Genetic diversity and population structure of sweet cassava using simple sequence repeat (SSR) molecular markers

Abstract

The objective of this study was to evaluate the population structure and genetic diversity among 66 sweet cassava (Manihot esculenta Crantz) traditional accessions collected in Maringa, Parana, Brazil, using microsatellite molecular markers. Population structure was analyzed by means of genetic distances and probabilistic models; allelic frequencies were used in order to assess the genetic diversity indexes (Ht , Ho, PIC, % polymorphism and number of alleles) for each locus studied. All evaluated loci were polymorphic and the average was highly heterozygote. The number of alleles per locus was low, suggesting that restrict genetic base is a consequence of accession exchange and a reduced number of ancestors in the population. The polymorphic information content (PIC) values showed considerable genetic diversity with a mean value of 0.5076 and peak of 0.5707 for locus GA140. The microsatellites markers revealed a wide genetic variability among the traditional accessions evaluated. Moreover, the sweet cassava populations were separated in two groups using two analytical methods (probabilistic and genetic distances). The most divergent accessions were BGM 17, BGM 20, BGM 51 and BGM 95. On the other hand, the most similar accessions were BGM 25, BGM 33, BGM 37, BGM 59 and BGM 214. Hybrid combinations formed by the most divergent combinations, especially between BGM 51 × BGM 296, BGM 95 × BGM 222 and BGM 20 × BGM 12, are the most promising ones for future sweet cassava breeding programs