Regulation of Bud Dormancy and Bud Break in Japanese Apricot (Prunus mume Siebold ^|^amp; Zucc.) and Peach [Prunus persica (L.) Batsch]: A Summary of Recent Studies

Bud dormancy allows most deciduous fruit tree species to avoid injury in unsuitable environments, synchronize their annual growth, and adapt to a temperate zone climate. Because bud dormancy affects next season’s fruit production and vegetative growth, it is considered one of the most important physiological factors that control fruit production. Recent global climate changes require us to better understand the genetic factors regulating bud dormancy, especially those that induce dormancy release and subsequent bud break. In this review, environmental factors that affect the seasonal dormancy depth of Japanese apricot (P. mume Siebold & Zucc.) and peach [P. persica (L.) Batsch] are first outlined. Next, recent progress of genetic, biochemical, and molecular biological studies of Prunus dormancy regulation is described. Recent advances in functional genomics have promoted the discovery of gene function and gene networks associated with bud dormancy regulation. A group of candidate genes for bud dormancy regulation, the DORMANCY-ASSOCIATED MADS-box (DAM) genes in Prunus, are focused. Recently reported expressional analysis suggests a significant role for DAMs in dormancy release and bud break of Japanese apricot and peach vegetative buds. Transformation studies of PmDAM6 have demonstrated that it has an inhibitory effect on the apical growth of poplar (Populus spp.). As bud dormancy is a quantitative polygenic trait, not only DAMs, but also other genes and gene networks appear to regulate bud dormancy. Ongoing and future studies will undoubtedly facilitate the unveiling of the molecular aspects of bud dormancy regulation in temperate fruit tree species of Prunus.