Morphological and genetic characterization of sweetpotato F1 hybrids from sweet potato feathery mottle virus infection-reverting and non-reverting genotypes in Uganda

Abstract

Sweetpotato variably reverts from Sweet potato feathery mottle virus infections. In a particular study, crosses between sweetpotato genotypes with varying reversion potential yielded segregating F1 hybrids for the reversion trait. However, information on morphological and genetic diversity of these hybrids is lacking, yet this is important in breeding for reversion. This formed the focus of this study. Using standardized sweetpotato descriptors, a non-reverting parent (Resisto), reverting parents (New Kawogo, NASPOT 11 and NASPOT 1), hybrids from crosses (New Kawogo x Resisto, NASPOT 11 x Resisto and NASPOT 1 x Resisto), and random cultivars Ejumula and Tanzania were morphologically characterized. Simple sequence repeats (SSRs) were used to genetically characterize parents, hybrids, cultivars Ejumula and Tanzania, and a wild highly virus-susceptible sweetpotato relative Ipomoea setosa. There was significant morphological diversity between hybrids, where analysis grouped the 121 hybrids into six clusters. The first seven principal components contributed to 80.98% of total variation.  Molecular variation was significant within and between parents, hybrids and cultivars Ejumula and Tanzania. Number of alleles for SSRs were 2 to 4, Shannon’s information index was 0.325 to 1.061, diversity index was 0.180 to 0.642 and Nei’s pairwise genetic distance was 0.2 to 0.8 indicating a high diversity between genotypes. Molecular analysis grouped hybrids into four clusters. The first four principal components contributed to 90.16% of total variation. Number of leaf lobes, leaf lobe type, and primers IBS82, IBR12 and IBS166 were important in determining diversity within hybrids and these are recommended for identification of genotypes with reversion potential.