Polymerization of Glutenin during Grain Development and Quality Expression in Winter Wheat in Response to Irrigation Levels

Abstract

ABSTRACTChanges in the content and size distribution of glutenin were monitored using size‐exclusion‐high performance liquid chromatography (SE‐HPLC) during grain filling under field conditions in two seasons. Effects of irrigation levels on the constituent polypeptides (high molecular weight and low molecular weight glutenin unit), polymerization index (the percentage of sodium dodecyl sulfate [SDS]‐insoluble glutenins in total glutenins) of glutenin, glutenin macropolymer (GMP) particle size, dough mixing properties, and baking quality were examined. Drought or excess watering led to a reduced polymerization index at maturity resulting from modification of grain desiccation and accumulation of SDS‐insoluble glutenin. Glutenin particle size at maturity decreased under drought or excess watering and was associated with reduced ratio of a high molecular weight glutenin subunit to a low molecular weight glutenin subunit (HMW‐GS:LMW‐GS). The polymerization index of glutenin and GMP particle size were significantly positively correlated to dough stability times and loaf volume whereas no significant correlation existed among flour protein content, wet gluten content, dough stability times, and loaf volume. Therefore, dough mixing properties and baking quality were affected by irrigation levels mainly through changing the polymerization index of glutenin and GMP particle size in flour.