Study On Develop Of EST-SSR Primer And Genetic Structure Of Tamarix Chinensis

In this paper genetic diversity and population genetic structure of 6 natural populations of Tamarix chinensis, were studied by means of simple sequence repeats DNA (EST-SSR) markers. Based on the research of population genetic structure strategies, the conservation of these germplasm resources of T.chinensis were also discussed. The main results are highlighted in the following:546 simple sequence repeats (SSRs) from 22713 T. chinensis expressed sequence tags (ESTs) were identified and characterized. Dinucleotide repeats and trinucleotide repeats accounted for 30.9% and 31.6% of the total EST-SSRs,respectively. 75 of these potential EST-SSRs were selected for primer design. Of these 75 primer pairs, 40 were monomorphic17 were co-dominant and polymorphic on average,(A)were 7.1765,(Ne)were 4.7267,(He)was 0.4713,(h)was 0.4560,(I)was 1.7760.According to the genetic diversity of filial generation stands,the ranking among them was the CY population > the HK population > the LJ population > the KL population > the DM population > the ST population. The difference of Genetic diversity are small among the first five populations.only ST population are lower. Perhaps the main cause is forest plantations that originated.Coefficient of genetic differentiation was 0.0804 on average and the majority of genetic variation occurred within populations. The population genetic differentiation reached a moderate level in forest.we found some specific alleles in one population only. It showed that: there are some differentiation among six populations to a certain extend.The alletes of primer Estssr-15 are rich.we can took only one primer(Estssr-15) to distinguish the DM population, ST population and four populations from Shandong province.At the population level, the average of observed heterozygosity (Ho) was 0.5364, much lower than expected heterozygosity (He=0.4835). This shows that heterozygote are excessive and and significant deviations from Hardy-Weinberg equilibrium to be shown by test.It related to sampling superior plants only. Subdivision, distribute in a row and high density of population might lead to the deficiency of heterozygotes and excess of homozygotes.The genetic variation occurred within populations and correlated positively with geographical distance. We should protect different types of individuals in large population and the point is the populations in natural distribute centre.we should preserve genetic resources of different regions and move to other places. In the use of T chinensis: we should use variation within specie and create new variations by cross between species.