Combining ability and heterotic pattern in relation to F1 performance of tropical and temperate-adapted sweet corn lines

Abstract

The aims of this study were: to assess the genetic relationship of supersweet corn populations; and to establish the heterotic pattern of 49 supersweet (sh2) corn inbreds on F2S5 generation based on molecular marker data and specific combining ability.Forty-nine inbreds were evaluated using 20 SSR molecular markers, which were allocated into heterotic groups according to the discriminant principal component analysis. Twelve inbreds were crossed in a complete diallel scheme. The 81 entries (hybrids developed, parental lines and three commercial checks) were evaluated in a triple partial balanced lattice design (9 × 9) during the growing seasons of 2016/2017 and 2017. The general combining ability (GCA) and specific combining ability (SCA) were estimated. The SCA values were used to set the heterotic patterns of the parental lines as well. Commercial yield without husk (CYWH) and ear length (EL) were more informative to set the heterotic groups. Additive and non-additive effects were important on the genetic control of the evaluated traits. However, for five of the six traits, the non-additive/dominance genetic effects showed to be more important in both environments. In fact, the hybrids developed among tropical by temperate germplasm had better performance than those ones developed within the temperate germplasm itself. SSR based-genetic distance demonstrate to be a reliable predictor as significant correlation was obtained between genetic distance with hybrid performance (for length of ears, ear height and CYWH) and SCA for all observed traits. The non-additive genetic effect that predominantly controlled all traits was the feasible explanation for the good prediction.

Genetic Parameters in Mesocotyl Elongation and Principal Components for Corn in High Valleys, Mexico

“…While, at the other extreme, Ref. [50] found that the non-additive effects were higher than the additive ones for grain yield, cob weight, and CL for some genotypes [10].…”

“…To have an idea of the magnitude of the aforementioned research, the diallel designs proposed by Griffing can be used [8], which constitute a useful tool to characterize and estimate the capacity of GCA and SCA of parents and their crosses [9], as well as to define the most adequate method of genetic breeding to predict superior crosses and combine the best traits of the parents [10]. In this regard, various results have confirmed the utility of these designs in corn to estimate GCA and SCA, the GCA/SCA relation and the heterosis of the parents [2] and to classify them into heterotic groups based on the genetic expression of the traits studied [11], such as mesocotyl-coleoptile elongation [12], which carries out an important role in the emergence and development of a normal seedling [13], and the components of grain yield [3], which are crucial in corn yield.…”

Utilizing genomic prediction to boost hybrid performance in a sweet corn breeding program

“…Early evidence suggests that non-additive effects represent an important factor in the model, but these effects can also vary from one trait to another ( Zystro et al., 2021a , b ). For instance, Neto et al. (2022) indicate a significant impact of dominance on the SCA estimates in the performance of an F1 population, with a GCA/SCA ratio smaller than one unit for plant height, ear height, ear length, and kernel row number.…”