA methylation machineries, such as DNA methyltransferases, RNAi machineries, and histone modifiers. Interestingly, mutations in known components of RdDM (RNA-directed DNA methylation) did not suppress the induction of hypermethylation into BNS locus. On the other hand, hypermethylation in BNS was not induced in ddm1 cmt3 and ddm1 kyp mutants. Our results indicate that BNS locus was hypermethylated by CMT3-KYP mediated pathway.
