ISOLATION OF DNA-METHYLTRANSFERASE GENES AND THEIR PROMOTER SEQUENCES FROM STRAWBERRY (FRAGARIA × ANANASSA DUCH.)

DNA methylation in plants is required for normal development and plays important roles in regulating gene expression. Patterns of methylation are established by de novo methyltransferase (DRM) and maintained by maintenance methyltransferase (MET1) activities. In this study, two putative sequences of DNA methyltransferase genes, FaMET1a and FaDRMa were isolated initially from strawberry (Fragaria×ananassa Duch.) using chromosome-walking procedure and rapid-amplification of cDNA ends (RACE). Structural conservation of the amino acid sequence between FaMET1a and PpMET1, and that between FaDRMa and NtDRM1 suggested that they could function as DNA methyltransferase. By constructing plasmids with 5’ regions from FaMET1a and FaDRMa fused to the coding sequence of a gene encoding β-glucuronidase (GUS), it was demonstrated that the regions upstream of FaMET1a and FaDRMa translational initiation codons contained the 5’-regulatory elements necessary for high-level GUS expression in transiently transformed strawberry fruits.