Study On Genetic Diversity Of Crataegus Songorica K.Koch. In Xinjiang

Wild hawthorn,is one of the most important germplasm resources of wild fruit forest in Tianshan Mountains,Xinjiang,lots of which were distributed in part of the mountains in Xinjiang,and Crataegus songorica K.Koch.was mainly distributed in Daxigou of Huocheng County.In recent years,genetic diversity of wild hawthorn germplasm resources has been seriously damaged.However,wild hawthorn,the research and application of which is rather backward,especially the genetic diversity was rarely reported.In this study,with 92 C.songorica K.Koch.,the genetic diversity and genetic structure of which was analyzed by SSR,ISSR molecular markers and the observation of 31 phenotypic traits.The aim of this study was to provide theoretical basis and scientific basis for rational conservation,effective utilization,genetic improvement and breeding of C.songorica K.Koch.in Xinjiang.The main results are as follows:?1?The F-value of 31 traits were ranged from 0.266 to 15.128,the mean phenotypic differentiation coefficient was 13.41%,the variation among populations accounted for 13.57%,indicating that within population is the main source.The Shannon-Wiener index and Simpson diversity index of five different populations of C.songorica K.Koch.were 3.342 2 and 0.811 9,respectively.According to principal component analysis,the contribution rate of 11 principal components was 77.331%,and the contribution rate of leaf and fruit were higher.The population of C.songorica K.Koch.were clustered into two categories by system cluster analysis,showing some regional characteristics.?2?A total of 303 loci were detected from five populations by 12 ISSR primers.The PIC and polymorphism rate were 0.95 and 98.35%,Nei?s diversity index,Shannon?s diversity index,the gene diversity within population?H_s?and the total population?H_t?were 0.326 8,0.493 9,0.277 9 and 0.323 5,respectively.The genetic differentiation coefficient(G_st)was 0.140 8,and the gene flow?N_m?was 3.051 1.The cluster analysis showed that the genetic similarity coefficients were between 0.53 and 0.87 among the samples,so the genetic similarity among individuals was higher,and the genetic relationship was closer.?3?A total of 42 pairs of SSR primers with good polymorphism were selected from 221 pairs of SSR primers with different source.Twenty-five pairs were selected from 130 pairs of SSR primers in Rosaceae,and 17 pairs were from 91 pairs of SSR primers which were designed by EST sequences of pear and apple genus.The results showed that SSR primers had some commonality among different genera.?4?A total of 739 loci were detected from five populations by 42 SSR primers,the primer diversity information index and polymorphic rate were 0.91 and 90.60%.Nei?s diversity index,Shannon?s diversity index,the gene diversity within population?H_s?,the total population genetic diversity?H_t?,G_stt and N_m were 0.233 5,0.365 4,0.198 2,0.229 7,0.137 2 and 3.146 4,respectively.The genetic similarity coefficients were between 0.46 and 0.95 among 92 samples,five populations formed two sub-types,which showed obvious regionality,and the different habitats were the main reason for the differences between groups.?5?The genetic diversity of C.songorica was high,and there was a visible genetic differentiation within population,moreover differentiation trends had regional characteristics.Although there are some differences between the two molecular markers,the overall trend is consistent,genetic diversity should not be confined only by geographical or environmental differences,moreover genetic diversity studies at the molecular level should be the mainstay in the study of genetic diversity of germplasm resources in future.