Impact On Genetic Diversity Of Cassava Accessions Collected In China And Molecular Tagging Of Dry Matter (DW) By SSR Markers

Cassava is the most important energy produced root tuber crop in the tropic. Food energy supplied by cassava is rank 4th after rice, maize and sugarcane. There are 600 million people survive feed cassava in the world. Higher 30 to 40 percent of dry matter in cassava fresh root tube contains rich starch could be important resource of starch industry And there are rich protein, vitamin C, carotenes, calcium, and potassium in the cassava leaves useful for feed purpose. All these utilizations request cassava varieties with different elite genes for special aims.The heterozygous character of cassava genome is available to choose better clones but it diffuse the hybrid breeding. Because heterozygy make severe separation of F1 population and it's not easy to foresee selected genetic advantage. However, developing genotype selection pathways by explore germplasm structure to enhance genetic potential for multiple demand to cassava will be focus for research.In the studies, almost all cassava primary accessions collected in China have been screened by SSR markers in whole genomic level for the purpose of eyebird genetic diversity level and discovering genes for special economic use. Meanwhile, QTLs screen of Dry matter (DW) of root tuber have been carried out by combining bulk segregation analysis (BSA) and SSR techniques to search markers with major effective of DW. The results shown as followings:The 28 of 40 diversity SSR markers have been inspected through screen to 89 cassava accessions, 88 diversity alleles out of 93 have been shown and the average diversity reached to 94.6%. The number of allele each locus is from 2 to 5, average alleles was 3.1. It indicated that there is better SSR allele diversity in total cassava germplasm population suitable use to evaluate genetic diversity level. Four genetic parameters, Ht, Hs, Dst and Gst (=Dst/Ht), have been calculated usedGensury software. It is shown that the gene diversity in the total accessions (H) is moderate (0.5399), and the average gene diversity within populations is smaller (0.4406), gene draft frequent was 0.0994 and index of gene differentiation reach to 0.1784. Cassava is a kind of cross pollinated crop and regenerated based on somatic clones, so there is some kind of...