Analyses of the Genetic Diversity in Cassava Germplasm by Using SRAP Markers

An analyses of the genetic diversity in 80 cassava accessions,among which 76 were introduced from South America,Thailand and African,and 4 varieties belong to South China series,by using 31 pairs of SRAP markers.207 loci were obtained totally,and 201 were polymorphic loci,the average polymorphism level was 97.1%,3 to 11 alleles were detected by each pair of primer,with an average of 6.7,the fragment size of PCR products ranging from 250bp to 1750bp.According to the genetic similarity coefficient among different strains and the UPGMA method,with the similarity coefficient criteria of 0.635 these 80 accessions were clustered into 4 groups,which consist of 38,6,33 and 3 strains respectively.The value of some parameters are as following: the population heretozygosity(Ht) was 0.3201,the genetic diversity index was 0.4766,the mean value of the population genetic diversity was 0.2762,the coefficient of genetic differentiation was 0.2181 and the coefficient of gene flow was 1.7921.These results indicated that the introduction of foreign resources enriched cassava germplasm bank in China,and expanded our country's cassava breeding basis.