Expression profiling of DNA methyltransferase genes in wheat genotypes with contrasting drought tolerance

DNA methylation is a reversible epigenetic mechanism that affects important developmental processes and stress-related events in living organisms. The process of cytosine methylation is catalysed by DNA methyltransferases that are structurally and functionally conserved in all eukaryotes. This study assessed the effect of drought stress and subsequent rewatering on the transcription of DNA methyltransferase coding genes (TaMET1, TaMET2a, TaMET2b and TaMET3) in wheat genotypes with contrasting drought tolerance. The applied drought stress led to changes in leaf water deficit in a variety-specific manner. Two of the wheat genotypes, Farmer and Bojana, performed as sensitive to drought, the other two, Yoana and Guinness, were considered as drought tolerant. Under drought and after recovery, the drought-sensitive genotypes exhibited high variability in the expression level of TaMET1, TaMET2b and TaMET3. The TaMET1 transcripts increased approximately three times under dehydration, compared to the controls. The drought-tolerant varieties had a relatively stable transcription of DNA methyltransferase genes. The TaMET1 expression was higher in the controls of tolerant varieties, compared to the sensitive genotypes, and did not change under drought exposure and after rewatering. The lowest response to dehydration had TaMET2a, which only slightly varied in the sensitive genotypes under dehydration. The results point to unique biological functions and diverse roles of the wheat DNA methyltransferases in drought conditions that mainly correlated with the level of drought tolerance of the studied genotypes.