Correlation analysis between heterosis and genetic distance evaluated by 15K SNP array in hybrid wheat

Hybrid breeding is a promising technology for improving wheat yield potential and stability, especially in marginal environments. However, creating hybrids with strong heterosis is challenging. This study screened T307 restorer lines and seven thermo-photosensitive genic male sterile (TPGMS) lines genotyped by a 15K SNP array. Subsequently, based on the genetic distances (GDs) among parental lines, two male sterile lines and 16 restorer lines representing close, middle, and distant genetic distances relative to each sterile line were selected for production of 18 hybrids. The hybrids were subjected to a two-year field trial for assessment of 27 agronomic and end-use quality characteristics. We found that the GDs among the selected 2 sterile lines and 16 restorer lines ranged from 0.04 to 0.66, with an average of 0.47. The 18 parental lines are divided into five groups based on the phylogenetic tree. The relationship between GDs and the mid-parent heterosis showed a weak negative correlation for a majority of characteristics. Likewise, for the grain yield per plant, non-significant negative correlations were observed between GDs and the mid-parent heterosis (MPH), better parent heterosis (BPH), and commercial check heterosis (CCH). However, hybrid S003*R080 with the genetic distance of 0.36 and hybrid S005×R084 with the genetic distance of 0.44, demonstrated superior performance across all tested attributes. This study suggests that SNP marker based genetic distance is a poor predictor of heterosis and high heterosis can be obtained in hybrids of moderately distant parental lines.