Genetic Variation And QTL Mapping Of Fruit Characters Of Jujube Hybrid Progeny

Jujube（Ziziphus jujuba Mill.）is an economic forest fruit tree with rich nutrition and functional components.With the rapid development of the jujube industry,there is an urgent demand for high-quality jujube varieties.The traditional varieties selection is mainly based on local selection and seed breeding.The research on genetic theory and the establishment of a hybrid breeding technology system have accelerated the process of cultivating new varieties.The aim of this study was to optimize the quality of fresh jujube.The experimental materials were derived from 103 hybrid progeny of‘Dongzao’（♀）בJinsi 4’（♂）of jujube,which the genetic rules of 15 traits of the fruits were investigated,correlation analysis and principal component analysis were carried out to screen for superior strains.For hybrid F₁generation of 15 fruit characters including the single fruit mass（SFM）,fruit length（FL）,fruit diameter（FD）,fruit shape index（FSI）,single core mass（SCM）,core length（CL）,core diameter（CD）,core shape index（CSI）,edible rate（ER）,kernel rate（KR）,soluble solids（SSC）,soluble sugar（SSU）,organic acid（OAC）,vitamin C（VCC）and total flavonoids content（TFC）.In addition,QTL mapping for 15 fruit traits in hybrid offspring was conducted based on the high-density genetic linkage map.The main conclusions are as follows:The study of hybrid F₁generation found that some fruit traits showed wide separation,the single fruit mass,fruit length,fruit diameter,core length,core shape index,soluble sugar content tended to be lower parental inheritance.Fruit shape index,single core mass,and core diameter tended to be mesoparental inheritance.The soluble solids,organic acids,vitamin C,and total flavonoids content tended to be higher parental inheritance.The distribution of edible and kernel rate in the progeny was concentrated.The correlation analysis results of fruit traits showed that there was a strong correlation between fruit size and core size.There was a significant negative correlation between edible rate and kernel content.Vitamin C content had a significant positive correlation with total flavonoids content and a significant negative correlation with soluble solid content.The comprehensive evaluation analysis showed that fruit size,fruit shape index,core shape index,edible rate and fruit nutrients content could be the main indexes of fruit traits of hybrid progenies.According to the results,fruit quality evaluation and superior strains selection were carried out.The excellent strain numbers were J-48,J-47,J-2,J-163 and J-26.Using the interval mapping method in QTL analysis,15 fruit traits were located.A total of 206 QTLs were detected on the constructed high-density genetic linkage map of jujube and loci were found in 12 linkage groups.The fruit phenotypic traits detected for 63 QTLs,including 8 for single fruit mass,31 for fruit length,23 for fruit diameter,and 1 for fruit shape index.The core phenotypic traits detected for 58 QTLs,including 16 for single core mass,18 for core length,16 for core diameter,and 8 for core shape index.The edible rate detected for 4 QTLs,and 1 QTL was detected for kernel rate.The nutrients traits were detected for 81 QTLs,including 7 for soluble solids,31 for soluble sugars,5 for organic acids,17 for vitamin C and 21 for total flavonoids.When LOD≥3.5,there were 111 major QTLs.To sum up,the analysis of the inheritance law of fruit characters in jujube hybrid populations,as well as QTL mapping for the phenotypic traits of fruit and core,edible rate,kernel rate and nutrients content,these results provide theoretical reference for genetic breeding,gene screening and molecular marker development.