秦岭地区核桃自然群体和栽培群体的遗传多样性及其演化关系——基于nrDNA ITS序列分析

Genetic Diversity and Evolutionary Relationship of Juglans regia Wild and Domesticated Populations in Qinling Mountains Based on nr DNA ITS Sequences

基于19个自然群体和10个栽培群体共359个个体的核糖体内转录间隔区（nr DNA ITS）序列分析,研究秦岭地区核桃的群体遗传多样性、群体遗传结构及单倍型地理分布。359条ITS序列上共有18个单倍型,表现出较低的遗传多样性（Hd=0.274,π=0.005 5）,群体间单倍型遗传多样性差异较大（Hd=0-0.679,π=0-0.017）。Network单倍型网络分析表明,单倍型14和单倍型7比较原始,且栽培群体与自然群体之间对古老单倍型H14与H7有着明显的共享现象,基因流较强（Nm=48.62）。综合中性检验及失配分析的结果,可推断在近期历史上秦岭地区核桃没有发生过群体扩张事件。AMOVA分析结果显示,秦岭地区自然核桃群体遗传变异主要存在于群体内（53.4%）,群体间遗传分化水平较低（GST=0.067）。单倍型最大简约树和邻接树均可将18个单倍型及所有核桃群体分成两大支。

A total of 359 rDNA ITS sequences were used to study the genetic diversity, population genetic structure and the geographical distribution of haplotype patterns of Juglans regia wild and domesticated populations. The results showed that： based on ITS sequences, 18 haplotypes were found in 29 populations. Nueleotide diversity （π） at species level was 0. 005 5, and haplotype diversity （Hd ） was 0. 274. The haplotype diversity was from 0 to 0. 679 in different populations. The gene flow （Nm = 48. 62） was fairly strong between wild and domesticated populations. Haplotype of network showed that haplotype 7 and haplotype 14 were relatively original in this study. Also, haplotype 7 and haplotype 14 were shared among different populations in wild and domesticated populations. The results of Neutrality test and mismatch distribution analysis showed that common walnut trees have not been expanded in recent history. The result of AMOVA depended on ITS showed that genetic variation of J. regia mainly occurred within wild populations, Gst was 0. 067. The maximum likelihood （ML） tree and neighbor-joining （NJ） tree showed all haplotypes and populations were divided into two clusters.