Assessment of Genetic Variation and Distribution Pattern of Thalictrum petaloideum Detected by RAPDs

Abstract: Random amplified polymorphic DNA (RAPD) method was applied to assess genetic variation and population structure of Thalictrum petaloideum L. (Ranunculaceae). Two hundred and forty-six individuals from 11 populations of the species were investigated by RAPD profiles. Twenty selected RAPD primers generated 125 bands, in which 120 were polymorphic. The results revealed a high level of genetic variation (percentage of polymorphic bands (PPB) was 96%, Nei’s gene diversity (h) was 0.350 2 and shannon’s information index (I) was 0.519 9 at the species level). The differentiation among the populations was high (GST = 0.351 1) in this species. Result of analyzing of molecular variance (AMOVA) showed that 38.88 % of genetic variance was found among the populations. Positive correlation with r = 0.194 5 (P = 0.000 2) was found between genetic distance and geographic distance among populations. Two populations distributed in the drainage basin of Yangtz River affined genetically and formed one clade and the rest nine populations formed the other clade in both unweighted pair-group method using arithmetic average (UPGMA) trees made by two different methods. It was very clear that these two populations were very special, and must be closely related in history, despite the fact that they now share quite weak link to the rest populations through gene communication. Key words: Thalictrum petaloideum; random amplified polymorphic DNA (RAPD); genetic diversity