陕北枣品种群遗传结构的SSR分析

SSR analysis on genetic structure of Chinese jujube in North Shaanxi

【目的】在分子水平上研究陕北枣品种群遗传结构,揭示品种群分化与品种间的亲缘关系。【方法】选取陕北4个区域(县)8个枣品种群的54份种质叶片为材料,采用7对SSR引物,研究品种群的遗传结构。【结果】基于4个地理区域的枣种质平均观测杂合度(Ho,0.909)大于平均期望杂合度(He,0.634),平均Shannon’s信息指数(I)为1.141,固定系数与近交系数均为负值;佳县品种的有效等位基因数(Ne)、He和I均最小,延川最大;狗头枣品种群的Ne、He和I均最小。供试枣品种地理区域内变异(97%)和品种群内变异(91%)分别大于地理区域间(3%)和品种群间(9%)的分化;且品种群内变异(91%)小于地理区域内变异(97%)。品种群遗传分化系数(0.136)大于地理区域(0.042),而品种群平均基因流(1.584)小于地理区域(5.653)。在遗传距离为0.13处,地理区域UPGMA聚为2个类群:清涧-米脂-佳县类群和延川类群;在遗传距离0.99处,品种群UPGMA聚为2个类群:团枣-木枣类群和狗头枣类群。NJ聚类分析将54份枣种质分为2类,延川、清涧和米脂团枣聚在一起,佳县所有枣种质均聚在第Ⅰ类,且各品种群亲缘关系很近;狗头枣品种群与其他品种群亲缘关系较远。【结论】陕北枣属中度杂合,遗传多样性丰富,变异程度较高,近交程度很低。供试枣品种交流频繁,地理区域间遗传分化低,品种群间分化程度高;枣品种遗传关系与地理区域无明显关系,与品种群密切相关。

【Objective】The purpose of this study was to elucidate the genetic structure of Chinese jujube at molecular level, and reveal the relationship between genetic differentiation and cultivars.【Method】Using 7 pairs of SSR primers,54 germplasms from 4 geographical regions and 8 cultivar groups along the Yellow River in North Shaanxi were selected to assess their genetic structure.【Result】The mean observed heterozygosity of the 4 regions （Ho,0.909） was higher than the mean expected heterozygosity （He,0.634） with the mean Shannon’s information index （I） of 1.141 and negative mean fixation index and inbreeding coefficient.The highest effective number of alleles （Ne）,I and He were found in Jiaxian while the lowest were found in Yanchuan.Goutouzao had the lowest in Ne,I,and He among all cultivars.The genetic variation in variety group （91%） was less than that in geographic region （97%）,and they both were much higher than differentiation among groups （3% and 9%）.Genetic differentiation coefficient of cultivar groups （0.136） was greater than that of geographical regions （0.042）,while mean gene flow among cultivar groups （1.584） was less than that among geographical regions （5.653）.When the Nei’s genetic distance was 0.13,the 4 geographical regions were clustered into 2 groups：Qingjian-MizhiJianxian group and Yanchuan group.When the Nei’s genetic distance was 0.99,8 cultivar groups UPGMA were divided into 2 clusters：Tuanzao-Muzao group and Gouzao group.Based on neighbor-joining method,54 germplasms were clustered into 2 groups.Tuanzao varieties from Yanchuan,Qingjian and Mizhi were in one group while all varieties from Jianxian were in one group,highlighting a close affinity among cultivar groups while Goutouzao was distantly related with other cultivars.【Conclusion】Jujubes planted in North Shaanxi had moderate heterozygosity,high genetic diversity,high variability,and low inbreeding degree.With considerable gene flow and narrow differentiation among geographical regions,multivariate genetic relationships among accessions were not correlated with geographic regions,but were closely correlated with cultivar groups.