Assessment of genetic diversity among six populations of Rhododendron triflorum in Tibet using ISSR and AFLP markers

Abstract

In order to assess genetic variations among Rhodendron trifolium populations sampled from Tibet and determine the correlation among genetic variations, the geographic location of a population, and factors that influence high-level genetic diversity, in total of 107 R. triflorum samples using inter simple sequence repeats (ISSR) and amplified fragment length polymorphisms (AFLP). All genotypes were collected from six different areas. Eleven ISSR primers and five AFLP primer pairs were screened, and 118 and 169 amplification products were produced, of which, 96.61% in ISSR and 95.27% in AFLP were polymorphic. High genetic diversity was observed at the species level: Nei's genetic diversity (H) was 0.3382 and 0.306, and Shannon's information index (I) was 0.5085 and 0.4642 in ISSR and AFLP, respectively. Both the coefficient of gene differentiation (GST 0.3752 in ISSR, 0.31 in AFLP) and AMOVA analysis (75% in ISSR, 71% in AFLP) indicated that most genetic diversity was distributed within populations. Gene flow (Nm) was 0.8326 in ISSR and 1.1127 in AFLP. The analyze of unbiased genetic distances determined by an unweighted pair group method using arithmetic mean (UPGMA) phonograms indicated that there was a certain degree correlation between the genetic distance and the geographic distance, which was confirmed by a principal coordinate analysis. The results maybe indicated that difference of geographical environment and variation of habitat types caused the genetic differentiation of R. triflorum. At last, some conservation strategies for R. triflorum germplasm were put forward according to these results.