明党参的遗传多样性研究

Studies on genetic diversity in Changium smyrnioides Wolff(Umbelliferae)

对珍稀特有单种属植物明党参的 4个居群的材料 ,从物种生物学及保护生物学的角度 ,对它们的遗传多样性进行了研究和分析。研究结果表明 :各居群染色体数目恒定 ( 2n =2 0 ) ,核型类型均为 2A型 ,居群间存在核型多型性 ,主要表现为染色体的杂合性及随体染色体的位置也有一定变化。采用淀粉凝胶电泳方法 ,分析了 1 0个酶系统 ,获得 1 9个基因位点的资料 ,分析结果表明 :居群的遗传变异处于较低水平 ,多态性位点比率P =33.35% ,等位基因平均数A =1 .43,等位酶基因多样度指数Ho=0 .0 3,He=0 .0 7。总的基因位点变异中 ,有 58%的变异来自于居群间 ,42 %的变异存在于居群内 ,居群杂合体过量的位点仅为 1 3%。偏东部居群的遗传多态性比西南部居群高。根据明党参居群遗传变异式样并结合相关研究 ,提出了其遗传多样性保护策略。

WT5BZ]Changium smyrnioides Wolff is an endangered species of the monotypic genus Changium (Umbelliferae). For a better understanding of its genetic diversity, four populations of this species were cytologically and allozymically investigated. The karyotypic analysis of C. smyrnioides indicated that the chromosomal number was stable (2n=20) in all populations. Karyotypes of the populations were all “2A” type. Karyotypical polymorphism was shown as the chromosomal heterozygosity, and position shift of the satellite. Genetic diversity of 4 populations was analysed with starch gel electrophoresis. A low level of allozymic diversity was estimated based on 19 loci of 10 enzyme systems. Genetic diversity within 4 populations was relatively low with the proportion of polymorphic loci (P) ranging from 19% to 42.9%, average number of alleles per locus (A) from 1.2 to 1.7, mean expected heterozygosity (H e) 0.073 and mean observed heterozygosity (H o) of 0.030. In general, about 58% of genetic variation were attributed to the differentiation among populations, while the remaining 42% resided within populations. The genetic diversity of the eastern populations was higher than that of the southwestern populations. On the basis of this studies, we thought that the habitat of C.smyrnioides should be protected and most of the populations should be sampled so as to retain as much genetic diversity as possible in ex situ conversation. [WT5HZ]