| Walnut(Juglans regia)belongs to the Juglandaceae.It is a temperate deciduous tree that uses wind-borne pollination as a pollination method.In china,the breeding history of walnut planting for nearly a thousand years and has now become the third largest walnut producer in the world.To detect the genetic diversity,genetic structure and genetic relationship of walnut germplasm resources in different regions,and provide theoretical basis for the protection,genetic improvement and utilization of walnut germplasm resources.In this study,18 pairs of EST-SSR primers were used to analyze the genetic diversity of 171 walnut germplasm resources samples(a superior line,b cultivated variety,c farm variety),including 116 walnuts from 25 regions(J.regia)germplasm resources samples and 55 Juglans sigillata germplasm resources samples collected from 5 regions,a indicates that superior line walnut germplasm resources,c indicates that farming varieties.The main results of the research are:1.Genetic diversity of walnut and J.sigillata resources:Among the walnut and walnut germplasm resources we collected,Hebei Fuping walnut germplasm resources(FP,Na=0.889,H_O=0.056)and Guizhou Heguo walnut germplasm resources(SWZ,Na=1.111,H_O=0.167)have low genetic diversity and high homozygosity.On the contrary,the Sichuan Chengdu walnut germplasm resources(CD,Na=1.278,H_O=0.333)and the Guizhou Academy of Forestry Walnut germplasm resources(YJS,Na=2.111,H_O=0.191)have high genetic diversity and heterozygosity.The value of genetic diversity of the different germplasm resources of the three lines a,b,and c.showed that the value of alleles(Na),the number of effective alleles(Ne)and heterozygosity(H_O)is generally higher than that of other strains.2.Genetic structure of walnut and J.sigillata resources:The results of STRUCTURE analysis showed that walnut and J.sigillata germplasm resources were optimally divided into3 groups,and 171 walnuts and J.sigillata are divided into two subgroups with K=2.The results indicate that there is only a sparse gene exchange or gradual phenomenon between walnut and J.sigillata resources,but there is no obvious population genetic structure within the walnut and J.sigillata resources.Principal component analysis(PCo A)results also support the above conclusions.3.The genetic relationship of walnut and J.sigillata resources:The NJ and UPGMA trees were used to divide the samples.On the whole,there are differences between these two tree-building methods,but the results show that complex relationship between walnus.As an important economic tree species in China,walnuts and J.sigillata have been disturbed by many people for a long time.As a result,the J.sigillata and walnuts do not have obvious geographical characteristics and population genetic structure.Our research results will provide basic koowledge for improving the level of breeding and protecting germplasm resources. |
