In silico simulation of future hybrid performance to evaluate heterotic pool formation in a self-pollinating crop

Wallace A. Cowling,R. Chris Gaynor,John M. Hickey,Owen Powell,Roberto Antolín,Gregor Gorjanc,Stefan M. Edwards

doi:10.1038/s41598-020-61031-0

In silico simulation of future hybrid performance to evaluate heterotic pool formation in a self-pollinating crop

Wallace A. Cowling, R. Chris Gaynor + Show 5 more

Open Access

https://doi.org/10.1038/s41598-020-61031-0

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Abstract

Hybrid vigour has the potential to substantially increase the yield of self-pollinating crops such as wheat and rice, but future hybrid performance may depend on the initial strategy to form heterotic pools. We used in silico stochastic simulation of future hybrid performance in a self-pollinating crop to evaluate three strategies of forming heterotic pools in the founder population. The model included either 500, 2000 or 8000 quantitative trait nucleotides (QTN) across 10 chromosomes that contributed to a quantitative trait with population mean 100 and variance 10. The average degree of dominance at each QTN was either 0.2, 0.4 or 0.8 with variance 0.2. Three strategies for splitting the founder population into two heterotic pools were compared: (i) random split; (ii) split based on genetic distance according to principal component analysis of SNP genotypes; and (iii) optimized split based on F1 hybrid performance in a diallel cross among the founders. Future hybrid performance was stochastically simulated over 30 cycles of reciprocal recurrent selection based on true genetic values for additive and dominance effects. The three strategies of forming heterotic pools produced similar future hybrid performance, and superior future hybrids to a control population selected on inbred line performance when the number of quantitative trait nucleotides was ≥2000 and/or the average degree of dominance was ≥0.4.

Highlights

Hybrid vigour has the potential to substantially increase the yield of self-pollinating crops such as wheat and rice, but future hybrid performance may depend on the initial strategy to form heterotic pools
The simulations showed no difference in future hybrid performance over 30 cycles of recurrent selection (RRS)-true genetic value (TGV) for the three strategies of splitting the founder population into heterotic pools (Fig. 1)
The control population, selected for per se performance of inbred lines, produced F1 hybrids equal in average performance to those selected by RRS-TGV when the number of quantitative trait nucleotides (QTN) was less than 2000 and/or the average degree of dominance was less than 0.4 (Fig. 1)

Summary

Introduction

Hybrid vigour has the potential to substantially increase the yield of self-pollinating crops such as wheat and rice, but future hybrid performance may depend on the initial strategy to form heterotic pools. We used in silico stochastic simulation of future hybrid performance in a self-pollinating crop to evaluate three strategies of forming heterotic pools in the founder population. Melchinger[20] argued that mean heterosis and hybrid performance in intergroup crosses would be maximized by increasing the difference in allele frequencies between the two subgroups; and secondly that heterotic patterns may be identified on the basis of hybrid performance in diallel or factorial crosses among members of the population. Another approach is a genome-based strategy to identify heterotic groups based on general combining ability (GCA) among the base population[19]. Melchinger and Gumber[21] proposed a multi-stage procedure for establishing heterotic pools, where groups of individuals are initially separated on genetic similarity followed by production and evaluation of testcrosses

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