Analisis Of Genetic Diversity And Establishment Of Core Collection Of Walnut Varieties With AFLP Markers

Walnut has high economic value which originated in China and has been cultivated for a long time in China. Gremplasm resources of walnut is abundant. Inder to provide scientific basis for the identification,conservation and utilization of walnut germplasm, the paper used AFLP markers to analyze their genetic relationship and the genetic diversity of 131cultivars of walnut. Then core collection of walnut was developed based on the AFLP marker and morphological data. The genetic relationship of different species of walnut was studied.The results were as follows:1 .The genomic DNA of walnut was extracted by a modified CTAB method. The modified isolation buffer was: 100 mmol/L Tris-HCl (pH 8.0). 20 mmol/L EDTA, 1.4 mol/L NaCl, 2% CTAB, 2% PVP₄₀, 100 mmol/L β -Mercaptoethanal and 10 mmol/L Na₂S₂O₅.The RNA was eliminated from the solution with RNase.and the DNA was purified by phenol/chloroform (one), chloroform/isoamyl alcohol (twice). The purified walnut genomic DNA was suitable for AFLP analysis, by phenol/chloroform.2.Twenty EcoRI/MseI primer pairs selected out from 126 primer combinations were used for in this study, based on level of polymorphisms and the number of strong bands. 1643 bands were scored, 92.03% of which (1512 ) were polymorphic. The rates of polymorphic band varied among 131 walnut cultivars.3.Eight EcoRI/Msel primer pairs from twenty showing high level of polymorphism and scorable strong band were used for the practical AFLP analysis of different species of walnut. 833 bands were scored,98.32% of which (1512 ) were polymorphic .The rate of polymorphism were different in eight species of walnut.4.The fingerprinting of 131 assayed materials was established based on AFLP bands created by using 20 primer combinations. These materials could be distinguished, and some genotypes had their unique banding patterns, which could be used to identify these accessions.5.The core collection of assayed persimmon cultivars was constructed using the method of sampling progressively by cluster grouping based on AFLP data, andusing the percentage of polymorphic bands as the main index combined with the morphological index and origin.6.Eight walnut species were individed into four groupst/.nigra L., J.Cathayensis Dode, J.sieboldiana Max. and J.cordiformis Max., J.sigillata Dode, J.hopeiensis Hu and J.manshurica Max., J.regia L. though analysed polymorphism of different walnut species.