Genetic investigation of contributions of embryo and endosperm genes to malt Kolbach index, alpha-amylase activity and wort nitrogen content in barley

A genetic model is proposed for the analysis of embryo and endosperm effects as well as GE interaction effects. An investigation of three malting quality traits in grains of seven parents and their F(2)s was undertaken in a half-diallel cross of barley (Hordeum distichum L.) over 2 years. The results indicated that the malt Kolbach index (KI), alpha-amylase activity (alpha AA) and wort soluble nitrogen (Wort-N) are controlled by both embryo genetic effects and endosperm genetic effects. Variance of the endosperm additive effects was obviously larger than that of the embryo additive effects. In the contribution of the embryo genetic effects to variation in malt alpha AA and Wort-N, the dominance effects were considerably larger than the additive effects. The endosperm dominance effects constituted a major part of the total genetic effect on the KI. Significant endosperm GE interactions were also detected in the malt traits concerned. Endosperm general heritability (h(e)(2)) tended to be larger than interaction heritability (h(oE)(2) or h(eE)(2)) for all the traits. Endosperm heterosis was observed to be significantly positive for alpha AA but negative for Wort-N in the F-2 seed generation. Prediction of main gene effects for seven parents showed that 'Ganmu 2' and 'Supi1' were suitable parental varieties for malt alpha AA and Wort-N improvement. Our genetic model for malting quality traits and its application in breeding are discussed.