Effect of desiccation on the dynamics of genome-wide DNA methylation in orthodox seeds of Acer platanoides L

5-methylcytosine, an abundant epigenetic mark, plays an important role in the regulation of plant growth and development, but there is little information about stress-induced changes in DNA methylation in seeds. In the present study, changes in a global level of m5C were measured in orthodox seeds of Acer platanoides L. during seed desiccation from a WC of 1.04 to 0.05–0.06 g H2O·g−1 dry mass (g·g−1). Changes in the level of DNA methylation were measured using 2D TLC – based method. Quality of desiccated seeds was examined by germination and seedling emergence tests. Global m5C content (R2) increase was observed in embryonic axes isolated from seeds collected at a high WC of 1.04 g·g−1 after their desiccation to significantly lower WC of 0.17 and 0.19 g·g−1. Further desiccation of these seeds to a WC of 0.06 g·g−1, however, resulted in a significant DNA demethylation to R2 = 11.52–12.22%. Similar m5C decrease was observed in seeds which undergo maturation drying on the tree and had four times lower initial WC of 0.27 g· g−1 at the time of harvest, as they were dried to a WC of 0.05 g·g−1. These data confirm that desiccation induces changes in seed m5C levels. Results were validated by seed lots derived from tree different A. platanoides provenances. It is plausible that sine wave-like alterations in m5C amount may represent a specific response of orthodox seeds to drying and play a relevant role in desiccation tolerance in seeds.