Heat stress and genotype affect the glutenin particles of the glutenin macropolymer-gel fraction

Genetic and environmental factors that affect the formation of glutenin macropolymer (GMP) particles were investigated by growing Lance 5+10, Lance 2+12, Warigal 5+10 and Warigal 2+12 lines under widely differing temperature regimes in greenhouse conditions. The GMP characteristics and mixing properties of flour extracted from mature wheat kernels were systematically studied. The amount of GMP is more sensitive to growing conditions than protein quantity. With the exception of severe heat stress conditions, 5+10 varieties produce larger glutenin particles than 2+12 varieties. The HMW/LMW ratio of GMP is lowered by heat stress, but glutenin particles become larger. In heat stress effects on dough mixing properties, glutenin particle size is more relevant than GMP quantity for dough development time; and GMP quantity is more relevant for band-width at peak resistance. A hyperaggregation model is used to explain how heat stress controls glutenin particle formation.