关键词: 森林草莓, N6–腺嘌呤甲基化（6mA）, N6–腺嘌呤甲基转移酶, 系统进化, 逆境胁迫

Abstract: DNA methylation on the sixth position of the purine ring in adenine[N6-methyladenine （6mA）]is an epigenetic modification widely present in both eukaryotes and prokaryotes，but our understanding in its function in plants is limited. We applied bioinformatic approaches to identify and analyze the two classes of putative N6-adenine DNA methyltransferase genes（three MT-A70 and two DAMT genes）in woodland strawberry（Fragaria vesca）. Phylogenetic analysis and chromosome positioning on those 6mA DNA methyltransferase genes from bacteria，fungi，animals and plants showed that F. vesca MT-A70 genes could be classified into three subfamilies，which existed before the diversification of plants and animals. Two DAMT genes were generated by a species-specific tandem duplication，and the proteins structure changed rapidly. It is speculated that the function of the DAMT protein has diversified during the evolutionary process. The analysis on transcriptome data suggested that each gene had specific spatiotemporal expression and was responsive to cold and heat stresses. The expression of one DAMT gene was relatively higher in fruits and was up-regulated as fruit matured，indicating that it may participate in the regulation of fruit ripening. In addition，the expression levels of the five 6mA methyltransferase genes were significantly changed under cold and heat stresses. Thus，it is speculated that MT-A70 and DAMT genes may be involved in the growth and development of F. vesca and its responses to cold and heat stresses.

Key words: Fragaria vesca, N6-adenine methylation, N6-adenine DNA methyltransferase genes, phylogenetic evolution, abiotic stress