北京山区3种栎属植物居群遗传结构与基因渐渗研究

Genetic structure of populations and introgression of three Quercus species in mountainous area of Beijing

【目的】栎属植物种间经常发生种间杂交和基因渐渗现象,特别是同域分布的同组内栎树之间,这种情况会更加频繁。本文通过对北京山区3种栎属植物居群遗传结构遗传变异与遗传结构进行研究,为了解北京地区自然分布的栎属植物种间基因渐渗情况、种质资源现状以及经营管理提供有效数据。【方法】本文使用6对SSR引物对云蒙山、上方山和北农林场同域分布的304个蒙古栎、槲树、槲栎的居群遗传多样性、遗传结构和种间基因渐渗进行了研究。【结果】共检测到等位标记105个,每个位点的平均等位标记数(Na)为17.5个,期望杂合度(He)为0.660~0.911,平均为0.838,多态性信息含量指数(PIC)为0.632~0.903,平均为0.822,3种栎树在总体水平上具有较高的遗传多样性。在种的水平上,3种栎树的平均等位标记数(Na)为12.667~14.167,期望杂合度(He)为0.743~0.849,多态性信息含量指数(PIC)为0.725~0.826,3种栎属植物的遗传多样性水平为蒙古栎>槲树>槲栎。对7个栎树居群的遗传结构分析表明,遗传变异大部分发生在居群内。通过Structure软件对3种栎树种间基因渐渗进行分析,发现槲树-槲栎、槲树-蒙古栎和槲栎-蒙古栎这3个种对间均有基因渐渗发生。【结论】在北京山区分布的蒙古栎、槲树和槲栎这3种栎属植物之间存在普遍的、复杂的渐渗杂交现象。

[Objective]Interspecific hybridization and introgression often occur among species of Quercus,especially among sympatric Quercus more frequently.In this paper,the genetic structure and genetic variation of three species of Quercus in the mountainous area of Beijing were studied.It will provide effective data for gene introgression,germplasm resources and management of Quercus species naturally distributed in Beijing.[Method]304 natural oak samples of Quercus mongolica,Quercus dentate and Quercus aliena from Yunmeng Mountain,Shangfang Mountain and BUA(Beijing University of Agriculture)Forest Farm were selected as the material,and six pairs of SSR primers were used to study the genetic diversity,genetic structure and introgressive hybridization among populations.[Result]A total of105 alleles were detected,the average number of alleles(Na)of each locus was 17.5,the expected heterozygosity(He)was 0.660-0.911,the polymorphism information content index(PIC)was 0.632-0.903.The three oaks had high genetic diversity at the overall level.At the species level,the average allele number(Na)of the three oaks was 12.667-14.167,the expected heterozygosity(He)was 0.743-0.849,the polymorphism information content index(PIC)was 0.725-0.826,the genetic diversity level of the three species of oaks was Q.mongolica>Q.dentate>Q.aliena.The genetic structure analysis of 7 populations of Quercus showed that most of the genetic variation was in local populations.The genetic introgression analysis by structure software found that the gene introgression occurred among three pairs of Q.mongolica,Q.dentate and Q.aliena.[Conclusion]There is a common and complex phenomenon of introgression hybridization among Q.mongolica,Q.dentate and Q.aliena in Beijing mountainous area.