| Modern breeding tools for sweetpotato improvement are needed to address impediments to the production of this important crop. This research was conducted to improve our knowledge of the inheritance of sweetpotato storage root yield, dry matter, starch and beta-carotene content, and resistance to sweetpotato weevil (SPW) and sweet potato virus disease (SPVD). The study also sought to identify simple sequence repeat (SSR) markers associated with these traits to enhance future genomic sweetpotato improvement.;We developed a bi-parental mapping population of 287 progeny by crossing the Ugandan landrace, 'New Kawogo' with 'Beauregard', a major US cultivar. A total of 405 SSR markers were screened for polymorphism on the parents and selected progeny of which, 250 markers were polymorphic, and 133 were informative and used for population diversity analysis. The pairwise genetic distances among the progeny and parents ranged from 0.2--0.9, and were grouped in to five main clusters, an indication of moderate diversity in the cross.;A total of 284 progeny and the parents were evaluated for two seasons at three sites in Uganda for storage root yield, dry matter, starch and beta-carotene content and genotyped with the 250 polymorphic SSR markers. Estimates of broad sense heritability for storage root yield, dry matter, starch and beta-carotene content were 0.24, 0.68, 0.70 and 0.90, respectively. Storage root beta-carotene content was negatively correlated with dry matter (r=-0.59, P<0.001) and starch content (r=-0.93, P<0.001). Storage root yield was positively correlated with dry matter (r=0.57, P=0.029) and starch (r=0.41, P=0.008) content. Twelve SSR markers were associated with storage root yield, while four, six and eight SSR markers were associated with dry matter, starch and beta-carotene content, respectively.;Sweetpotato weevil resistance was assessed on the basis of field storage root damage severity and total hydroxycinnamic acid (HCA) ester concentration, which have previously been associated with resistance to SPW feeding and oviposition. A moderate broad sense heritability estimate (H2=0.49) for weevil resistance was observed. Mean genotype SPW severity ranged from 1.0--9.0, with severity across sites and seasons slightly skewed to the left or susceptibility. However, a total of 25 progeny exhibited transgressive segregation for field-based SPW resistance suggesting that breeding for resistance to SPW is a realistic goal.;The total HCA ester concentrations of genotypes were different (P<0.0001), with the distribution of genotype mean HCA concentrations skewed to the left. We observed a weak but significant correlation (r=0.103, P=0.015) between total HCA ester concentration and SPW severity. A total of five and seven SSR markers were significantly associated with storage root SPW severity and total HCA ester concentration, respectively.;Genetic studies showed SPVD resistance to be a heritable trait (H 2=0.51). The overall mean genotype SPVD severity scores across sites and seasons were normally distributed. Two progeny showed transgressive segregation for overall genotype mean SPVD severity. A total of seven SSR markers were associated with SPVD resistance in this population.;This series of studies has examined the nature of inheritance of storage root yield, dry matter, starch and beta-carotene content, and resistance to SPW and SPVD in sweetpotato. SSR markers linked to the inheritance of these key traits will be useful for sweetpotato genomic improvement, and they provide useful information as the sweetpotato research community continues to develop improved genomic tools for sweetpotato improvement. |
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