Effects Of Two Tree Shapes Treatments On Development Of Young Apple Trees And Identification Of Apple MCU Family

In this study,3-year-old‘Yanfu 3’Y-shape（YS）and Tall spindle shape（TS）apple young trees（Malus?×?domestica Borkh）were used to evaluate various morphological and physiological related parameters.The germination rate,flowering rate,annual branch length,annual branch diameter,and annual branch internode length of the Y-shape（YS）and Tall spindle shape（TS）apple young trees were measured.Furthermore,the total carbon and nitrogen contents,C/N ratio,endogenous hormones content,and expression levels of flowering genes in spur buds on the main trunks were evaluated.Moreover,a comprehensive evaluation was designed to characterize the effects of tree shapes on the development and flowering of young apple trees.The findings of the present study would practically valuable for tree shape selection in apple production.We also identified five MdMCU genes,which laid the foundation for further study on the function of these genes.The main results of this study are divided into the following parts:1.The long branch ratio,new shoot diameter of main trunks,and new shoot annual growth of main trunks was significantly higher in TS apple trees as compared with YS apple trees.The YS apple trees exhibited relatively higher short shoot ratio and flowering rate on the main trunks compared with TS apple trees.We found no significant difference among the other indexes in the two studied apple tree.However,the C/N ratio in spur buds on the main trunks of YS apple was higher than TS apple trees.YS trees shared significantly higher ABA and ZT contents all in spur buds on main trunks than TS trees at 50 days after flowering.The content of GA₃ and IAA in spur buds on main trunks of TS apple trees,which were all significantly higher than YS apple trees at 50 and 70 days after flowering.In addition,the expression of MdFT in spur buds on the main trunks of YS apple trees was higher by 46.47%than TS apple trees at 50 DAF.The expression of MdAP1 in spur buds on the main trunks of TS trees was relatively lower than YS apple trees at 70d after flowering.Furthermore,we also noticed that the expression of MdLFY in spur buds on the main trunks of YS apple trees was significantly higher than TS apple trees at 30,50 and 70 DAF.The expression of MdSOC1 in spur buds on the main trunks of YS apple trees obvious higher than TS apple trees at 50 and 90 DAF.In this paper,the comparison of high spindle and YS apple young trees concluded that YS apple young trees exhibit early short branches characteristic as compared with spindle shape apple trees.This study provided a basis for screening the tree shape that forms flower buds easily.However,the exact differences between the two tree-shaped related parameters in ON-year and OFF-year,and the effect of the growth environment on young apple trees during flowering have not been investigated.2.We performed genome-wide identification,bioinformatics analysis,and gene expression profiling of MdMCU in apple.Five members of this gene family were identified and divided into two phylogenetic branches,The number of introns varied from 1 to 4 were found and seven motifs are commonly present in all MdMCUs.The upstream regions of MdMCUs all showed the presence of ABA responsive and light responsive cis-element.The results of tissue-specific expression analysis based on public data indicate that MdMCUs have wide expression profiles in various tissues.It would be laid the foundation for further functional studies of these MdMCU genes.