Accumulation of Gliadin and Glutenin Polypeptides during Development of Normal and Sulphur-deficient Wheat Seed: Analysis using Specific Monoclonal Antibodies

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Abstract
A panel of monoclonal antibodies with various specificities for wheat (Triticum aestivum L.) gluten polypeptides has been used to analyse the accumulation of these polypeptides in the endosperm of developing wheat seeds grown under normal and sulphur-deficient conditions. Immunoblots of polypeptides fractionated by SDS-PAGE allowed a qualitative analysis of gliadin and HMW glutenin accumulation for high- and low-sulphur seeds 8 d to 30 d after anthesis (d.a.a.). In addition, quantitative analysis of the deposition of various gluten polypeptides was performed, with a solid-phase radioimmunoassay on extracts of seeds harvested 4–36 d.a.a. The initial accumulation of HMW glutenin subunits was detectable at an earlier stage of development than that of gliadins for both normal and sulphur-deficient seeds. The initiation of detectable gliadin accumulation was asynchronous with an order of alpha-gliadins, beta-, gamma- and some omega-gliadins and finally the remaining omega-gliadins. In sulphur deficiency, all gliadins reached a constant proportion of the dry weight of the endosperm earlier than in normal wheat, while a more marked increase in the proportion of HMW glutenin occurred late in grain development. The protein blot studies also identified a putative omega-gliadin polypeptide which was detectable late in seed development and only in sulphur-deficient seeds.