Effects of environmental temperature during maturation on protein characteristics in spring wheat (Triticum aestivum cv. Haruyokoi)

Wheat (Triticum aestivum cv. Haruyokoi) gluten proteins are important contributors to wheat flour quality. Numerous studies have examined the effects of heat stress on gluten proteins. We clarified the relationship between growth temperature and the characteristics of storage proteins in spring wheat grown under mild conditions (<30 C). As the growth temperature increased, crude protein content also increased and the activity of protein disulfide isomerase (PDI), which is involved in the folding and transport of gluten proteins, decreased. The growth temperature also affected the amount of aggregated storage proteins, with an increase in sodium dodecyl sulfate (SDS)-insoluble proteins observed under high-temperature conditions. From these results, it was inferred that high growth temperatures caused an environment where nonspecific aggregation is likely to occur. The accumulation of specific proteins was also affected. The high-molecular-weight glutenin subunit (HMW-GS) Dx5 encoded by Glu-D1d allele, which has a marked impact on the viscoelastic properties of dough characteristics, showed high accumulation under high growth temperatures. These effects of growth temperature on storage proteins appear to affect the formation of glutenin macropolymer, which in turn affects the physical properties of the dough. As global warming continues, this study could provide helpful information for long-term predictions of wheat quality.