Genetic Diversity Among Air Yam (Dioscorea bulbifera L.) Local Varieties in Brazil Based on SSR Markers

Dioscorea is the largest genus of the Dioscoreaceae family and has a wide variety of species of economic interest, for their edible and medicinal properties, including air yam, D. bulbifera L. This study aimed to characterize, using microsatellite markers, the genetic diversity of 42 local varieties, originating from several municipalities in Brazil, but mainly the States of São Paulo (SP) and Minas Gerais (MG). We developed an enriched genomic library for D. bulbifera, since there were no specific primers for this species. This genomic library resulted in seven primers, six of them polymorphic. Data was analyzed as binary data due to the polyploidy of this species. A total of 26 alleles (bands) were found, with an average of 3.7 alleles per locus. The Shannon Index ranged between 0.18 and 0.51 among the seven loci, the discrimination power (D) ranged between 0.85 and 0.96, and the expected heterozygosity from 0.08 to 0.35. Both principal coordinate and cluster analyses, using the Jaccard index, indicated no clear separation among the accessions according to their origin. However, the 13 accessions from Conceição dos Ouros (MG) were clustered to the left side of principal coordinate 1 axis, and were also clustered into one sub-group in the cluster analysis. On the other hand, the 25 accessions from eight municipalities of São Paulo were scattered into several sub-groups in both analyses. Therefore, this study showed a slight spatial structure among the accessions and a considerable level of genetic diversity in D. bulbifera maintained by traditional farmers in Brazil.