Primary study on genetic divergence within populations of Heptacodium miconioides.

Random amplified polymorphic DNA (RAPD) analysis was applied to the samples of Heptacodium miconioides from 9 main populations(No.1: Jiuquxi in Dapanshan, No.2: Huaxi in Dapanshan, No.3: Chachangshang in Dongbaishan, No.4: Beishan, No.5:Botanic Garden in Zhejiang Normal Univ., No.6: Chachangxia in Dongbaishan, No.7: Tiantaishan, No.8: Kuocngshan, No.9: Simingshan). Twenty seven primers screened from 70 ones yielded 268 RAPD bands which had 163 polymorphic products and a total band rate of 60.7%. The Jaccard coefficient was applied to compare the genetic similarity of these 9 populations based on the RAPD data. A dendrogram based on Jaccard coefficients was constructed by using the between-groups linkage method. The dendrogram shows that these 9 populations are clustered into three groups: No.1, No.2, No.3, No.4, No.5 and No.6 populations together; No.7 and No.8 populations in the second cluster; the SMS population(No.9) alone in the last cluster. The dendrogram result is also supported by a principal component analysis(PCA) of RAPD phenotypic data. The analysis indicates that the genetic variations within the nine populations are correlated with their geographical distance. Finally, the authors propose two approaches of conserving genetic diversity of H. miconioides populations in fragmented habitats based on its genetic structure and its biological characteristics.