Study On Genetic Diversity Of Germplasm Resources In Castanea Mollissima

Based on field investigations and analysis of the natural distribution of Castanea mollissima in P. R. China, 90 varieties of 9 populations of C.Mollissima (Beijing, Hebei, Shandong, Zhejiang, Shanxi, Hubei, Henan, Jiangsu, and Anhui) were selected and investigated. Genetic diversities were evaluated and compared at two levels of morphology(i.e., leaf and nut for 9 populations) and DNA fingerprint(AFLP analysis on 6 populations) . The study was undertaken to identify chestnut(Castanea mollissima) material of varieties in China by Amplified Fragment Length Polymorphism(AFLP) The main results as following:(1) Morphological diversities among/within populations were discussed by analyzing characters such as leaf and nut. Analysis of variance for all characteristics were significantly different among populations and among individuals within population. The mean phenotypic differentiation coefficient (Vst) shows that the variation within population (24.26%) is extremely higher than that among populations(75.74%) which revealed that variation within population were the more important. The nut becomes larger, the shape of the nut changes from spherical, and leaf shape of the longitude and latitude, upon increasing of the lonitude and latitude. The nut gets smaller as the altitude becomes higher. According to the correlation analysis, the populations of C.Mollissima investigated may be divided into two groups and four sub-groups.(2) The AFLP system was built and used for the amplification reaction in the experiment. There were totally 90 individuals were selected and analyzed by amplifications using 9 pairs of AFLP primers screened, 806 bands were obtained, 695 bands (86.23% ) of them were found to be polymorphic. The difference of frequency reflected the differences of genetic structure. The polymorphic bands and common bands showed variation diversity and genetic intercommunity of chestnut germplasm resources. As for C. Mollissima, genetic differentiation coefficient among 6 populations (Gst) is 0.4753. Genetic identities within the 6 populations were 0.0804 , this indicated that the genetic diversity of C. Mollissima were mainly existed within population at molecular level. According to the UPGMA cluster analysis.(3) To obtain AFLP markers in chestnut germplasm resources, the polymophic primers were used. It was found that 20 varieties had unique AFLP fingerprinting. The others could be identified by 2-3 bands. The similar coefficient of materials tested was 0.56. The UPGMA cluster based on AFLP wasundertaken and a total of 90 chestnut varieties were distinctly classified into 14 types. The genetic distance increased with the enhancing of geographic distance.(4)The diversity levels are different between pheuotype or DNA markers and the former was more sensitive to environment. Genetic cluster analysis is similar based on the results of phenotype and DNA markers which means the coincidence of this two methods applied for evaluating genetic diversity was better. The study is a meaningful approach for evaluating genetic diversity, sampling strategy, conservation and utilization of genetic resources of Castanea.