Protein polymer build-up during wheat grain development: influences of temperature and nitrogen timing

The amount and size distribution of polymeric protein, environmentally influenced by temperature and nitrogen timing, is an important factor determining gluten strength in wheat. Differences in mature wheat might be explained by alterations in accumulation and build-up of proteins in the developing wheat grain. One cultivar was grown to maturity in a greenhouse using two temperatures and four nitrogen regimes. Plants were harvested during grain development and protein compositions were determined. Proteins were accumulated and built up similarly independent of temperature and nitrogen regime. Temperature influenced the protein concentration significantly, for all protein types throughout the grain development period and at maturity. The time for increase in amount of polymeric proteins differed with temperature if time was measured as days after anthesis, but not if time was measured as degree-days. Different temperature regimes did not generally result in changes in amount and size distribution of polymeric protein. The combination of lower temperature, different nitrogen regimes and one of the cultivations led to changes in the amount and size distribution of polymeric protein in mature grains. These differences were due to a change in amount of SDS-extractable polymeric and large monomeric proteins during grain development, indicating influences on disulphide bond formation. (C) 2004 Society of Chemical Industry.