广西境内马褂木天然群体遗传多样性的ISSR分析

ISSR analysis on genetic diversity of Liriodendron chinense natural populations in Guangxi

关键词:  马褂木， 天然种群， ISSR标记， 遗传多样性， 遗传分化

Key words:  Liriodendron chinense, natural population, ISSR marker, genetic diversity, genetic differentiation

摘要:

为弄清广西境内马褂木（Liriodendron chinense）天然群体的遗传多样性及分布情况，该研究运用ISSR分子标记，对广西境内现存的6个野生马褂木种群进行遗传多样性分析及评价。结果表明：广西马褂木群体具有较丰富的遗传多样性，6个参试群体的平均（及总体）有效等位基因数（Ne）、Nei’s 基因多样度（H）和Shannon信息指数（I）分别为1.454 1（1.633 7）、0.257 6（0.363 3）和0.378 6（0.529 3）；群体间存在基因流动但水平有限（Nm=1.218 4），使群体间存在较高遗传分化（Gst =0.291 0）；聚类分析（UPGMA）将6个天然群体分为东部（全州QZ、资源ZY及融水老堡RS L）、西部（融水安太RS A、环江HJ及乐业LY）两组，其中东部组具有较低遗传多样性及较高的遗传分化，可能受到较强的人为干扰；Mantel检验表明群体间符合距离隔离模式（R=0.545, P=0.043），表明人为破坏导致的生境碎片化是造成广西马褂木天然群体遗传分化的重要原因。针对广西马褂木天然群体较丰富的遗传多样性及较高的遗传分化，除了考虑对遗传多样性较高群体（如RS A及HJ）进行原地保护外，宜对各群体采集种子或穗条，统一营建基因资源收集区，以供后续育种及生产利用。

Abstract:

In order to understand the genetic diversity and distribution model of Liriodendron chinense natural population in Guangxi Zhuang Autonomous Region, the genetic diversity and structure of six natural populations were analyzed by using ten ISSR markers. The results showed that there were abundant genetic diversity in six Liriodendron chinense natural populations. The average (or total) effective number of alleles (Ne), Nei’s gene diversity (H) and Shannon information index (I) of six populations were 1.454 1 (1.633 7), 0.257 6 (0.363 3) and 0.378 6 (0.529 3). A limited gene flow (Nm=1.218 4) resulted in a high genetic differentiation (Gst=0.291 0) among populations. The six populations were divided into two groups depending on cluster analysis (UPGMA method). One group (west group) contains the populations near the west (RS A, HJ and LY) and the other (east group) included the populations near the east (QZ, ZY and RS L). The east group had a lower genetic diversity and higher differentiation than the west one, which probably implied that populations in east group were strongly disturbed by human activities. Mantel test (R=0.545, P=0.041) displayed a significant isolation by distance model among populations, which also implied that habitat fragmentation due to human activities was an important factor for a highly genetic differentiation among populations. In the light of abundant genetic diversity and highly genetic differentiation on L. chinense populations in Guangxi, not only in situ conservation for the populations with abundant genetic diversity (e.g. RS A, HJ) is critical, but also ex situ conservation by seeds or cuttings collecting for all populations is also essential for further breeding and propagation.