基于ISSR分子标记的孑遗濒危植物四合木遗传结构分析

为阐明中国西北干旱区单属种孑遗濒危植物四合木(Tetraena mongolica)种群间的遗传分化和基因流。利用6个不同地理分布的四合木种群作为试验材料,从30条UBC引物中筛选出6条引物,并且对ISSR扩增反应体系和扩增程序进行了合理的优化,6个引物扩增出370个条带,多态性条带占71%。分析结果如下:①Nei’s基因多样性指数(He)为0. 316 8,Shannon’s多态性信息指数(I)为0. 458 6。表明四合木在不同种源间的遗传多样性水平差异较小;②群体多态性位点百分率在70. 00%~83. 33%,Nei’s基因多样性指数范围0. 286 5~0. 350 8,Shannon’s多态性信息指数在0. 423 6~0. 504 9。6个群体间的遗传分化系数Gst为0. 125 3,表明群体间具有一定程度的遗传分化;③6个种群的基因流(Nm)为3. 491 5>1,说明6个种群间存在一定的基因流,可以防止遗传漂变引起的遗传分化;④通过聚类分析,将6个不同地理种群的四合木分为3类,千里沟种群、伊克布拉格种群和巴拉贡种群先聚成第一大类,再与磴口—桃司兔种群聚成第二大类,而四合木自然保护区种群和甘德尔山种群则组成第大三类,这说明距离因素是影响四合木种群间遗传分化的主要原因,但不同生境条件也对四合木种群的遗传分化产生了影响。

Genetic Diversity of Plant Tetraena mongolica by ISSR Markers

Tetraena mongolica is an endangered plant belonging to a single genus,known as the‘plant giant panda’. It has been included in the first batch of national rare and endangered plant red papers. It is a special shrub endemic to the west of Ordos Plateau and its distributed area is small. Six different geographical populations of T. mongolica were used as test materials. Six of the 30 UBC primers were screened for the most suitable primers,and the ISSR amplification reaction system and amplification procedure were reasonably optimized. The 370 bands were amplified from the primers,and 71% of T. mongolica was polymorphic bands.The results of the analysis can be shown as follows:(1) The Nei’s gene diversity index was 0. 316 8 and Shannon’s polymorphism information index was 0. 458 6. The genetic diversity levels of T. mongolica different provenances were little different;(2)The percentage of groups polymorphism allele in the population ranged from70. 00%-83. 33%,the Nei’s genetic diversity index was 0. 286 5-0. 350 8,and the Shannon’s polymorphism information index was 0. 423 6-0. 504 9. The G st of genetic differentiation coefficient between the six populations was 0. 125 3,the results explain that there is a certain degree of genetic differentiation among populations;(3)The gene flow of the six populations was 3. 491 5>1,indicating that there was a certain gene flow among the six populations,which could prevent the genetic differentiation caused by genetic drift;(4)Cluster analysis was used to classify the tetrahedrons of six different geographic populations into three groups.The populations of Qianligou,Yikebulage,and Balagong clustered into the first category,and then they were clustered with the Dengkou-taositu rabbits into the second category. There are two major categories,and the population of Natural Reserve of T. mongolica and the population Gandle Mountain constituted the third largest category. This shows that distance factors are the main factors that affect genetic differentiation among T. mongolica populations,but different habits conditions also have an impact on the genetic differentiation of T. mongolica populations.