Abstract
Hybrid wheat breeding is one of the most promising technologies for further sustainable yield increases. However, the cleistogamous nature of wheat displays a major bottleneck for a successful hybrid breeding program. Thus, an optimized breeding strategy by developing appropriate parental lines with favorable floral trait combinations is the best way to enhance the outcrossing ability. This study, therefore, aimed to dissect the genetic basis of various floral traits using genome-wide association study (GWAS) and to assess the potential of genome-wide prediction (GP) for anther extrusion (AE), visual anther extrusion (VAE), pollen mass (PM), pollen shedding (PSH), pollen viability (PV), anther length (AL), openness of the flower (OPF), duration of floret opening (DFO) and stigma length. To this end, we employed 196 ICARDA spring bread wheat lines evaluated for three years and genotyped with 10,477 polymorphic SNP. In total, 70 significant markers were identified associated to the various assessed traits at FDR ≤ 0.05 contributing a minor to large proportion of the phenotypic variance (8–26.9%), affecting the traits either positively or negatively. GWAS revealed multi-marker-based associations among AE, VAE, PM, OPF and DFO, most likely linked markers, suggesting a potential genomic region controlling the genetic association of these complex traits. Of these markers, Kukri_rep_c103359_233 and wsnp_Ex_rep_c107911_91350930 deserve particular attention. The consistently significant markers with large effect could be useful for marker-assisted selection. Genomic selection revealed medium to high prediction accuracy ranging between 52% and 92% for the assessed traits with the least and maximum value observed for stigma length and visual anther extrusion, respectively. This indicates the feasibility to implement genomic selection to predict the performance of hybrid floral traits with high reliability.
Highlights
Bread wheat (Triticum aestivum L.) is the second most important cereal cultivated crop worldwide with 766 million tons produced in 2019 [1]
We showed that absolute values of phenotypic correlations among the evaluated floral traits ranged between 0.3 and 0.90 (p < 0.001) with the highest correlation recorded between anther extrusion and pollen mass (Table S2) [4]
We evaluated the potential of genomic approaches in identifying genes/QTL that could be effectively used to fine-tune the floral traits and greatly redesigning wheat flower
Summary
Bread wheat (Triticum aestivum L.) is the second most important cereal cultivated crop worldwide with 766 million tons produced in 2019 [1]. It was reported previously that Rht-B1b and Rht-D1b dwarfing alleles lead to low anther extrusion that subsequently affect male floral traits [7,8] Given these facts, breeding hybrids in such manner optimizes the exploitation of heterosis and hybrid performance. In cases where the trait is complex and mainly governed by many loci with small effects, genomic selection or (GS) genome-wide prediction (GP) can be an alternative approach to predict the genomic estimated breeding values (GEBVs) for all the genotypes of breeding population [9] These GEBVs allow breeders to select superior genotypes that would be suitable either as parent or for generation advancement of the breeding program. Our aim was to identify the genetic basis of various male and female hybrid potential traits using 196 diverse wheat genotypes by: (1) performing a genome-wide association study to identify loci associated with hybrid male and female potential traits; (2) evaluating the effect of Rht-B1 and Rht-D1 on the floral traits; and (3) investigating the potential of genome-wide prediction (GP) for the evaluated floral traits
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