Characterization of Tanzanian elite sweet potato genotypes for sweet potato virus disease (SPVD) resistance and high dry matter content using simple sequence repeat (SSR) markers

Abstract

A total of 57 sweet potato genotypes with high dry matter content and resistant to sweet potato virus disease (SPVD) were characterized using four simple sequence repeat (SSR) markers. The germplasm included 20 genotypes identified as having high dry matter content and 25 accessions tolerant to SPVD in a study conducted in Tanzania in 2008. The total number of alleles within the 57 genotypes across 4 loci was 395, with an average of 4 alleles per locus. The unweighted pair group method with arithmetic mean (UPGMA) and analysis of molecular variance (AMOVA) using generated SSR data, grouped the 57 genotypes into two major clusters, with mean pair-wise genetic distance of 0.55. No specific grouping was observed in relation to SPVD resistance, dry matter content and geographic location. The four microsatellites markers distinguished the 57 Tanzanian sweet potato genotypes into two major clusters. The relatively high level of genetic diversity indicates broad genetic base for sweet potato breeding in Tanzania. The results obtained demonstrate the efficiency of SSR marker technique for the assessment of genetic relationships and distinguishing between Tanzanian sweet potato genotypes. The findings of this of this study, provide valuable information to breeders to facilitate cost effective germplasm conservation and development of improved sweet potato varieties resistant to SPVD and containing high dry matter.

Key words: Simple sequence repeat (SSR), Ipomoea batatas, cluster analysis, genetic diversity.