Comparison of sudden heat stress with gradual exposure to high temperature during grain filling in two wheat varieties differing in heat tolerance. II. Fractional protein accumulation

Abstract

Two varieties of wheat differing in heat tolerance (cvv. Egret and Oxley, tolerant and sensitive, respectively) were exposed to either a sudden or gradual (6°C h -1 ) increase from 20 to 40°C to determine if the rate of temperature increase used in controlled-environment studies (1) alters the accumulation of functionally important proteins during grain-filling, and (2) affects the ability to discriminate between heat tolerant and sensitive varieties of wheat. After heat treatment, 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 rate of temperature increase exerted a significant influence on the accumulation of total wheat protein and its fractions, and protein fractions differed in their responses to the suddenness of heat stress. The acclimation to heat stress afforded by a gradual increase to high temperature can mitigate the effects of heat stress on fractional protein accumulation, and consequently grain protein composition at maturity. Furthermore, the ability of wheat to acclimate to high temperature varies between genotypes, and this needs to be taken into account when selecting for heat tolerance. * Part I, Aust. J. Plant Physiol., 1995, 22, 935-944. * Abbreviations used: SE-HPLC (size-exclusion high performance liquid chromatography); SDS (sodium dodecyl sulfhate); DAA (days after anthesis).

Remobilization of Nitrogen and Carbohydrate from Stems of Bread Wheat in Response to Heat Stress during Grain Filling

“…The gradual increase and then decrease in the temperature of the phytotrons mimics the actual situation encountered by heat‐stressed plants under natural conditions. This has been proved more efficient than the sudden increase in studying the effect of heat stress on wheat (Stone and Nicolas 1998) and led to clear variations among genotypes. Relative humidity was always in the range of 30–60 % during the period of the heat‐stress treatment although it was not controlled.…”

Heat Stress in Wheat during Reproductive and Grain-Filling Phases

“…Whilst grain protein content increases under heat stress, the functionality of protein significantly decreases (Corbellini et al, 1997), affecting end-use quality. Total grain protein content of the crop decreases under heat stress because heat stress decreases grain yield (Stone and Nicolas, 1998;Castro et al, 2007). Heat stress also decreases the duration, but not rate, of protein deposition in the grain (Castro et al, 2007).…”

“…Heat stress during grain-filling phase affects the grain protein contents (Wardlaw et al, 2002;Gooding et al, 2003) through reductions in starch deposition, which influences protein concentration by allowing more nitrogen per unit of starch (Stone and Nicolas, 1998). Although the daily flow of carbon and nitrogen into grain increases with increasing temperature, carbon flow decreases per degree-day (Wardlaw et al, 1980;Daniel and Triboi, 2000).…”

Genotypic and temperature effects on wheat grain yield and quality in a hot irrigated environment

“…High temperatures during grain filling have been reported to significantly increase grain protein content but, in contrast, decrease protein functionality (Corbellini et al. 1997, Stone and Nicolas 1998). High temperature affects the gliadin to glutenin ratio, the degree of complex protein aggregates formation and the amount of heat shock proteins produced (Blumenthal et al.…”