Heterosis for the root distribution trait in common bean

Abstract

Heterosis has been one of the most studied phenomena since genetic studies were conceived. Knowledge of this phenomenon for the root distribution trait in beans (Phaseolus vulgaris L.) can favour the development of genotypes that are more tolerant to abiotic stresses. This study aimed to verify the occurrence of heterosis for the root distribution trait in hybrid F1 populations of common bean derived from crosses within and between gene groups. Thirty-six populations (six parents and 30 hybrids) were evaluated under field conditions in the agricultural years 2016/17 and 2017/18. The root distribution was assessed with the adapted Bohm method. The genotypes responded similarly to environmental changes (absence of an interaction). However, the root distribution differed significantly between the agricultural years. Comparisons between the mean of hybrids from crosses within each gene pool and the mean of parents did not reveal heterosis. The comparisons between gene groups showed significant differences only between BRS Embaixador x IPR Uirapuru, CBS 14 x IPR Uirapuru, and BAF 53 x IPR Uirapuru and the mean of parents. The absence of heterosis in the root trait can be explained by the degree of kinship between the gene groups, as well as some epistatic interactions.

Research Article Genetic structure of root distribution in genotype crosses of Mesoamerican common bean

“…In common bean, based on the complete diallel cross design, comparisons between the means of the parents and those of the segregating generations supported the assumption of predominant additive inheritance of the trait root distribution (de Melo et al, 2016(de Melo et al, , 2018. In addition, it has been found that heterosis is not fundamental for root distribution, even when plants of different gene groups of common bean are crossed; the authors suggested that possible epistatic effects influence this trait (Grigolo et al, 2021). Likewise, a study on the inheritance of common bean root distribution reported significant additive x additive epistatic effects, with consequent implications for plant selection (Araújo et al, 2005).…”

Implications of additive x additive epistasis for common bean breeding

“…In this research, due to the insu cient amount of seeds, the F 1 populations were not planted either. However, this progeny had been evaluated for the same traits in the eld in the previous two years (Cerutti et al 2020;Grigolo et al 2021). In those experiments, 30 different F 1 hybrid combinations as well as the F 2 progenies and parents had been evaluated.…”

“…In general, the progress of breeding programs in selecting progenies with a satisfactory root development has been slow, since other, shoot-related traits are prioritized (Tracy et al 2020). For common bean, the presence of transgressive segregants has been reported as an exception rather than the rule (Toaldo et al 2013;de Melo et al 2016;Grigolo et al 2021). Of the few progenies detected, a signi cant portion was found to have an inferior performance to the parents (Cerutti et al 2020;Grigolo et al 2021).…”

“…For common bean, the presence of transgressive segregants has been reported as an exception rather than the rule (Toaldo et al 2013;de Melo et al 2016;Grigolo et al 2021). Of the few progenies detected, a signi cant portion was found to have an inferior performance to the parents (Cerutti et al 2020;Grigolo et al 2021). A possible explanation for this pattern could be the presence of epistatic components that in uence the trait.…”