青藏高原地区的青杨遗传多样性研究

Phylogeography of Populus cathayana from the Qinghai-Tibetan Plateau based on cpDNA sequence

利用叶绿体DNA标记对青藏高原地区青杨的14个野生居群开展谱系地理学研究,分析该区域青杨的遗传结构和居群动态,旨在揭示其在第四纪冰期的演化历史,为种质资源评价、遗传保护策略的制定等提供理论依据。提取青杨基因组DNA,cpDNA非编码区atpH-atpI和rbcL片段经扩增、检测、纯化和测序后获得序列,统计cpDNA联合序列的变异位点并确定了13个单倍型;分子变异分析显示青杨的遗传变异主要存在于居群间而非居群内;研究范围内青杨单倍型之间不存在谱系地理关系,且歧点分布分析和中性检测均未检测到青杨发生过近期居群扩张。青杨的遗传分布和地理分布之间没有显著相关性,可能是由于在研究区域内存在多个微型避难所所致,如祁连山脉和横断山脉地区就可能为青杨的冰期微型避难所,而这些区域也是冰期后居群回迁和扩散的发源中心。

Phylogeography study of P.cathayana′14 wild populations in Qinghai-Tibet Plateau was developed by using chloroplast DNA markers.The genetic structure and population dynamics were analyzed in order to reveal its evolutionary history during the Quaternary Glaciation to provide theoretical basis for germplasm resource evaluation and genetic protection strategy formulation.The genomic DNA of P.cathayana was extracted,then the atpH-atpI and rbcL fragments of non-coding region were amplified,detected,purified and sequenced.The mutation sites of the combined sequence of cpDNA were counted and 13 haplotypes were identified.Molecular variation analysis showed that genetic variation mainly existed among populations rather than within populations.There was no phylogenetic relationship between haplotypes in this study,and no recent population expansion was detected by bifurcation analysis and neutral detection.There is no significant correlation between genetic distribution and geographical distribution of P.cathayana.This may be due to the existence of multiple micro-shelters in the study area.For example,the Qilian and Hengduan Mountains may be micro-shelters for P.cathayana during the glacial period,and these areas are also the origin centers of population migration and diffusion after the glacial period.