榧树居群遗传多样性的cpSSR分析

Genetic diversity of Torreya grandis populations as revealed by chloroplast microsatellite markers

【目的】探讨全球气候变化和人类活动干扰对榧树遗传多样性的影响。【方法】采用叶绿体基因组SSR分子标记的方法,对榧树自然分布区10个居群的遗传多样性和遗传结构进行了研究。【结果】5个cpSSR多态性位点共检测到17个等位基因,可组成28个单倍型。单倍型H3和H13是所有居群共有的单倍型。榧树叶绿体基因组的遗传多样性HE为0.157(0.098~0.211),明显低于其他针叶树种叶绿体基因组的遗传多样性(0.370)。榧树的遗传多样性主要分布于居群内(97.95%),居群间的遗传分化GST为0.020 3,低于其他37种针叶树种的遗传分化(0.165)。【结论】榧树居群经历了历史瓶颈效应。武夷山、黄山、会稽山和天目山等山区可能是榧树在第4纪气候振荡期的孑遗地。瓶颈效应和遗传漂变是形成榧树单倍型分布式样的重要原因。

【Objective】 The aims of this study were to investigate the effect of historic climate changes and habitat fragmentation on genetic diversity of Torreya grandis. 【Method】 Ten populations were sampled over its entire natural range for genetic analysis using five chloroplast microsatellites loci. 【Result】 A total of28 haplotypes designed by 17 alleles at five polymorphic loci were detected across 300 individuals of the ten populations sampled. A single, common, and often frequent haplotype(H3 & H13) was detected in all extant populations of T. grandis. The genetic diversity(HE) of cpDNA detected within populations was0.157(0.098 to 0.211), lower than that in other eight conifer species previously reported. Based on paternally inherited markers, a lower level of genetic differentiation(0.020 3) was found in T. grandis than those previously reported for 37 other conifer species(0.165). Moreover, AMOVA analysis revealed that a significant amount of genetic diversity can be attributed to variation among populations(2.05%). 【Conclusions】 In mountain regions such as Wuyi, Huangshan, Tianmushan and Kuaijishan mountains, possibly during the Last Glacial Maximum, a bottleneck may have been generated by repeated climatic oscillations and genetic drift may have played significant roles in shaping current haplotype distribution patterns.