In this study, we have sought to identify the nature of the response to both moderately high (25-32ºC) and very high (>32ºC) 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 40/16ºC (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 30/25ºC. 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.

Full text doi:10.1071/PP9960605

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