Construction of DNA Fingerprints of Good Walnut Varieties and Clones
As an important economic and oilseed tree species in China,the number of good varieties and clones of walnut continues to increase with the deepening development of its breeding.However,the frequent interspecific and intraspecific crosses and the wide circulation of asexually propagated scions make it difficult to effectively classify and discriminate different varieties and clones in terms of phenotypic traits.In this study,the SSR molecular marker technology was used to construct DNA fingerprints of 100 ex-cellent cultivars and clones of walnut,providing theoretical and technical supports for the accurate and efficient evaluation,identifi-cation,protection and utilization of walnut germplasm resources.The young leaves of 100 fine varieties and clones of walnut were collected and the total genomic DNA was extracted by CTAB method.Eighty-seven pairs of published SSR primers for walnut were screened,and the screened SSR primers with good polymorphisms were used to analyze the genetic diversity of the 100 good walnut varieties and clones and to construct DNA fingerprints.Eleven pairs of stable and well polymorphic SSR primers were screened.The total number of bands amplified by per pair of primers ranged from 45 to 84,with an average of 62 fragments amplified from each SSR locus.The polymorphic band ratio ranged from 91％to 100％,with an average of 98％.The number of effective alleles ranged from 1.119 to 1.415,with a mean value of 1.297.The variation trends of Nei's genetic diversity index(H)and Shannon's informa-tion index(I)of all primers were consistent,and the mean values were 0.191 and 0.313,respectively.The polymorphism informa-tion content(PIC)ranged from 0.275 to 0.704,with a mean value of 0.519,in which eight loci(JH89978,JR3773,JR1165,JM78331,JM68820,JR6439,WGA-89 and WGA-321)showed high polymorphism(PIC＞0.5).The results of adjacency cluster-ing showed that 100 walnut samples were grouped into 3 categories.The differentiation rate of each primer on the test walnut samples ranged from 68％(JM78331)to 100％(JR4964 and WGA-321),and the primer WGA-321,with a high differentiation rate and PIC value(0.704),was selected to successfully construct DNA molecular fingerprints of 100 good walnut varieties and asexual lines.The results provided a theoretical basis for walnut variety identification,seedling purity testing,and variety tracing.
万方数据
维普
