Key Genes Selection Associated With Weeping Trait Of Mei

Mei(Prunus mume),a traditional Chinese woody plant,due to its rich flower colors and branch types,is an important landscape ornamental plant.Weeping P.mume is one of the cultivar groups,characterized as distinct weeping branches with unique ornamental value.Current reports on the weeping trait of P.mume have indicated that it is associated with one main-effect gene and several micro-effect genes on chromosome 7.Although the phenotype of branches,through the whole genome resequencing of mei,has been associated with 13 candidate gene,there is still a lack of comprehensive explanation of the weeping phenotypic trait.This study adopted the group of F1 generation between P.mume 'Liuban' x 'FenTai ChuiZhi' as the research object.Firstly,two branch growth models,based on morphological data,of weeping and upright mei were proposed.The angles of branches,at different sites,were calculated according to the model and then were conducted,as a phenotypic trait,with a genome-wide associated analysis(GWAS).Secondly,an experiment on exogenous plant hormones,IAA and GA3,affecting one-year mei branches,was proposed,along with transcriptional and bioinformatics technologies,to compare the differential expression genes(DEGs)between weeping and upright mei.Lastly,an enrichment analysis using online databases was implemented,in addition to the results of RNA-Seq,to select key genes affecting the weeping phenotypic trait in mei.The main results can be summarized as follows:(1)Two growth models of weeping and upright mei branches were established,meaning a cubic function and an exponential function were adopted to describe the growth condition of weeping and upright mei branches.The angles at the third point were proven to be adequate as the phenotypic trait for the GWAS analysis within the whole-genome resequencing mei group.7 SNPs in candidate region of QTL results were selected.(2)The exogenous IAA plant hormone can change the angles of both weeping and upright mei branches.However,the exogenous GA3 can affect only the upright mei branches,while the weeping mei branches are not sensitive to exogenous GA3.External factors affecting the slope angle of mei branches are,from the highest to the lowest effect,arranged as IAA,phototropism and GA3.(3)The weeping phenotypic trait of mei is considered to be associated with the phenylpropanoid biosynthesis pathway,the plant hormone signal transduction pathway as well as the starch and sucrose metabolism.With a focus on the phenylpropanoid biosynthesis pathway,the PER genes,involved in the peroxidase process,are associated with the weeping trait as well as the exogenous GA3.The PER genes are,therefore,considered as the key genes associated with the weeping trait of mei.This paper is,initially,crucial for exploring the regulation mechanism,in response to plant hormones,of weeping trait of P.mume on molecular level,which will further provide solid evidence for the growth mechanism of branches towards gravitropical direction.In addition,this study will contribute to the breeding of ornamental plants with a weeping trait.