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[摘要]
目的 研究18个苦玄参种群的遗传多样性及亲缘关系,为苦玄参的资源评价及开发利用提供依据。方法 采用EST-SSR引物开发技术,利用SSR分子标记,分析18个种群的遗传多样性,并基于遗传距离对其进行聚类分析,明确各种群间的亲缘关系。结果 从100对EST-SSR标记中,筛选出具有多态性的引物48对。随机抽取20对具有多态性的引物对18个种群进行扩增,共扩增出71个等位基因,平均每对引物3.55个。各引物间多态位点百分数(P)为0~40.7%,平均19.9%;多态信息含量(PIC)为0~0.794 1,平均0.397 7;Shannon信息指数(I)为0~1.814 3,平均0.808 4。观测杂合度(Obs_Het)为0~0.442 3,平均值0.212 7;预期杂合度(Exp_Het)变化范围0~0.826 9,平均值0.455 8。18个种群群内近交系数(Fis)值为-0.095 3~0.663 9,平均0.159 2;总群体内亚群间近交系数(Fit)值为0.062 6~0.858 7,平均0.537 2;遗传分化系数(Fst)为0~0.686,平均0.449 6。基因流(Nm)在0.114 4~0.759 4,平均值为0.306 1。各种群基因多样性指数(Nei)为0~0.401 6、I为0~0.620 9,广西梧州最高,云南普洱龙潭乡最低。云南景洪勐龙镇和云南景洪景哈乡遗传距离最近,仅0.031 9;广西龙州和云南勐海县打洛镇遗传距离最大,为0.963 8。在遗传距离0.321 3处,可将18个种群分成4个群体,其中广西3个种群归入同一群体,云南勐满镇、勐伦镇及勐遮镇归为同一个群体,第3个群体为云南勐海县勐宋乡,其余种群归入第4个群体。结论 18个种群遗传分化水平不一致,各种群杂合度差异较大。种群间Nm较小,群体基因交换不大;群体内存在一定的近交率,种群亲缘关系受地理隔离影响较大。
[Key word]
[Abstract]
Objective To explore genetic diversity of and genetic relationships among 18 Picria felterrae populations to provide references for the resource assessment and utilization.Methods The genetic diversity of 18 P. felterrae populations were analyzed using the EST-SSR primer development technology and SSR molecular markers, and cluster analysis was performed based on genetic distances to determine the relationships among those populations.Results A total of 48 pairs of polymorphic primers were selected from 100 pairs of EST-SSR markers, of which 20 pairs were randomly selected and used for amplification of 18 populations. A total of 71 alleles were amplified, 3.55 alleles per primer. Among the primers, the percentage of polymorphic loci (P) varied from 0 to 40.7%, with an average of 19.9%; The polymorphism information content (PIC) varied from 0 to 0.794 1, 0.397 7 on average; The Shannon diversity information index (I) varied from 0 to 1.814 3, with an average of 0.808 4; Obs_Het varied from 0 to 0.442 3, with an average of 0.212 7; And the Exp_Het varied from 0 to 0.826 9, with an average of 0.455 8. For the 18 populations, the Inbreeding Coefficient (Fis) varied from -0.095 3 to 0.663 9, with an average of 0.159 2; The inbreeding coefficient of subgroups (Fit) varied from 0.062 6 to 0.858 7, with an average of 0.537 2; The genetic differentiation coefficient (Fst) varied from 0 to 0.686, with an average of 0.449 6; The gene flow (Nm) varied from 0.114 4 to 0.759 4, with an average of 0.306 1. For the 18 samples tested, the gene diversity index (Nei) varied from 0 to 0.401 6, the I varied from 0 to 0.620 9, Wuzhou Guangxi having the maximum value and Longtan Yunnan the minimum value. Menglong and Jingha, two towns in Yunnan, had the shortest genetic distance (0.031 9), whereas Longzhou Guangxi and Menghai Yunnan had the maximum genetic distance (0.963 8). The 18 populations could be divided into four groups at the location where genetic distance was 0.321 3. The three populations in Guangxi belonged to the same group, populations from Menglong, Menglun and Mengzhe of Yunnan belonged in the same group, populations from Mengsong Yunnan became an independent group, and the rest belonged in the fourth group.Conclusion The genetic differentiation levels of 18 populations were not consistent, and the heterogeneity difference was significant. The gene flow among populations was small, which indicated that the population gene exchange was low. A certain inbreeding rate exists among the populations. The relationship among populations was influenced by geographical isolation and environmental factors.
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[基金项目]
国家自然科学基金资助项目(31460074);国家自然科学基金资助项目(81573535);国家重点研发计划(2017YFC1704000);民族医药教育部重点实验室自主课题资助(KLEM-ZZ201805)