AFLP analysis of genetic relationship and discrimination of Chinese jujube germplasm resources.

摘要

Chinese jujube (Ziziphus jujuba Mill.) is a popular fruit tree originated from China. Many cultivars have been developed during its long history of cultivation. Unfortunately, the nomenclature and seedling trade are confused due to their extreme similarity in morphology. In this report, 58 jujube cultivars and 2 wild types of sour jujube (Ziziphus acidojujuba C.Y. Cheng et M.J. Liu) were analyzed using fluorescent-labeled AFLP marker to determine their relationship. Of 40 AFLP primer combinations screened, 9 were selected for subsequent analysis based on the number and quality of polymorphic fragments they amplified. A total of 1118 AFLP markers between 100 to 450 base pairs (bps) were generated, of which 1066 (95.35%) were polymorphic. The number of amplified band was different between cultivars with an average of 490. The analysis showed that abundant genetic diversity exists among cultivars. The genetic similarity coefficients (Nei and Li's) ranged from 0.4712 to 0.8670. Using UPGMA clustering method, 60 germplasms were placed into four different clusters. The 2 sour jujube types were distinctly different from all other Chinese jujube cultivars and grouped in cluster SZ, which indicated that sour jujube had farther genetic distance with Chinese jujube cultivars and should be classified as an independent species. Fifty seven Chinese jujube cultivars grouped into two major clusters at 0.7025 similarity coefficients and showed close genetic relationship each other. Fresh cultivars, dry cultivars and ornamental cultivars showed insignificant differences in molecular level. Sucuizao and Kongfusucuizao were very close genetically. Jidanzao from Henan and Hunan provinces had farther genetic distance and they were different cultivars. Shiyuehong was separated with other cultivars firstly in clustering. PCOA (Principal Coordinates Analysis) also supported the UPGMA cluster-grouping result. The study could be useful in jujube germplasm discrimination, conservation and new cultivar breeding.