濒危植物华山新麦草(Psathyrostachys huashanica)的遗传多样性及其保护

筛选的12条ISSR引物，对采集于陕西华山3个自然居群、20个亚居群的150个华山新麦草(Psathyrostachys huashanica Keng ex Guo)个体的遗传多样性进行了分析．发现华山新麦草样本ISSR产物的多态位点比率(P)为96．8％；每个位点的平均有效等位基因数(Ae)为1．411；居群的预期杂合度(He)为0．251，大于一般风媒异交植物的平均值0．148；居群的香农多样性指数(I)为0．391；这些结果表明华山新麦草在居群水平上有相对较高的遗传多样性．亚居群间的基因分化系数(GST)为0．304，表明大部分(约为70％)的遗传变异均存在于亚居群内．同时亚居群间具有一定频率的基因流，其遗传相似性也较高，变化范围为0．796～0．974(平均为0．903)．根据上述结果推断，华山新麦草的濒危不是因为遗传多样性稀有，而是由于它对特殊生态环境的要求影响了它的扩散而仅分布于华山这一狭小范围．因此，只要能够保证目前华山的生态环境不被进一步破坏，华山新麦草就能得到很好的保护而不会因种内遗传多样性降低而灭绝．

Genetic Diversity of the Endangered Species Psathyrostachys huashanicain China and Its Strategic Conservation

In order to estimate genetic diversity of Chinese endangered grass species Psathyrostachys huashanica Keng ex Guo, 12 selected ISSR primers were used to analyze genetic variation of 150 individuals from 20 sub-populations collected in Huashan Mountain in Shaanxi Province. The results indicated that percentage of polymorphic loci ( P ) was 96.8%, and the average effective number of alleles ( Ae ) was 1.411 per locus. The mean expected heterozygosity ( He ) of the total population was 0.251, which was greater than the average value (0.148) of the wind-pollinated and outcrossing plant species. Shannon index of the total population was 0.391, suggesting relatively high genetic diversity in P. huashanica . The genetic differentiation coefficient ( G (ST )) was 0.304,proposing that most (ca. 70%)of the genetic variation occurred within sub-populations with a certain frequency of gene flow. The sub-populations demonstrated relatively high genetic identity with similarity coefficient varying between 0.796-0.974 (0.903 on average). It is concluded based on the study that the main threat to the existence of P. huashanica is ont associated with the low level of genetic diversity, instead, the survival of this species is significantly related to its unique environmental requirements. The authors suggest that the continued availability of P.huashanica could be preserved if its original ecological habitats could be maintained and restored.