ARS | Publication request: Effect of high temperature on cell structure and gluten protein accumulation in the endosperm of the developing wheat (Triticum aestivum L.) grain

Submitted to: International Gluten Workshop
Publication Type: Abstract Only
Publication Acceptance Date: July 1, 2009
Publication Date: September 1, 2010
Citation: Hurkman Ii, W.J., Tanaka, C.K., Wood, D.F., Vensel, W.H., Altenbach, S.B., Dupont, F.M. 2010. Effect of high temperature on cell structure and gluten protein accumulation in the endosperm of the developing wheat (Triticum aestivum L.) grain. International Gluten Workshop. p. 50.

Technical Abstract: High temperature during grain fill is one of the more significant environmental factors that alters wheat yield and flour quality. To identify endosperm responses to high temperature, cell structure and gluten protein composition were investigated in developing wheat (Triticum aestivum L. cv. Butte 86) grain using microscopy and proteomic approaches. Grain was produced under a moderate (24/17°C, day/night) or high temperature regimen (37/28°C, day/night) imposed from anthesis to maturity. The 37/28°C regimen decreased the duration of grain fill from 42 to 21 dpa and substantially reduced fresh weight and protein amount per grain. Under the 37/28°C regimen, the A-type starch granules increased in number and decreased in size and the B-type granules decreased in both number and size. In addition, A-type starch granules in mature grain exhibited pitting that might be due to enhanced action of starch degradative enzymes. Protein accumulation was similar under both temperature regimens. Protein bodies that arose early in development coalesced during mid to late development to form a continuous protein matrix that surrounded the starch granules. However, the proportion of protein matrix in endosperm cells increased in mature grain produced under the 37/28oC regimen. A fraction enriched in gliadins and glutenins was isolated from endosperm collected at selected time points during grain fill under the 24/17°C and 37/28°C regimens and proteins were separated by 2-DE and quantified. Individual gluten proteins were identified with a high level of confidence by MS/MS using three proteases, two search engines, and an improved database. Hierarchical cluster analysis of protein profiles revealed that the sequential timing of peak accumulation of individual gliadins and glutenin subunits was similar for both temperature regimens. The 37/28oC regimen resulted in small quantitative differences in a number of gluten proteins in the developing and mature grain. The changes in starch granule number, size and structure, and shifts in gluten protein levels and relative composition reveal that many gene products in the endosperm are affected by high temperature. Although reproducible, the changes are small, making it difficult to clearly identify genetic targets for protecting quality from the effects of high temperature during grain fill.