Overexpression of DEMETER, a DNA demethylase, promotes early apical bud maturation in poplar

The transition from active growth to dormancy is critical for the survival of perennial plants. We characterized a DEMETER‐like (CsDML) in chestnut (Castanea sativa Mill.) and its putative ortholog in hybrid poplar (PtaDML6), under the signals that trigger bud dormancy in trees. Short days and cold temperatures induced CsDML and PtaDML6. We performed phylogenetic and protein sequence analysis, gene expression profiling, and global 5mC methylation by immunofluorescence to evaluate the role of CsDML and PtaDML6.

Transgenic hybrid poplars overexpressing CsDML were produced and analysed. Overexpression of CsDML accelerated short‐day‐induced bud formation. Buds acquired a red‐brown coloration earlier than wild‐type plants, alongside with the up‐regulation of flavonoid biosynthesis enzymes and accumulation of flavonoids in the shoot apical meristem and bud scales. Our data show that the CsDML demethylase induces genes involved in bud formation needed for the survival of the apical meristem under the harsh conditions of winter.