Identification of QTLs for chilling and heat requirements for bud dormancy release in Prunus mume and their co-localization with the DAM6 eQTL

Bud dormancy is an important developmental stage that affects the blooming date (BD) and leafing date (LD) in fruit trees. Recent global climate change may affect the progress of dormancy, and the BD and LD. However, the genetic factors controlling the chilling requirement (CR) and heat requirement (HR) for dormancy release are yet to be elucidated. In previous study, we identified significant QTL for leaf bud CR and HR, and LD on LG4 of Japanese apricot (Prunus mume) (Kitamura et al., 2018). Here, we further tested the genomic synteny of the QTL region between Japanese apricot vs. peach (P. persica), and Japanese apricot vs. sweet cherry (P. avium). Our comparative genomic analysis suggested that 751, 635, and 509 genes were conserved in common in the genomes of three Prunus species, Japanese apricot, peach and sweet cherry genomes, respectively, in corresponding regions of Japanese apricot QTLs for dormancy-related traits including CR on LG4. Co-localization of significant QTLs controlling PmDAM6 expression with CR, HR and LD on LG4 was also supported. Our WGCNA analysis using published microarray data (Habu et al., 2014) identified the QTL interval genes showing expression patterns correlated with PmDAM6. Of these, 29 genes were annotated as transcription factors. Further characterizations should be conducted in genes located in this QTL interval, which will provide the clues to understand the genetic regulation of bud dormancy in Prunus.