Assessment Of Genetic Diversity And Population Genetic Structure In Chinese Stipa Breviflora Using SSR Markers

Belonging to Stipa L. of Gramineaa, Stipa breviflora is xeromorphic perennial bunchgrass, one of the main dominant species in Warm desert steppe. S. breviflora in China showed a continuous zonal distribution, which is suit the research on genetic diversity and genetic structure of populations, enrich grassland plants genetic diversity awareness; On the other hand, this study will also help the protection and reasonable utilization of S. breviflora grassland in practice.In this research, genetic diversity, population structure and genetic differentiation of 11 populations of S. breviflora were analyzed using SSR DNA markers. The results are as follows:(1) The best reaction system of SSR-PCR to S. breviflora was established as follows(25μL):100ng template DNA 1μl,2.0mmol/L Mg2+ 2.5μL, 100umol/L dNTPs 2μL,2.0U Taq DNA polymerase 0.5μL,0.2μmol/L each primer 1μL, make up the rest with ddH2O. PCR amplification program of better repeatability and stability was set up after a pre-degeneration 3 min at 94℃; degeneration 30s at 94℃; annealing time 30s, annealing temperature corresponds to each primer; extension 30s at 72℃; 30 cycle from degeneration to extension in total; then extension 10min at 72℃ finally conserved at 4℃.7 pairs of S.breviflora SSR primers with good amplification were screened out.(2)Seven SSR markers were used for analyses, a total of 19 alleles were detected and 2.71 alleles was detected on average per locus with the range of 2-4; The average number of alleles per population was 2.08. The average observed and expected heterozygosity were 0.35 and 0.72, respectively. The average polymorphism infermation content was 0.40 and the average Shannon information index was 0.56, the average gene flow was 3.15. Overall, the genetic diversity of S. breviflora is abundant, the genetic differentiation is low, the frequent gene flow presence between most populations. Genetic differentiation caused by genetic drift may not exist.(3)Further analysis showed that,71.19% genetic variation was from individuals. There was not a significant correlation between geographic distances and genetic distances among pairwise populations. The result of clustering using different methods is all individuals can be divided into three groups, genetic variation was from within groups. So, the main factors affecting the genetic structure of S. breviflora is geographic isolation.