Construction Of Genetic Linkage Map And Mapping QTL For Some Traits In Chinese Jujube (Ziziphus Jujuba Mill.)

Chinese Jujube (Ziziphus jujuba Mill.), a precious germplasm resources originated from China, belongs to Ziziphus, Rhamnaceae family. The first high-density genetic linkage map in Ziziphus was constructed based on a F1 segregating population derived from a cross between two jujube varieties with good complex characters, Dongzao (Ziziphus jujuba Mill. cv. Dongzao) and Linyilizao(Ziziphus jujuba Mill. cv. Linyilizao). QTLs linked to some agronomic traits were located in the map.F₁ segregating population of 161 individuals was identified by AFLP silver staining technique from 165 Dongzao progenies of open pollination of Dongzao and Linyilizao thanks to the few germinating pollen with Dongzao and a lot with Linyilizao. 150 F₁ individuals were scored for marker polymorphisms. A high density genetic map was constructed using Joinmap3.0 setting CP (cross pollination population) type data based on the AFLP markers generated by 50 EcoRI/MseI primer pairs, 333 AFLP markers located on 14 linkage groups, with an average distance of 3.9cM between adjacent markers, covering a total distance of 1237.4cM of Chinese jujube genome. It was the first extensive genetic linkage map in Ziziphus to-date, the marker density of which could be used for mapping QTL linked to quantitative traits.110 putative QTLs was located in the genetic linkage map with MapQTL4.0 software using interval mapping method, 30 QTLs for length between nodes on different branches, 30 QTLs for some leafy traits, 13 QTLs for leaf NPK content, 16 QTLs for cold resistance and 21 QTLs for disease resistance, among them involved 87 QTLs with distance from the nearest AFLP marker between 0-1 cM, 20 QTLs with distance from the nearest AFLP marker between 1-5 cM, 29 QTLs with major effects, and 28 major QTLs co-located or closely linked with the nearest AFLP marker(with distance from the nearest AFLP marker between 0⁵cM).Genes would cluster together on the linkage groups for their similar functions, QTLs related to length between nodes on different branches and some leafy traits closely distributed on LG4, and 9 QTLs for leafy traits located on LG9, QTLs for cold-resistance apparently clustered at top or tail of related linkage groups, contrary to 13 QTLs related to leaf NPK content fell onto 10 linkage groups. 30 regions were detected, which two or more QTLs controlling different traits co-located or closely linked each other in the genetic linkage map.These results would be useful for interest gene cloning and marker-assisted selection for genetic improvement in Chinese jujube.