Unravelling the genetic diversity of water yam (Dioscorea alata L.) accessions from Tanzania using simple sequence repeat (SSR) markers

Abstract

Water yam (Dioscorea alata L.) is among the most cultivated species used as a source of food and income for small-scale farmers in Tanzania. However, little is documented about Dioscorea species available in Tanzania, including their genetic diversity. This study used ten polymorphic microsatellite markers to determine the genetic diversity and relationship of 63 D. alata accessions from six major producing regions. Results revealed a polymorphic information content (PIC) of 0.63, while the number of alleles per locus ranged from 4 to 12 with a mean of 7.60. The expected heterozygosity ranged from 0.20to 0.76, with a mean of 0.53, which suggests moderate genetic diversity of D. alata accessions. Kagera region had the highest mean number of (1.5) private alleles. Analysis of molecular variance revealed that 54% of the variation was attributed to within individual, 39% was attributed to among individual while among population contributed 7% of the total variation. The highest Nei’s genetic distance (0.43) was for accessions sampled from Kilimanjaro and Mtwara regions. Principal coordinate analysis and cluster analysis using Unweighted Paired Group Method using Arithmetic (UPGMA) grouped D. alata accessions into two major clusters regardless of geographical origin and local names. The Bayesian structure analysis confirmed the two clusters obtained in UPGMA and revealed an admixture of D. alata accessions in all six regions suggesting farmers’ extensive exchange of planting materials. These results are helpful in the selection of D. alata accessions for breeding programs in Tanzania.

Genetic diversity of yam (Dioscorea sp.) through morphological and molecular markers

“…The number of alleles (Na) and the effective number of alleles (Ne) observed in this study may suggest high genetic diversity among the genotypes evaluated. The larger the number of effective alleles in a population, the greater its diversity (Massawe and Temu 2023). Values of Na of 1.9 and of Ne of 1.77 were obtained in a study on the species D. The expected heterozygosity also reveals the high genetic diversity among the genotypes evaluated.…”

“…High polymorphism (83.62%) was also observed in studies on Dioscorea spp. (Castañeda-Cardona et al 2020) in assessment of the genetic diversity of 21 local strains of yam from China using ISSR primers (93.5%) (Wu et al 2014), and 92% of the loci were polymorphic in a study of the genetic diversity of D. alata L. using SSR primers (Massawe and Temu 2023).…”