Effects Of Accumulation Pattern Of Seed Storage Protein On Rice Quality

Rice(Oryza sativa L.),as an important food crop,is the main food source on which half of the world’s population depends,and it is also the main source of protein.Compared with other plant proteins,the storage protein of rice seeds is a rare high-quality protein.Generally believed that the crude protein content of rice eating quality traits such as negative correlation,as the main problems limiting rice protein quality improvement.However,there is no direct evidence for the relationship between rice protein content,composition,accumulation forms and rice quality.First,according to rice seed appearance,protein content and SDS-PAGE polyacrylamide gel electrophoresis analysis,and from more than 100 rice varieties,we chosed two rice varieties with different protein components and contents 16-17(glutelin has obvious precursor polymer,with high contents)and 16-20(glutelin doesn’t have obvious precursor polymer,with low contents)was used in this experiment.And the hydroponic test is set for the processing of CK(Nitrogen: 2800μmol/L,Sulfur: 80μmol/L),N(Nitrogen: 3640μmol/L,Sulfur: 80μmol/L),S(Nitrogen: 2800μmol/L,Sulfur: 260μmol/L)and N+S(Nitrogen: 3640μmol/L,Sulfur: 260μmol/L).The purpose of the study is to reveal the effects of combined application of nitrogen and sulfur on the accumulation of seed protein during rice growth,including changes in the content,composition and accumulation form of rice storage protein,as well as the impact of these changes on rice quality,analysis and discussion of rice storage The relationship between protein and rice quality.The main results are as follows:1.At different N,S with the composition and application conditions of storage protein accumulation configuration of rice seeds in a significant change occurs,and very different between different species.With the addition of N,S and N+S treatment,the crude protein content was increased,the total protein content of 16-17 has increased by 0.15%-1.14%,and the total protein content of 16-20 was significantly increased by 2.35%-2.73%;At the same time,the absolute content of each component of the protein also changed,such as N,S and N+S three treatments made 16-17 gliadin increased by 9.75%,4.21% and 4.67% compared with the control group,gluten The content of N,S and N+S increased by 3.92%,7.38% and 12.92% respectively under three treatments;for 16-20,the gluten content under S and N+S treatments increased significantly by 17.72% and 29.38% compared with the control,The prolamin increased significantly by 3.73% under N+S treatment,while the globulin content under the three treatments N,S and N+S decreased significantly by 2.86%,3.78% and 3.69%,albumin at N,S When treated separately,it was significantly reduced by 2.52% and 2.56%.2.Treatment with increased S changed the relative content of the two subunits of gluten and increased the accumulation of gluten precursors of 57 kDa and gluten aggregates above 57 kDa.According to the extracted gluten map and two-dimensional electrophoresis map,the glutenin subunits and the protein components with relative molecular weights of 45 k D-116 k D showed obvious differences.At the same time,the changes in thiol content and disulfide bond content are basically consistent with this change trend.It is speculated that this difference in protein accumulation may be due to the combination of sulfhydryl-containing protein subunits in rice through intermolecular and intramolecular disulfide bonds to form a large Caused by molecular polymers.3.Different N and S combined application treatments have different effects on different varieties of rice quality traits.The change of the two varieties in terms of milling quality is not obvious;in terms of appearance quality,the chalkiness of the 16-17 varieties decreased by 18%,18.34% and 17.34% under the three treatments of N,S and N+S,Chalkiness was also significantly reduced by 17.6%,17.81% and 17.36%;there was no significant change in chalkiness and chalkiness of 16-20 varieties under different N and S combined treatments,but the chalkiness rate of 16-20 varieties was in S And N+S decreased by 2% and 3% respectively.In terms of cooking quality,under the three treatments of N,S and N+S,the amylose content of the two varieties of 16-17 and 16-20 decreased,respectively,by 1.29%,0.04%,0.47% and 0.48%,2.6%,2.07%.In terms of nutritional quality,there was no significant difference in 16-17 seed protein changes,while 16-20 seed protein content increased significantly by 2.35%,2.67% and 2.73% under N,S and N+S treatments.In general,the combined application of N and S has little effect on the milling quality traits of the two tested varieties,but it is conducive to the improvement of the appearance and taste quality of the two varieties of rice,and makes the nutritional quality of 16-20 significant increase.In summary,different N and S combined treatments can change the accumulation amount and form of thiol-containing protein components.Especially under S-rich conditions,more sulfhydryl groups and disulfide bonds are formed during protein accumulation,and the degree of polymerization between thiol-containing protein subunits is changed by disulfide bonds to form gluten polymers of different molecular weights,so that the accumulation morphology of the protein changed obviously,which in turn caused other related quality traits of rice to change.