Heterosis and gene effects of multiplicative characters: theoretical relationships and experimental results from Vicia faba L.

Abstract

Theoretical results were derived to relate the heterosis and the hybrid factor (ratio of hybrid performance to parental mean) of a complex character (seed yield) with the respective parameters of component subcharacters in a multiplicative model. A multiplication factor, which is a function of differences in the parents for subcharecters, was introduced to arrive at multiplicative relationships between the parameters in the model. Under certain assumptions, gene effects of a complex multiplicative trait can be expressed in terms of gene effects for the subcharacters. Data on seed yield and its components in two crosses between Vicia faba minor and major cultivars were used as a numerical example. Theoretical and experimental results indicate that with large complementary differences for subcharacters in the parents, it is possible to find substantial heterosis in the complex character without significant heterosis in its component traits. However, a review of results from the literature shows that multiplication effects are only of minor importance in most crops. Implications for the use of multiplication effects in the breeding of hybrid, synthetic, and line cultivars are discussed.

Heterosis for biomass yield and related traits in five hybrids of Arabidopsis thaliana L. Heynh

“…The positive MPH for seed yield is attributable to an increased 1000-seed weight (C24 Â Aa-0) or an increased number of seeds per plant (Col-0 Â Wei-0 and Ws-2 Â Col-0). While factors for yield components together with multiplication effects can explain heterosis for seed yield (Schnell and Cockerham, 1992;Melchinger et al, 1994), experimental procedures for measuring yield components are considerably more cumbersome and prone to errors in Arabidopsis than in small grains or maize.…”

Genetic association of yield with its component traits in a recombinant inbred line population of cotton

“…Jobson (1991) proposed a conditional multiple linear regression method based on the normal conditional distribution theory. Several approaches have been proposed for analyzing a complex trait with multiplicative component traits (Sparnaaij & Bos, 1993;Melchinger et al, 1994;Piepho, 1995). Both the complex trait and its component traits could be influenced by several factors such as environment, genotype, and genotype by environment interaction effects.…”

Integrating crop growth models with whole genome prediction through approximate Bayesian computation

“…If the relationship 33 among the underlying component traits is nonlinear, epistatic effects can occur on the 34 phenotypic level of complex traits even if the gene action is purely additive when 35 characterized at the level of the component traits (Holland [33]). This phenomenon was 36 first described for multiplicative relationships among traits by Richey [36] and later 37 quantified by Melchinger et al [37]. CGMs, which explicitly model these nonlinear 38 relationships among traits, have therefore the potential to open up novel avenues 39 towards accounting for epistatic effects in WGP models by explicit incorporation of 40 biological knowledge.…”