Bud endodormancy in deciduous fruit trees:advances and prospects

Bud endodormancy is a complex physiological process that is indispensable for the survival,growth,and development of deciduous perennial plants.The timely release of endodormancy is essential for flowering and fruit production of deciduous fruit trees.A better understanding of the mechanism of endodormancy will be of great help in the artificial regulation of endodormancy to cope with climate change and in creating new cultivars with different chilling requirements.Studies in poplar have clarified the mechanism of vegetative bud endodormancy,but the endodormancy of floral buds in fruit trees needs further study.In this review,we focus on the molecular regulation of endodormancy induction,maintenance and release in floral buds of deciduous fruit trees.We also describe recent advances in quantitative trait loci analysis of chilling requirements in fruit trees.We discuss phytohormones,epigenetic regulation,and the detailed molecular network controlling endodormancy,centered on SHORT VEGETATIVE PHASE(SVP)and Dormancy-associated MADS-box(DAM)genes during endodormancy maintenance and release.Combining previous studies and our observations,we propose a regulatory model for bud endodormancy and offer some perspectives for the future.

High-quality genome assembly of 'Cuiguan' pear (Pyrus pyrifolia) as a reference genome for identifying regulatory genes and epigenetic modifications responsible for bud dormancy

Dormancy-associated MADS-box(DAM)genes serve as crucial regulators of the endodormancy cycle in rosaceous plants.Although pear DAM genes have been identified previously,the lack of a high-quality reference genome and techniques to study gene function have prevented accurate genome-wide analysis and functional verification of such genes.Additionally,the contribution of other genes to the regulation of endodormancy release remains poorly understood.In this study,a high-quality genome assembly for'Cuiguan'pear(Pyrus pyrifolia),which is a leading cultivar with a low chilling requirement cultivated in China,was constructed using PacBio and Hi-C technologies.Using this genome sequence,we revealed that pear DAM genes were tandemly clustered on Chr8 and Chr15 and were differentially expressed in the buds between'Cuiguan'and the high-chilling-requirement cultivar'Suli'during the dormancy cycle.Using a virus-induced gene silencing system,we determined the repressive effects of DAM genes on bud break.Several novel genes potentially involved in the regulation of endodormancy release were identified by RNA sequencing and H3K4me3 chromatin immunoprecipitation sequencing analyses of‘Suli'buds during artificial chilling using the new reference genome.Our findings enrich the knowledge of the regulatory mechanism underlying endodormancy release and chilling requirements and provide a foundation for the practical regulation of dormancy release in fruit trees as an adaptation to climate change.