Responses of Glutenin Macropolymer Particle Distribution to Heat Stress in Wheat Grain

Glutenin macropolymer (GMP), a major glutenin fraction, is affected by both genotypic and environmental factors. However, few studies have focused on the effects of heat stress on the characteristics of GMP in wheat ( Triticum aestivum L.) grains. The high‐yielding winter wheat cultivar, Zhengmai 366, was grown in pots at the Scientific and Educational Station of Henan Agricultural University during the 2010–2011 and 2011–2012 growing seasons to investigate the response of GMP particle to high temperature (HT). The experiment was performed with a completely randomized design using three replicates. Plants were grown in the natural environment and then transferred to a climate‐controlled greenhouse for two periods of HT treatments (38°C): (i) from 7 days after anthesis (DAA) to 10 DAA, and (ii) from 17 to 20 DAA, before being transferred back to the natural environment. Glutenin macropolymer particle size distribution was analyzed by laser diffraction. Results showed that heat stress led to a significant reduction in the proportion of GMP particles <10 μ m, and a concomitant increase in particles >60 μ m, yet had little effect on the number distribution of GMP particles. The proportion of GMP particles >60 μ m was positively correlated with GMP and protein concentrations, but negatively correlated with protein yield. Heat stress significantly reduced the protein and starch yields despite the fact that the proportion of GMP particles >60 μ m and the concentrations of GMP and protein all increased.\