Construction of core germplasm of Xinjiang wild walnut

ZHANG Jie; ZHANG Ping; LI Qinxia

doi:10.13925/j.cnki.gsxb.20170342

Abstract：[Objective] Deep characterization of genetic resources is a prerequisite for genetic improvement and management of walnut.Xinjiang wild walnut natural preservation in Gongliu county of Xinjiang Yili Kazak Autonomous Prefecture,has abundant wild walnut germplasm resources,and contains a large number of fine property genes.Construction of Xinjiang wild walnut core germplasms can be beneficial for effective preservation and utrilization of the resources.[Methods] In the experiment,the seedling leaves were 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 ungrouped scheme,using the ILDSS (optimizing LDSS) method to construct the primary core germplasms of Xinjiang wild walnut.Based on the basic data of the wild walnut trees in Xinjiang wild walnut germplasm resources database,we comprehensively analyzed the actual survey results to supplement the established primary core germplasm,and finally determined the core germplasms of Xinjiang wild walnut.The average effective allele number (Ne),average Nei's genetic diversity (H) and the average Shannon information index (Ⅰ) were selected as the genetic parameters to evaluate the genetic diversity of core germplasms in this 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 l0 core sample set.Among the 10 core sample sets,only one had smaller values of Ne value,average Nei's genetic diversity index value and average Shannon's information index value than those of the original germplasm genetic parameters.The core samples genetic parameters and the determined sample numbers were used to construct the primary core germplasm of the Xinjiang wild walnut.The result showed that primary core germplasms accounted for 0.81％ of the original germplasm,retention rate of the average Ne value,average Nei's genetic diversity and average Shannon's information index of primary core germplasms were 100.01％,100.02％ and 100.02％ respectively.T-test results showed that,the average Ne value,average Nei's genetic diversity and average Shannon's information index of primary core germplasms were not significantly different from the original ones at 0.05 level of probability.The constructed primary core germplasms of Xinjiang wild walnut could well represent its original germplasm in this study.In order to make more comprehensive and perfect Xinjiang wild walnut core germplasms,on the basis of the builded 34 primary 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 samples with 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 number of alleles,average Nei's genetic diversity index,and average shannon's information index accounted for 99.99％,99.92％ and 99.98％ of the original germplasms,respectively.T-test result showed that,at the level of 0.05,the three kinds genetic parameters were not significantly different from those of its original germplasms.[Conclusion] Construction of the Xinjiang wild walnut core germplasms were complemented by clustering ungrouped scheme and the constructed Xinjiang wild walnut core germplasms could well present the original wild walnut resources genetically and ecologically.The experimental results can provide some theoretical basis for the protection and utilization of this precious resource.