Combined Effects of Nitrogen and Sulphur Fertilization on Content and Size Distribution of Glutenin Macropolymer in Wheat Grain

Abstract

The content and size distribution of glutenin macropolymer (GMP) play key roles in grain quality of wheat (Triticum aestivum L.).The aims of this study were to analyse the relationship between the content and size distribution of GMP and evaluate combined effects of nitrogen and sulphur fertilization on the content and size distribution of GMP in wheat grain.In the study,Shannong 15 was used in a field experiment with three nitrogen (N) application levels (120,240,and 360 kg ha-1) and three sulphur (S) application levels (0,60,and 90 kg ha-1).HMW-GS and LMW-GS were firstly separated using the sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE),and each of the subunits was then extracted before quantitative measurement by colorimetric analysis.The result showed that,in certain ranges,contents of GMP,HMW-GS,and LMW-GS were significantly increased with more application of nitrogen fertilizes.The increasing application of sulphur showed no significant effect on GMP content,but reduced contents of HMW-GS and D-LMW-GS and promoted contents of B-LMW-GS and C-LMW-GS.The content of small GMP particle (diameter less than 12 μm) was significantly reduced with the increase of nitrogen and sulphur fertilization,and the content of large GMP particle (diameter no less than 12 μm),tended to increase with the increase of nitrogen application and sulphur application.However,the distribution of GMP particle number was not affected by the nitrogen and sulphur treatments.According to correlation analysis,C-LMW-GS content was negatively correlated with the content of small GMP particle.These results suggested that increasing nitrogen application had the effect on the absolute content of GMP,while increasing sulphur application affected relative content of GMP.Nitrogen and sulphur fertilization have positive modulation on the content of large GMP particle,and C-LMW-GS plays an important role in the development of large GMP particle.