THE METHYLATION PATTERN OF A CYTOSINE DNA-METHYLTRANSFERASE GENE IN ARABIDOPSIS-THALIANA PLANTS

Using a PCR-amplified 5'-end proximal 600-bp fragment and two cDNA clo nes of cytosine DNA-methyltransferase gene of Arabidopsis thaliana as specific probes in hybridization with plant DNA samples, hydrolyzed by methylation-sensitive restriction endonucleases HpaII and MspI, it ha s been established that CCGG sites located in the 5'-end proximal part of cytosine DNA-methyltransferase gene are highly methylated at-inter nal C and less but detectably methylated at external C residues. On th e contrary, all CCGG sites in 3'-terminal half of the coding region we re found to be unmethylated at both external and internal C residues. No significat differences between methylation patterns of cytosine DNA -methyltransferase gene in various organs (leaf stem; newer) of the Ar abidopsis thaliana plant were detected.