Effect Of Rare Earth On The Quality Of Wheat And Its Induced Protein Identification

After 40 years of continuing research and development, the study of technology and basic theory of rare earth elements in agriculture achieved remarkable results, and it was made clear that the suitable concentration of rare earth had the biological effect of increasing yield, improving quality and enhancing resistance on crop, and the application of rare earth in agriculture had achieved remarkable social and economic benefits. But in recent years, due to the mechanism research of rare earth moved slowly, it had made development of rare earth in agriculture gradual. Wheat was one of the main food crops in China, and its yield and quality was not only determined by genetic traits itself, but also affected by the environmental condition and cultivation measures. Due to the improper measures of cultivation and other reasons, it usually appeared that quality stability of the commodity wheat that some high quality varieties produced was poor, and it was no coordination between quality traits.In this paper, field planting and laboratory hydroponics method were dopted, through the related physiological indexes, wheat grain quality detection and analysis, twodimensional electrophoresis, and mass spectrometer, it was studied that effects of rare earth on the physiological indexes, yield and quality with different gluten types in wheat, which provided cultivation technology measures for improving wheat quality. In addition, it was studed that the biological effect of different rare earth complexes and reaction mechanism of wheat on La, and differential proteins responsing to La at 0.5 mmol/L and 5.0 mmol/L concentration, and some proteins being related to the biological effects and resistance of La were found.The main results were listed as follows:1.The effects of different rare earth complexes on physiological characteristics in wheatIn order to facilitate the absorption by plant, rare earth oxides were usually changed into ions or complexes form in agricultural applications.In this study, it was selected Cl-,NO3-, glycine as ligand of La and Nd, and the rare earth concentration was treatment concentration of rare earth complexes, and the wheat was treated by foliar spraying at seedling stage.Three kinds of lanthanum complexes increased the chlorophyll content in wheat at 0.5-1.5mmol/L of La3+; under different Lanthanum complex treatment, the changing trend of nitrate reductase activity of the same variety was accordant, so La was the main effect factor.The suitable complexes concentration of La with NO3- and Cl- could improve the activity of SOD in wheat, but the activity of POD was shown reduce.Under three Nd complexes treatment, chlorophyll content showed a decreasing trend, and in thetreatment of the ligand NO3-at 0.5-2.0mmol/L of Nd3+, nitrate reductase activity of two varieties was enhanced significantly. The complex of Nd with glycine could enhance the SOD activity, and different Nd complexes had the activation effect of POD enzyme activity.2.Effect of La on sulfhydryl compounds and soluble protein in wheatThe wheat seeds were treated with La stress, and 200 cultivars(lines) were screened by taking the final germination rate as index. Zhou8425 B, Yanzhan4110, Yuzhan9804,Annong9192 and Yumai36 had stronger tolerance to La, and Wanmai41, Yuzhan1, Annong90202, Wanmai46, Wanmai19 and Annong8559 were more sensitive to La.The Zhou8425 B and Wanmai41 being treated with different concentration La3+, it was detected total thiol, protein thiol, non- protein thiol content and soluble protein in the leaves and roots. The results showed that the tolerant variety reduced transportation of La to the shoots of plants by non-protein thiol synthetized in root complexing La, so improved tolerance to La. When the sensitive cultivar was stressed by La, protein thiol content decreased, and there were more amount of La transported to the leaves, so the expression of protein thiols increased in leaves, and stress effect of high concentration La might be more prominent in the roots, so the tolerance to La decreased.3.Effects of La on physiological indexes of wheat with different gluten typesThe wheats with different gluten types were planted in the field, and sprayed La Cl3 at jointing stage and filling stage. At La treatments of 0.5 ~ 1.5mmol/L, chlorophyll content in different growth period showed various degree increase compared with the control. SOD activity of Wanmai33 leaf was activated effects only after the two spraying accumulation,while that of Yangmai158 and Wanmai48 were activated after spraying one time, and MDA content decreased, that suggested Yangmai158 and Wanmai48 was more sensitive to La. La could enhance the effect of nitrate reductase activity in leaves at flowering stage, and the most suitable concentration range of La on nitrate reductase and yield of wheat with different gluten types were different.4.Effects of La3+on yield and quality traits of wheat with different gluten typesThe wheat grains in field experiment were harvested, and were determined indexes of yield, nutritional quality and processing quality. Spraying 0.5-1.5 mmol/L La3+ could increase the yield of wheat and improve its quality for different end uses, and La3+concentration of the flour was in a secure level. Moreover, the effects of La3+on the quality traits of wheat with different gluten types were different.For strong gluten type variety Wanmai 33, spraying 0.5-1.5 mmol/L La3+increased protein content and carotenoid content,decreased LOX and PPO activity, thus increased the nutritional value of flour and prolonged storage period. Different La3+ concentration treatments significantly reduced flour water absorption, but it still could meet the need of high-gluten flour. The 1.5 mmol/L La3+increased water-soluble pentosan, and had a certain effect on improving the quality.For medium gluten type variety Yangmai 158, spraying 0.5-1.5mmol/L La3+ increased starch pasting peak viscosity, thus improved the flour processing quality. LOX and PPO activity increased, and carotenoid content reduced, which whitened the flour and improved commodity nature, but the security storage period was shortened. For weak gluten type variety Wanmai 48, spraying 0.5-1.5mmol/L La3+ significantly increased wet gluten content.Peak viscosity increased significantly and LOX activity decreased obviously at 0.5 mmol/L La3+, and PPO activity and carotenoid content increased significantly at 1.0 mmol/L La3+.The nutritional value increased at low La3+ concentration but the flour color was yellowish.Flour water absorption of all treatments of La3+reduced significantly, stable period decreased, and total pentosan reduced at 1-1.5 mmol/L La3+, thus improved the biscuit processing quality.5.Effect of La on wheat proteomeThe wheats were treated by 0.5, 5.0mmol/L La, and fresh leaf tissue were extracted,and the differential protein spots were obtained by 2-DE, and were identified by mass spectrometry of MALDI-TOF-MS. After treatment with 0.5mmol/L La3+, 27 protein spots abundance of wheat leaves changed up to 1.2 times in comparison with the control, of which 18 protein spots were up-regulated and 9 protein spots were down-regulated expression. After treatment with 5.0mmol/L La3+, 34 protein spots abundance changed up to 1.2 times in comparison with the control, of which 14 protein spots were up-regulated and 20 protein spots were down-regulated expression. And differential expression of proteins was the molecular basis of the biological effect of La in proper concentration and high concentration.15 differential protein spots were successful matched by mass spectrometry. At the La concentration was 0.5 mmol/L, there had been stimulating effect that ribulose-1,5-bisphosphate carboxylase/oxygenase and chloroplast fructose-bisphosphate aldolase increased,and enzyme activity enhanced. Meanwhile, it also appeared that the prohibitin expression decreased. So La at this concentration stimulated the growth of wheat mainly, and enhanced photosynthesis and accelerated glucose metabolism, which was conducive to grain protein and starch accumulation, and was beneficial to yield improvement and quality formation. At the La concentration was 5.0mmol/L, there hadbeen expression of protein related to plant stress. The expression of catalase decreased, so the plant had been under stress. Expression intensity of plant photosynthesis related enzyme of Chlorophyll a-b binding protein, ribulose bisphosphate carboxylase and ferredoxin were decreased, and accompanied by the ATP synthase and thiazole biosynthetic enzyme expression intensity increasing, that showed that the plant growth were in the main role of the inhibition.