Molecular characterization of the SAUR gene family in sweet cherry and functional analysis of PavSAUR55 in the process of abscission

Small auxin up RNA(SAUR)is a large gene family that is widely distributed among land plants.In this study,a comprehensive analysis of the SAUR family was performed in sweet cherry,and the potential biological functions of PavSAUR55 were identified using the method of genetic transformation.The sweet cherry genome encodes 86 SAUR members,the majority of which are intron-less.These genes appear to be divided into seven subfamilies through evolution.Gene duplication events indicate that fragment duplication and tandem duplication events occurred in the sweet cherry.Most of the members mainly underwent purification selection pressure during evolution.During fruit development,the expression levels of PavSAUR16/45/56/63 were up-regulated,and conversely,those of PavSAUR12/61 were down-regulated.Due to the significantly differential expressions of PavSAUR13/16/55/61 during the fruitlet abscission process,they might be the candidate genes involved in the regulation of physiological fruit abscission in sweet cherry.Overexpression of PavSAUR55 in Arabidopsis produced earlier reproductive growth,root elongation,and delayed petal abscission.In addition,this gene did not cause any change in the germination time of seeds and was able to increase the number of lateral roots under abscisic acid(ABA)treatment.The identified SAURs of sweet cherry play a crucial role in fruitlet abscission and will facilitate future insights into the mechanism underlying the heavy fruitlet abscission that can occur in this fruit crop.