The Influence of Recovery Treatment on the Effects of a Brief Heat Shock on Wheat. II. Fractional Protein Accumulation During Grain Growth

Abstract

In this study, we have sought to identify the nature of the response to both moderately high (25-32�C) and very high (>32�C) temperatures by examining their interactive effects on the accumulation of functionally important proteins during grain-filling. In particular, we wished to determine if the deleterious effects of very high temperature could be alleviated by subsequently cool conditions. To this end, wheat cv. Oxley was exposed to either 21/16 or 40/16�C (day/night) from 15 to 19 days after anthesis and subsequently grown under one of three temperature regimes until maturity: 21/16 (control), 27/22 or 30/25�C. Grain samples were taken throughout grain growth and analysed for protein content and composition. Wheat proteins were separated and quantified as albumin,globulin, monomer, SDS-soluble polymer and SDS-insoluble polymer using size-exclusion high-performance liquid chromatography. The various protein fractions responded differentially and usually additively to moderately high and very high temperatures during grain-filling. Cool post-shock conditions did not alleviate the effects of very high temperature on grain protein composition. Heat treatments reduced polymer:monomer ratio because the accumulation of monomer was reduced less than that of polymer.