Combining ability and heritability analysis of sweetpotato weevil resistance, root yield, and dry matter content in sweetpotato

Abstract

Efficient breeding and selection of superior genotypes requires a comprehensive understanding of the genetics of traits. This study was aimed at establishing the general combining ability (GCA), specific combining ability (SCA), and heritability of sweetpotato weevil (Cylas spp.) resistance, storage root yield, and dry matter content in a sweetpotato multi-parental breeding population. A population of 1,896 F1 clones obtained from an 8 × 8 North Carolina II design cross was evaluated with its parents in the field at two sweetpotato weevil hotspots in Uganda, using an augmented row-column design. Clone roots were further evaluated in three rounds of a no-choice feeding laboratory bioassay. Significant GCA effects for parents and SCA effects for families were observed for most traits and all variance components were highly significant (p ≤ 0.001). Narrow-sense heritability estimates for weevil severity, storage root yield, and dry matter content were 0.35, 0.36, and 0.45, respectively. Parental genotypes with superior GCA for weevil resistance included “Mugande,” NASPOT 5, “Dimbuka-bukulula,” and “Wagabolige.” On the other hand, families that displayed the highest levels of resistance to weevils included “Wagabolige” × NASPOT 10 O, NASPOT 5 × “Dimbuka-bukulula,” “Mugande” × “Dimbuka-bukulula,” and NASPOT 11 × NASPOT 7. The moderate levels of narrow-sense heritability observed for the traits, coupled with the significant GCA and SCA effects, suggest that there is potential for their improvement through conventional breeding via hybridization and progeny selection and advancement. Although selection for weevil resistance may, to some extent, be challenging for breeders, efforts could be boosted through applying genomics-assisted breeding. Superior parents and families identified through this study could be deployed in further research involving the genetic improvement of these traits.

Breeding for Resistance to the African Sweetpotato Weevils, Cylas puncticollis and Cylas brunneus in Uganda: A Review of the Current Progress

“…Another study revealed similar results (with H 2 =0.49%) and further showed that additive effects contributed the most to SPW resistance and HCA concentration [51]. More recently, a narrow sense heritability (h 2 =0.30) was reported for SPW resistance based on a relatively high population [52]. We hope that the adoption of modern experimental designs such as the row-column designs, which use more replications for field phenotyping, will enable estimation of higher heritability values for SPW resistance for future genomic analyses.…”

Tailoring IPM plans to fight a cloaked pest: helping smallholder farmers combat the sweetpotato weevil in sub-Saharan Africa

“…In part, host plant resistance for SSA may have been difficult to achieve due to breeding tactics that lacked an appreciation of how best to approach the challenge of sweet potato genetic variation. For sweetpotato, there can be superior parental genotypes identified that favor general combining ability, but there are also specific combining abilities which can be identified when tracking a particular trait (such as SPW resistance) for crop improvement (Mugisa et al 2022). While historical trends have led some to regard SPW resistance as less likely to be achieved in SSA, some recent efforts have shown promise (Kagimbo et al 2020;Joseph et al 2022;Mugisa et al 2022).…”

“…For sweetpotato, there can be superior parental genotypes identified that favor general combining ability, but there are also specific combining abilities which can be identified when tracking a particular trait (such as SPW resistance) for crop improvement (Mugisa et al 2022). While historical trends have led some to regard SPW resistance as less likely to be achieved in SSA, some recent efforts have shown promise (Kagimbo et al 2020;Joseph et al 2022;Mugisa et al 2022). In at least one of these recent SSA efforts (Kagimbo et al 2020), there is indication that the germplasm resistance may be based on a mechanism in common with that found from selection efforts that were successful in the USA.…”

Feeding Behavior of Sweet Potato Weevil, Cylas formicarius (Fabricius) (Coleoptera: Brentidae) on Three Sweet Potato, Ipomoea batatas L. Cultivars Grown in Tarlac, Philippines

“…Resistant cultivars often possess distinct chemical compositions, including secondary metabolites and defensive compounds, which deter Cylas formicarius. These defensive compounds alter the flavor and nutritional value of sweet potato tubers (Stevenson et al 2009;Mugisa et al 2022). Some cultivars also possess morphological attributes that alter the feeding preference of weevils (Parr et al 2016).…”