新疆核桃8个天然群体遗传多样性的SSR评价

【目的】为进一步建立新疆核桃种质资源的分子指纹鉴定体系奠定基础,为制定新疆核桃资源的有效保育和利用策略提供科学依据,并为深入研究新疆栽培与野生核桃资源间的系统关系提供实验数据。【方法】应用12对稳定、适用性好的SSR引物对新疆南北疆核桃的8个栽培及野生群体的230份样品进行扩增,研究其遗传多样性。【结果】12对SSR标记揭示了新疆核桃丰富的遗传多样性:等位基因93个,平均多态性带比率96.77%,平均Nei多样性指数(H)0.3151,平均Shannon多样性指数(I)0.382 0。8个新疆核桃群体的变异主要来源于群体内,群体间分化较小,遗传分化系数仅为0.172 0。估测的群体间基因流(Nm)为1.712 6,表明新疆8个核桃群体之间存在适度的基因交流,种子的传播或人为实生选种以及杂交育种可能是基因交流的主要原因。对新疆核桃8个群体的Nei多样性指数(H)与Shannon多样性指数(I)及多态位点百分比进行分析,表明和田实生核桃的遗传多样性最高,伊犁霍城野生核桃的遗传多样性最低。采用UPGMA方法进行供试核桃的遗传距离聚类分析,8个群体被聚为两大类:和田、叶城及温宿等3个群体聚为一大类;而巩留、霍城、吐鲁番、哈密、鄯善等5个群体聚为另一大类,Mantel检测与UPGMA聚类均表明群体间的遗传距离与群体的地理距离之间具有较高的相关性。【结论】新疆核桃有着较高的遗传多样性水平,同时揭示了新疆核桃属植物的遗传变异、群体扩散及其地理系统发育进化等方面的规律,在此基础上,认为在进行遗传多样性保护和种质资源的保存时,应充分重视群体内不同类型个体的保存,同时也要在分布区不同区域内保存不同的群体。

Analysis of Genetic Diversity of Eight Natural Walnut Populations by Using SSR Marker in Xinjiang,China

Objective]This study aims to provide a benchmark reference for establishing molecular identification system and for further use in breeding program conservation strategy of Cermplasm resources of walnut,and also supplement useful information for understanding the relationship between walnut cultivars and wild species.Method]Twelve black walnuts simple sequence repeat(SSR) primer pairs were used to study 230 samples of walnuts native to seven populations in Xinjiang in order to analyze their genetic diversities. Result]A relatively high level of genetic diversity was detected in germplasm resources of Xinjiang walnuts with 12 polymorphic microsatellite loci.A moderate level of genetic diversity was observed at population level by the total 93 of alleles.The average percentage of polymorphic bands in all primers was 96.77%,the average expected heterozygosity was 0.315 1,and average Shannon information index was 0.382 0.The parameters - Genetic differentiation coefficient and gene flow of population genetic structure in walnut were analyzed in this study.Genetic differentiation coefficient {Gst =0.172 0) for seven walnut groups showed that genetic variation was mainly within the groups and accounted for 82.11%of total variations.The gene flow (Nm = 1.712 6) according to the genetic differentiation coefficient between groups indicated that there were partly gene exchanges among walnut populations.It is suggested that the main way of gene exchanges could be seed spreading and human introduction of occasional seedling and cross breeding.The expected heterozygosity and Shannon information index and percentage of polymorphic loci of the seven populations were analyzed and the results reflected that the genetic diversity of Hetian population was the highest and that of Huocheng population was the lowest.Juglans regia L.could be clustered into two groups with UPGMA method.In one group,Hetian walnut population clustered together with Yecheng walnut and Wensu walnut.In the dendrogram,In other group,Gongliu,Huocheng,Tulufan,Hami and Shanshan clustered in the same group. Mantel test and UPGMA dendrogram based Nei 's genetic distance showed that genetic distance among populations had more significant correlation with geographic distance.Conclusion]It was indicated that germplasm resources of Xinjiang walnuts remained with a relatively high level of genetic diversity.The results should be of great importance for further understanding of population genetic structure,population spreading and phylogeography in germplasm resources of Xinjiang walnuts.On the basis of the study of population genetic structure and the highest genetic diversity,baseline data was provided for the conservation and management of these species.The distinguished type individual should be given a high priority consideration in germplasm resources of Xinjiang walnut population s in situ germplasm conservation.Concurrently,different population should receive the same conservation.