Genetic Diversity Of Three Species Of Ligularia (Asteraceae) In Eastern Of Qinghai-Tibet Plateau Of China

Ligularia sagitta, L virgaurea, and L. przewalskii are distributed over the east of Qinghai-Tibet Plateau. Among them, L. sagitta, L. virgaurea, which have behavior of clonal reproduction, are endangering the meadow more and more seriously, the model poisonous weeds in alpine meadow. In the research, the author, by means of random amplified polymorphic DNA (RAPD) technology, studies their genetic diversity, population genetic structure, in order to provide a scientific basis for preventing meadow form retrogradation. The main esults of this research are as follows.Three natural population of L przewalskii add up to 58 individual,with 17 random primersand 201 loci were detected .At species level, the percentage of polymorphic band (PPB ) was 59.20%, Ner s gene diversity (h) was 0.1460 and Shannon index (I) was 0.2321.At population level ,the means of the three indexes were 35.99%, 0.1081 and 0.1671 c AMOVA showed that 27.59% of the genetic diversity resulted form differentiation among population with remaining 72.41% residing within population.The coefficient of gene differentiation (Gtf) generated by POPGENE was 0.2669.Three natural population of L. sagitta, add up to 62 individual , with 17 random primers, 128 polymorphic loci. At species level, the percentage of polymorphic band (PPB ) was 63.68%, Nei' s gene diversity (h) was 0.1688 and Shannon index (I) was 0.2632.At population level ,the means of the there indexes were 42.45%,0.1271,0.1958o AMOVA showed that 22.87% of the genetic diversity resulted form differentiation among population with remaining 77.13% residing within population. The coefficient of gene differentiation (Gst) generated by POPGENE was 0.2400.Five natural population of L. virgaurea, add up to 100 individual , with 17 random primers, 132 polymorphic loci. At species level, the percentage of polymorphic band (PPB) was 65.67%, Nei's gene diversity (h) was 0.1465 and Shannon index (I) was 0.2307.At population level ,the means of the there indexes were 32.24%,0.0885,0.1384 . AMOVA showed that 37.03%t of the genetic diversity resulted form differentiation among population with remaining 62.97% residing within population. The coefficient of gene differentiation (Gst) generated by POPGENE was 0.3955.Under natural conditions, L. sagitta and L virgaurea "s rhizomes are suppressed due to other biological competitions in the meadow, therefore they mainly zoogamy. This fact reminds us : which protecting the meadow . In order to suppress spreading and enlargement of later population, should we in order to take effective measures to sexual reproductive organs; we also need to pay more attention to ecological recovery and species protection in the degenating meadow to prevent land form further desertification , make clonal growth of Ligularia suppress all the time and prevent their from occupying more extensive habitat.