High-density Genetic Map Construction And QTL Mapping Of Fruit Size-related Traits Of ’JMS2’×’Xing16’ Population

Jujuba（Ziziphus jujuba Mill.）belongs to the Rhamnaceae（Rhamnaceae）genus（Ziziphus Mill.）.It is the original characteristics of Chinese forest fruit and is mainly distributed in 6 provinces of Xinjiang,Hebei,Henan,Shandong,Shanxi and Shanxi.My country has abundant jujube varieties,but lacks new varieties with excellent comprehensive traits.Variety selection is mainly through farmer selection,seed selection and hybrid breeding.The breeding cycle is long and difficult.In this study,167 hybrid progeny of male sterile line’JMS2’（♀）×wild jujube line’Xing 16’（♂）F₁ were used as materials,using WGS（whole genome resequencing）technology to develop SNP markers to construct a high-density genetic map of jujube trees.Investigate the phenotypic data of fruit weight,fruit longitudinal diameter,fruit transverse diameter,fruit shape index,Fruit stone weight,Fruit stone longitudial diameter,Fruit stone transverse diameter,Fruit stone index and edible rate for two consecutive years,carry out fruit size-related traits QTLs mapping,dig out SNP markers that are closely related to the target traits,accelerate the breeding process,and lay the foundation for targeted breeding and genetic improvement.The main findings are as follows:（1）A new high-density genetic map of jujube trees was constructed based on whole genome resequencing.A total of 1,569,033 SNPs were detected between the parents.The SNPs for Bin marker fit for CP and the depth more than 4X were 148,738.The marker which using for conducting high-density genetic map was 2398 Bin（including 116,312 SNP markers）.The total high-genetic map distance was1074.33 c M and average distance was 0.45 c M in 12 groups.（2）The phenotypic data of 9 traits for two years all showed normal or partial normal distribution,which was a quantitative trait controlled by multiple genes,and the coefficient of variation was between 1.85%and 42.60%.Among them,the transverse diameter of the fruit stone showed super-high genetic inheritance,the fruit shape index was low inherited,and the other traits were between the parents.（3）A total of 250 QTLs related to fruit size were detected in two years.The number of QTLs located in the linkage group in 2020 is more than that in 2019,and they are mainly distributed in the LG2,LG3 and LG6 linkage groups.Among them,the LOD threshold of 21 QTLs loci is≥3.5,which may be a major gene;there are 26 QTLs where QTLs regulating different traits appear in the same position in the same linkage group.（4）The three traits of single fruit weight,fruit transverse diameter and fruit shape index were stably expressed during the years.Among them,single fruit weight and fruit horizontal diameter are linked to the same marker Marker1316 at 122.75 c M of the LG6 linkage group,and the interpretation rate is above 10%;the fruit shape index has 4 overlapping sites in two years,and the phenotypic interpretation of 3 sites The rate is 10.5%-18.9%.