HYPERMETHYLATED SUPERMAN EPIGENETIC ALLELES IN ARABIDOPSIS

Mutations in the SUPERMAN gene affect flower development in Arabidopsi s. Seven heritable but unstable sup epi-alleles (the clark kent allele s) are associated with nearly identical patterns of excess cytosine me thylation within the SUP gene and a decreased level of SUP RNA. Revert ants of these alleles are largely demethylated at the SUP locus and ha ve restored levels of SUP RNA. A transgenic Arabidopsis line carrying an antisense methyltransferase gene, which shows an overall decrease i n genomic cytosine methylation, also contains a hypermethylated sup al lele. Thus, disruption of methylation systems may yield more complex o utcomes than expected and can result in methylation defects at known g enes. The clark kent alleles differ from the antisense line because th ey do not show a general decrease in genomic methylation.