Construction And Evaluation Of Core Collection In Cynodon Rich

Cynodon,also called Bermudagrass,is one of the three world-famous warm-season turfgrasses,it is also a high quality pasture.Bermudagrass distributes wildly and has a large genetic diversity.There is abundant native bermudagrass germplasm in China.In this study,the method of construcing Cynodon core collection was first studied,then the core collection was constructed based on phenotypic?SSR and SCoT data of 607 native bermudagrass germplasm keeped in the Tropical Crops Genetic Resources Institute,Chinese Academy of Tropical Agricultural Sciences.Expect this study can lay the foundation for further research in Cynodon.The main results were as follows:(1)The method of construcingCynodon core collection was selected based on phenotypic and molecular data.The selected contents contained 3 sampling methods,7 total sampling proportions,3 sampling proportions within group,6 hierarchical cluster methods suited to phenotypic and molecular data respectively,3 genetic distances suited to phenotypic data and 4 genetic distances suited to molecular data.The results were as follows,we chose stepwise cluster preferred sampling as the sampling method,20%was chosed as the total sampling proportion,square root proportion was chosed as the sampling proportion within group.Several hierarchical cluster methods had no significant difference in phenotypic data analysis,we chose UPGMA.The hierarchical cluster method suited to molecular data was Ward's method.Different genetic distances had no significant difference to either phenotypic or molecular data in the process of constructing a core collection.We chose Mahalanobis distance for genotypic data and Nei and Li distance for molecular data.(2)The first core collection(PCore)was constructed by methods mentioned above based on phenotypic data in Cynodon.PCore contained 108 Cynodon germplasms.Using mean difference percentage,variance difference percentage,coincidence rate of range and changeable rate of coefficient of variation 4 parameters to evaluate PCore.Then evaluate PCore through principle component analysis and phenotypic correlations.The results showed that PCore could successfully remain the genetic diversity,genetic structre and phenotypic correlations in phenotype.(3)The second core collection(SSRCore)was constructed based on SSR molecular data in Cynodon.SSRCore contained 110 Cynodon germp las ms.Calculate average observed number of alles,average effective number of alleles,average Nei's gene diversity,average Shannon-Weaver information index,the percentage of polymorphic loci of SSRCore.And evaluate SSRCore through remaining ratios at these 5 parameters.After that,compare SSRCore and initial collection by principal component analysis based on SSR molecular data.The results showed that SSRCore could remain the genetic diversity and genetic structer in SSR molecular marker information well.(4)The third core collection(SCoTCore)was constructed based on SCoT molecular data in Cynodon.The evaluation method of SCoTCore was the same as SSRCore.The results showed that SCoTCore could remain the genetic diversity and genetic structure in SCoTmolecular marker information well.(5)The fourth core collection(PMCore)was constructed based on phenotypic,SSR and SCoT synthetical data in Cynodon.Evaluate PMCore in both phenotypic and molecular two sides.Finally the results showed that PMCore could remain the genetic diversity and genetic structure in both phenotype and molecular marker information well.(6)Compare PCore,SSRCore,SCoTCore and PMCore in phenotypic and molecular two sides mutually.In terms of preservation genetic diversity in molecular marker information,4 core collections all behaved well,SSRCore and SCoTCore exceeded PCore and PMCore slightly;In terms of preservation genetic diversity in phenotype character,PCore and PMCore exceeded SSRCore and SCoTCore largely.In general,PCore and PMCore exceeded SSRCore and SCoTCore,PCore and PMCore could remain the genetic diversity in both phenotype and molecular marker information well.But PCore and PMCore were high similar in both phenotype and molecular information two sides,so it was hard to decide which one was better.In consider that PMCore was constructed based on phenotypic and molecular integrated data,so we finally chose PMCore as the best core collection of Cynodon.