Gluten subfractions of wheat storage proteins are affected by high night temperature during grain formation

Gluten (gliadin + glutenin) protein in wheat flour is affected by high temperature (day and/or night) resulting in undesirable consequences on dough quality. A study was conducted with early and late-maturing wheat genotypes, to assess the spatial (superior- central and inferior- apical and basal spikelets) variation in the composition of gluten subfractions in the developing ear under high night temperature (HNT). We hypothesised that protein content in the superior and inferior grains may show a differential quantitative and qualitative response to HNT. HNT resulted in a significant increase in protein content which exhibited a strong (r = -0.44*) negative correlation with sedimentation volume (SV) that determines baking quality. The late-maturity genotypes were more responsive to HNT with changes in & omega;-5 and & gamma; gliadin subfractions of both superior and inferior spikelets, though a consistent trend was not established. The proportion of high molecular weight (HMW) glutenins increased, whereas low molecular weight (LMW) glutenins reduced in most of the genotypes under HNT. Both HMW and LMW glutenins revealed significant positive (r = 0.43* and r = 0.81***, respectively) correlation with SV. The expression analysis of genes for gluten subfractions showed a significant decrease in transcript abundance of & alpha;, & omega;-5, & gamma;, HMW, and LMW fractions under HNT.