The Study Of Genetic Diversity And Clonal Structure Of Two Clonal Plants In The East Of Qinghai-Tibet Plateau Of China

Polygonum viviparum and Potentilla anserine are two clonal plants, which are widely distributed in the east of Qinghai-Tibet Plateau. Both the plants have clonal reproduction and seed reproduction, differing in depended on the rhizome under ground and bulbils for Polygonum viviparum and stolons for Potentilla anserine in clonal reproduction.Polygonum viviparum is distributed widely from temperature tone to arctic ocean, from American, Europe with low altitude to Qinghai -Tibet plateau of China and Himalayas. Potentilla anserine is also distributed widely in China and is a kind of pastures. Potentilla anserine have vigorous capacity of using different environment, so it has became one of dominant species in the degenerating meadow. The genetic diversity, clonal structure and relation to the altitude among seven populations of Potentilla viviparum and six populations of Potentilla anserine were analyzed by random amplified polymorphic DNA (RAPD) technique. The results suggest that progenitive character and distribution of clonal plant, and providing the foundation for studying mechanism of grassland deterioration, resume and regenerate it.13 random primers were selected out for the amplification of Polygonum viviparum and 117 repetitive loci with 84 polymorphic loci were generated. The total average percentage of polymorphic loci (PPL)was 71.79%, while that of population was only 32.60%. Meanwhile, we could also differentiate 43 RAPD genotypes among the 140 plants sampled from 7 populations. The mean of Simpson's index D was 0.639, and the mean of PD was 0.307, indicating that it was higher slightly than the mean of Ellstrand etal. (D=0.62, PD=0.17) .The genetic diversity of Polygonum viviparum was higher with an average Nei's gene diversity of 0.2891 and that of the Shannon's information index of 0.4207. In contrast, the genetic diversity within each population was low, with an average Nei's gene diversity of 0.1227 and an average Shannon's information index 0.1804. That the gene flow estimated by G_ST was only 0.3691, indicating low exchange among populations of Polygonum viviparum. Bayesian approaches showed the estimate forθ^B was 0.6023 and its 95% credible interval is [0.5539, 0.6454]. The G_ST values estimated by Nei index are 0.5753, very close to theθ^B estimate. AMOVA also demonstrated 66.59% of genetic variance among population, 33.41% of that within populations. The correlation analysis showed that the genetic diversity and clonal diversity within populations was not significantly related with the altitude.13 random primers were selected out for the amplification of Potentilla anserine and 132 repetitive loci with 117 polymorphic loci were produced. Total PPL was 88.64%, while that of population was only 49.12%. We could also differentiate 68 RAPD genotypes among 120 plants. The clonal diversity was high in the populations, the mean of Simpson's index D was 0.875, PD was 0.567. The genetic diversity of Potentilla anserine was high, with an average Nei's gene diversity of 0.3180 and an average Shannon's information index of 0.4732. In contrast, the genetic diversity within each population was low, with an average Nei's gene diversity of 0.1663 and an average Shannon's information index 0.2491. Bayesian approaches showed the estimate forθ^B was 0.4908 and its 95% credible interval is [0.4522, 0.5293]. The G_ST values estimated by Nei index are 0.4770, very close to theθ^B estimate, indicating less differentiation between populations than within populations. In addition, less gene exchange between populations (Nm—0.5482) was detected. AMOVA also demonstrated that genetic variance 49.18% existing within population, 50.82% among populations. The correlation analysis showed that the genetic diversity clonal diversity within populations was not significantly related with the altitude. However, the genetic diversity within populations was significantly positively related with the coverage (r= 0.8630).Clonal organ of two plant is different, but genetic diversity of populations is high, and populations are polyclonal. Because embryonal development and few megaspores were observed, Polygonum viviparum has hardly seed reproduction. However, this study results indicate Polygonum viviparum distributed in the east of Qinghai-Tibet Plateau have a little sexual reproduction, and the ratio of asexual and sexual reproduction need be studied further. High genetic variation of Potentilla anserine possibly related seed recruitment. Plant adjust reproduction strategy timely according to their habitat, which is dependent grow rule of plant. The analysis of clonal structure demonstrated that the mosaic among two clonal plant clones was clear, suggesting that this is probably because of their clonal architecture. Polygonum viviparum is transitional type between guerilla and phalanx and Potentilla anserine is guerilla clonal structure. This confirmed different clones (genotypes) have different growth potential, fitness and competition.Alpine meadow grassland is widely distributed in the central-eastern part of the Qinghai-Tibet Plateau and its surrounding mountain region, where the pasture is well on quantity. In recently years, the source are present the problem of ecology environment on vegetation degrading, land desertification process expanding rapidly and wetland ecology degrading. From light grazing to over-grazing, the dominant shrub and graminoid species were replaced by typical forbs and the index of rangeland quality decreased. Long-term heavy grazing plays an important role on alpine rangeland degradation in Qinghai-Tibet Plateau. Potentilla anserine is capable of expand grow range rapidly by clonal organ (stolons) and becomed the dominant species of Kobresia humilis meadow. For the future, we need to study reproduction strategy of clonal weed further and provide the foundation for studying mechanism of grassland deterioration, resume and regenerate it.