米槁天然种群遗传多样性的ISSR标记分析

摘要

[目的]评价米槁(Cinnamomum migao H.W.Li)天然种群的遗传多样性,为其遗传资源的保护和利用提供理论依据.[方法]采用ISSR分子标记,对采自贵州的8个米槁天然种群及其62株个体的遗传多样性和遗传结构进行分析,基于遗传相似系数和遗传距离对8个种群进行UPGMA聚类分析,并对62株米槁建立PCoA散点聚类图.[结果]米槁8个天然种群通过19条引物扩增出167个多态性条带,多态性条带比例为89.78％.米槁种群间平均观测等位基因数为1.572 6,有效等位基因数为1.390 9,Nei's基因多样性指数为0.223 3,Shannon's多样数指数为0.328 2,多态性条带比例为57.26％,基因分化系数为0.263 6,米槁不同天然种群上述遗传多样性指标均显示为物种水平＞种群水平;8个米槁种群的遗传距离均不高(0.046 4～0.241 3),种群间的遗传变异程度较低;米槁种群间的基因流为1.396 8＞1,说明种群间存在基因流动,但种群间的遗传分化较小.UPGMA聚类结果显示,8个种群中镇宁(ZN)单独为一类,罗甸1(LD1)、罗甸2(LD2)、望谟1(WM1)、望谟2(WM2)聚为一类,册亨(CH)、荔波(LB)、贞丰(ZF)聚为一类,聚类结果反映出地理距离近的种群聚在一起;PCoA散点聚类图显示,62株米槁明显分为2个谱系,谱系1为罗甸2个种群,谱系2包含镇宁(ZN)、贞丰(ZF)、册亨(CH)、荔波(LB),望谟2个种群兼具2个谱系的遗传信息.[结论]米槁种群间和种内遗传多样性丰富,具有进一步改良的潜力.%[Objective] This study evaluated the genetic diversity of natural Cinnamomum migao H.W.Li populations to provide theoretical basis for protection and rational utilization of C.migao genetic resources.[Method] The genetic diversity and genetic structure of 8 natural populations and 62 individuals of C.migao from Guizhou were analyzed using ISSR molecular markers.Based on genetic identity and genetic distance,UPGMA cluster analysis was performed on the 8 populations and PCoA scatter point cluster diagram was established on the 62 plants.[Result] A total of 167 polymorphic bands were amplified by 19 primers from 8 natural C.migao populations,and the polymorphic band ratio was 89.78％.The mean observed number of alleles,effective number of alleles,Nei's gene diversity,Shannon's information index,polymorphicband ratio,and gene differentiation coefficient were 1.572 6,1.390 9,0.223 3,0.328 2,57.26％,and 0.263 6,respectively.Above genetic diversity indexes of different natural populations in species level were larger than those in population level.The genetic distances of the 8 populations were not high (0.046 4-0.241 3),and the genetic variations among populations were low.The gene flow among populations of 1.396 8 was larger than 1,indicating that there was a gene flow among populations,but the genetic differentiation among populations was small.UPGMA clustering showed that Zhenning (ZN) was one class,Luodian 1 (LD1),Luodian 2 (LD2),Wangmo 1 (WM1) and Wangmo 2 (WM2) belonged to one class,while Ceheng(CH),Libo (LB) and Zhenfeng (ZF) belonged to one class,which showed the populations with less distances clustered together.Principal coordinates analysis showed that 62 samples were di vided into two ancestries.Ancestry 1 had two populations of Luodian,ancestry 2 contained Zhenning (ZN),Zhenfeng (ZF) and Ceheng (CH),while the two Wangmo populations had genetic information of both ancestries.[Conclusion] C.migao has abundant genetic diversity among populations and species,and it has the potential for further genetic improvement.