大别山山核桃天然群体遗传结构的初步分析

利用RAPD分子标记技术检测了大别山山核桃3个天然居群的遗传多样性和遗传结构。20条10 bp随机引物共检测到238个扩增位点,其中多态性位点162个,多态位点百分率(PPB)为68.1%。居群水平Shannon’s多态性信息指数(I)介于0.2651~0.2801之间;居群水平Ne i’s基因多样性指数(H)介于0.1789~0.1890之间。遗传变异计算显示大别山山核桃居群间基因分化系数(Gst)为0.4063,分子方差分析(AMOVA)表明居群间基因分化水平为0.4177,居群间基因流(Nm)为0.7306,说明大别山山核桃大部分变异存在于居群内,居群间基因交流相对较少。这一结果符合大别山山核桃风媒、异交的繁育系统特点,但其居群间基因分化程度明显高于异交植物的平均水平(Gst=0.1930)。地理隔离、居群内近交及居群间基因流受阻可能是形成目前大别山山核桃天然群体遗传结构的主要因素。

RAPD Analysis for Natural Population Genetic Structure of Carya dabieshanensis

Random amplified polymorphic DNA(RAPD) markers were used to measure genetic diversity and genetic structure of 3 natural populations of Carya dabieshanensis 238 loci were identified by 20 RAPD primers,out of which 162 loci were polymorphic and accounted for 68.1 % of the total genetic diversity at species level.Shannon's information index(I) varied from 0.2651 to 0.2801,and Nei's gene diversity index(H) varied from 0.1789 to 0.1890 at population level.Gst analysis showed 0.4063 genetic variation among populations,which indicated that most of the variation(59.37 %) existed within populations.Nm=0.7306,which showed that the gene flow among populations was at relatively low level.An analysis of molecular variance(AMOVA) also showed 0.4177 differentiation among populations.The results above were consistent with the characteristics that C.dabieshanensis was an outcrossing and wind-pollinated plant.But its genetic differentiation parameter(Gst) was evidently higher than the mean value among populations of outcrossing and wind-pollinated plants(Gst=0.1930).The possible reasons for the genetic diversity and genetic structure of C.dabieshanensis at present were mainly related to the geographic isolation,inbreeding and limited gene flow.