Analysis Of Genetic Diversity Of Hu Mulberry Germplasm And Primary Selection Core Collection Construction

The Hu mulberry of Taihu lake basin is the total name of native varieties and local varietyies in lower reaches of the Chang jiang river, taihu lake area and Jiangsu and Zhejiang province.It is an important component of our country mulberry germplasm resources, and they were widely cultivated in main silkworm rearing areas of our country. In the long-term cultivation process, it had been adapted to the local natural environment and also created unique botanical characteristics and biological properties through the natural selection and artificial cultivation.The same feature of Hu mulberry: Crown unfolded; branches are thick and long, erect, less collateral, there are lying branches, yellowish skin color; leaf base is heart-shaped, large and whole leaf with sharp tip ,less fruit.This paper carried out genetic diversity of research about Hu mulberry germplasm resources and constructed the primary core collection, by the use of ISSR molecular markers. It had a practical value and theoretical significance to Hu mulberry of our country in the molecular identification, genetic improvement, molecular-assisted breeding, gene mapping and protection of the important agronomic traits.The main contents of this paper were summarized as the following:1.Genetic diversity of Hu mulberry germplasmBy the use of ISSR markers, the study carried out the genetic diversity analysis of the 141 varieties of Hu mulberry. By PopGene 32 software, it caculated the genetic similarity coefficient of the 141 varieties of Hu mulberry germplasm and made a cluster analysis by UPGMA.By using 12 specific and stable primers, a total of 90 bands were amplified, with 57 polymorphic bands, that is about 89.15% of which. Genetic similarity coefficient were changed from 0.6333～1.0000.Observed number of alleles(NA),effective number of alleles(NE),Nei's gene diversity(H),Shannon's information index(I) was 1.6333,1.4163.0.2360.0.3482 respectively. This result indicated that there were the large ISSR variation and high polymorphism among the 141 Hu mulberry germplasm. Clustering results showed that the Hu mulberry varieties could be divided into distinct categories and four 4 sub-categories.2.Constructing the Primary Core Collection of Hu mulberry.By using stepwise clustering and random methods and the modified heuristic algorithm to construct primary core collection of 141 Hu mulberry Germplasm resources respectively, it contained 46 and 41 primary core collections of Hu mulberry and the ratio of the primary core collection samples were 32.62%,29.08% respectively. By use of statistical software SPSS13.0 and combining with molecular markers polymorphic loci, percentage of polymorphic loci, observed number of alleles, effective number of alleles, Nei's genetic diversity index and Shannon's information index to analyse and do test of two groups primary core collection, the results showed that the 46 and the 41 primary core collections of Hu mulberry could conserve the genetic diversities and structures of the primary collection better, but the 41 core collections was superior to the 41 primary core collections. Finally, the 41 primary core collections were identified as the primary core collction of Hu mulberry germplasm.