DEMETHYLATION-INDUCED DEVELOPMENTAL PLEIOTROPY IN ARABIDOPSIS

The function of DNA methylation in higher plants was investigated by e xpression of a complementary DNA encoding a cytosine methyltransferase (MET1) from Arabidopsis thaliana as an antisense RNA in transgenic pl ants. This expression resulted in a 34 to 71 percent reduction in tota l genomic cytosine methylation. Loss of methylation was observed in bo th repetitive DNA and single-copy gene sequences. Developmental effect s included altered heterochrony, changes in meristem identity and orga n number, and female sterility. Cytosine demethylation prolonged both vegetative and reproductive phases of development. These findings impl icate DNA methylation in establishing or maintaining epigenetic develo pmental states in the meristem.