中国特有种四合木种群遗传多样性的RAPD分析

采用随机扩增多态性 DNA(RAPD)技术检测了西鄂尔多斯高原特有种四合木种群 5个斑块的遗传多样性。2 2个扩增引物产生 1 1 6条带 ,Shannon信息指数和 Nei指数对 RAPD数据的分析表明 :四合木种群存在较高的遗传多样性 ,其中千里山斑块的遗传多样性和多态位点比例较高 ,石嘴山斑块的最低。遗传多样性的 86.5 %存在于斑块内 ,斑块间的遗传变异为 1 3 .5 %。遗传距离与地理距离无直接相关关系。这些结果说明 ,遗传多样性反映了四合木种群基因组 DNA存在较高的变异性 ;同时各斑块间存在一定的基因流 ,四合木各斑块可看成是处于同一种群的半隔离状态 (meta-种群 ) ,对四合木应注意保护遗传多样性丰富的 meta-种群。

An Analysis of the Genetic Diversity of Populations Endemic Species Tetraena mongolica Maxim. (Zygophyllaceae) by RAPD in ORDS Plateau, China

Tetraena mongolica Maxim., a monotypic genus of Zygophyllaceae endemic to China, it is an ancient relic shrub and second\|class conserved plant in nation. T.mongolica grows in semi\|arid and arid regions of western ORDS plateau, where T.mongolica plays an important role in soil conservation. However, T.mongolica is affected by a variety of factors.Its distribution is being continually reduced. Its regeneration is difficult and it is increasingly endangered. Random amplified polymorphic DNA(RAPD markers) provides a powerful tool for investigation of genetic variation in natural and domesticated populations. We described the five patches genetic variation of RAPD markers in natural, diploid sources of T.mongolica. This is the first molecular level report of it. Twenty\|two arbitrary 10 base pair primers produced 116 amplification bands. Based on the presence/absence bands, Shannon's index, Nei's index and a genetic distance matrix were analyzed. The results showed that higher genetic diversity existed within T.mongolica populations. The Qianlishan patch had higher level of genetic diversity and polymorphic loci proportion, while the Shizuishan patch had the lowest level. The average proportion polymorphic loci of T.mongolica was higher than other rare and endemic species. Genetic diversity of Shannon's index varied larger with the primers than with the patches. Wujiamiao patch was the highest Shannon diversity(2 617) and Shizuishan patch was the lowest one(2 214). Nei gene diversity index was generally congruent with Shannon index. Gene diversity of Wujiamiao patch was the highest(0 344) and Shizuishan was the lowest(0 288) of all the assayed primers. Genetic variation among patches was 13 5% of total genetic diversity and 86 5% of genetic diversity existed within patches. Genetic distance was also calculated. Genetic distance between Qianlishan, Shizuishan patch and Wujiamiao patch were 0 143 and 0 152 respectively, which were the longest. Genetic distance did not directly correspond to geographic distance. Genetic diversity was related to higher variability of gemonic DNA of T.mongolica population and the higher variability was advantageous to tackle the change and choice of habitat. It was one of the reasons that T.mongolica became the constructive species of the area. Some degree gene flow existed in T.mongolica patches. It was considered to be meta\|population. Meta\|populations of higher genetic diversity should be conserved.