Construction of core germplasm of Xinjiang wild walnut

Astract:【Objective】Deep characterization of genetic resources is a prerequisite for genetic improve-ment and management of walnut. Xinjiang wild walnut natural preservation in Gongliu county of XinjiangYili Kazak Autonomous Prefecture, has abundant wild walnut germplasm resources, and contains a largenumber of fine property genes. Construction of Xinjiang wild walnut core germplasms can be beneficial foreffective preservation and utrilization of the resources.【Methods】In the experiment, the seedling leaveswere collected for SRAP analysis from 4 217 wild walnut trees in the wild walnut valley of Gongliu county.Genetic diversity informations of Xinjiang wild walnut obtained by SRAP were used for clustering un-grouped scheme, using the ILDSS (optimizing LDSS) method to construct the primary core germplasms ofXinjiang wild walnut. Based on the basic data of the wild walnut trees in Xinjiang wild walnut germplasmresources database, we comprehensively analyzed the actual survey results to supplement the establishedprimary core germplasm, and finally determined the core germplasms of Xinjiang wild walnut. The aver-age effective allele number (Ne) , average Nei's genetic diversity (H) and the average Shannon informationindex (I) were selected as the genetic parameters to evaluate the genetic diversity of core germplasms inthis study.【Results】0.5% to 20% sampling proportion were selected from the Xinjiang wild walnut group, using LDSS (optimizing LDSS) method of clustering ungrouped scheme optimization for collecting 10 coresample set. Among the 10 core sample sets, only one had smaller values of Ne value, average Nei's genet-ic diversity index value and average Shannon's information index value than those of the original germ-plasm genetic parameters. The core samples genetic parameters and the determined sample numbers wereused to construct the primary core germplasm of the Xinjiang wild walnut. The result showed that primarycore germplasms accounted for 0.81% of the original germplasm, retention rate of the average Ne value, av-erage Nei's genetic diversity and average Shannon's information index of primary core germplasms were100.01%, 100.02% and 100.02% respectively. T-test results showed that, the average Ne value, averageNei's genetic diversity and average Shannon's information index of primary core germplasms were not sig-nificantly different from the original ones at 0.05 level of probability. The constructed primary core germ-plasms of Xinjiang wild walnut could well represent its original germplasm in this study. In order to makemore comprehensive and perfect Xinjiang wild walnut core germplasms, on the basis of the builded 34 pri-mary core germplasms, with reference to the Xinjiang wild walnut base database data such as fruit type, bark roughness, flowering order, branches colour, resistances to diseases (insects) , 14 additional sampleswith special properties were added. Finally, Xinjiang wild walnut core germplasm included 48 samples, which accounted for 1.14% of the original germplasms. The retention rates of the average effective numberof alleles, average Nei's genetic diversity index, and average shannon's information index accounted for99.99%, 99.92% and 99.98% of the original germplasms, respectively. T-test result showed that, at thelevel of 0.05, the three kinds genetic parameters were not significantly different from those of its originalgermplasms.【Conclusion】Construction of the Xinjiang wild walnut core germplasms were complementedby clustering ungrouped scheme and the constructed Xinjiang wild walnut core germplasms could wellpresent the original wild walnut resources genetically and ecologically. The experimental results can pro-vide some theoretical basis for the protection and utilization of this precious resource.