Genomic Selection for Increased Water-Soluble Carbohydrate Concentration in Wheat

Water-soluble carbohydrates (WSC) accumulate in wheat when assimilate supply is greater than assimilate demand from sinks. This characteristic has been identified as a potentially useful drought avoidance trait, as plants that accumulate carbohydrate reserves can remobilise that assimilate to contribute to grain filling under unfavourable growing conditions such as terminal drought. Investigation of the genetic control of WSC concentration is needed to determine the potential for genetic improvement of this trait.

Experiments clearly group into well-watered and water deficit environment clusters in this study, showing complex genotype ×environment interactions. Within these clusters, genetic correlations between experiments were high. Line mean heritability for each cluster ranged from H² = 0.43 to 0.79 across experiments. There was no correlation between grain yield and WSC, although significant correlations were observed in both well-watered and water deficit experiment clusters for reduced tillering, fewer grains per m² and greater grain weight.

Genomic estimated breeding values (GEBVs) from the whole-genome marker profiles for both the well-watered and water deficit environment clusters of experiments were predicted separately from the models used. The GEBVs for each of these target populations of environments showed 65-70% relative accuracy compared to phenotypic predictions. This translates to an approximately 30-40% greater genetic gain for genomic selection per unit time when the duration of the breeding cycle is reduced by half at the same time. Genomic selection shows promise in improvement of this complex trait and may be more effective than phenotypic selection or marker assisted selection.