沙棘7个亚种与26个重要品种的遗传多样性

利用14个微卫星标记分析了沙棘Hippophae rhamnoides 7个亚种和26个大果沙棘品种的遗传多样性，采用系统发育树和贝叶斯聚类方法分析了这些个体的聚类情况。结果显示:中国沙棘H. rhamnoides subsp. sinensis和云南沙棘H. rhamnoides subsp. yunnanensis遗传多样性水平最高，高加索沙棘H. rhamnoides subsp. caucasica最低。系统发育树将所有个体聚为2个大支:亚洲分支和欧洲分支。大部分大果沙棘品种与亚洲的蒙古沙棘H. rhamnoides subsp. mongolica聚为1支，少量个体位于亚洲分支和欧洲分支之间。贝叶斯聚类分析将所有个体划分为3组或7组:分3组时，中国沙棘和云南沙棘为一组，蒙古沙棘和大部分大果沙棘品种为一组，溪生沙棘H. rhamnoides subsp. fluviatilis，高加索沙棘和海滨沙棘H. rhamnoides subsp. rhamnoides为一组；分7组时，除海滨沙棘由溪生沙棘组和高加索沙棘组共同构成外，其他亚种和大果沙棘品种各自为一组，并发现少量组间混合基因型。表明沙棘种下亚种间分化明显，亚洲和欧洲分布的沙棘亚种间的分化尤为明显；大果沙棘品种大部分源于蒙古沙棘亚种，个别品种可能为蒙古沙棘和欧洲沙棘亚种间的杂交后代。

Genetic variation of 7 subspecies and 26 important cultivars in Hippophae rhamnoides

Hippophae rhamnoides have important ecological, economic and social benefits, so it is essential to understand the genetic variation of the species. Genetic diversity on 14 microsatellite loci was estimated for seven H. rhamnoides subspecies and 26 big grain sea buckthorn cultivars. The clustering of these individuals was analyzed by phylogenetic tree and Bayes cluster. Results indicated that H. rhamnoides subsp. sinensis had the highest genetic diversity, followed by H. rhamnoides subsp. yunnanensis; H. rhamnoides subsp. caucasica had the lowest genetic diversity. The phylogenetic tree based on individual genotypic distance classified all individuals into two big clades according to distribution, the Asian clade and the European clade. Most big grain sea buckthorn cultivars clustered with H. rhamnoides subsp. mongolica individuals collected from the Asian clade with a few individuals located between the two clades. The Bayesian cluster analysis found that all individuals could be classified into three or seven groups. For three groups, group one consisted of H. rhamnoides subsp. yunnanensis and H. rhamnoides subsp. sinensis; group two had the most cultivars and H. rhamnoides subsp. mongolica; and group three was H. rhamnoides subsp. fluviatilis, H. rhamnoides subsp. caucasica, and H. rhamnoides subsp. rhamnoides. For seven groups, all subspecies were classified into a different group with a few hybrids, and only H. rhamnoides subsp. rhamnoides showed a hybrid ancestry between H. rhamnoides subsp. fluviatilis and H. rhamnoides subsp. caucasica. There were also a few groups with mixed genotypes. Thus, genetic divergence among these seven H. rhamnoides subspecies was important, especially between subspecies distributed in different continents; whereas, big grain sea buckthorn cultivars were mostly selected from H. rhamnoides subsp. mongolica with a few of hybrid origin from H. rhamnoides subsp. mongolica and subspecies in Europe.