土壤增氮对棉铃对位叶Bt杀虫蛋白含量影响及氮代谢机制

Effects of increased nitrogen on Bt protein expression and nitrogen metabolism in the leaf subtending to cotton boll

为探讨土壤增氮对Bt棉棉铃对位叶杀虫蛋白表达量影响程度及相关的氮代谢生理机制,提高Bt棉花铃期抗虫性的农学调节提供理论和技术支撑。采用裂区设计,以Bt棉常规品种泗抗1号(SK-1)、杂交品种泗抗3号(SK-3)为材料,在常规施氮量300kghm^(-2)基础上,设计施氮量分别增加25%、50%、75%、100%的处理,研究土壤增氮对Bt棉棉铃对位叶杀虫蛋白表达量影响。结果表明,2个类型品种棉铃对位叶中Bt杀虫蛋白含量均随增施氮量提高呈一直增加的特征,与对照相比,施氮量增加25%~100%,棉铃对位叶Bt杀虫蛋白增加6.1%~96.9%。氮代谢生理机制进一步表明,棉铃对位叶中可溶性蛋白含量、游离氨基酸含量、谷氨酸丙酮酸转氨酶活性和谷氨酰胺合成酶活性的变化趋势与Bt蛋白含量表现一致,而蛋白质分解关键酶(蛋白酶、肽酶)活性则随施氮量的增加呈下降趋势。叶面积指数(LAI)随增施氮量的提高而增大,而产量则随土壤氮量的增加呈先升高后降低特征,最适LAI和产量最大值均出现在常规施氮的1.25倍(375 kg hm^(-2))。综上,在常规施氮基础上适量增施氮肥有利于棉铃对位叶中Bt蛋白的合成、最适LAI的形成和产量的提高,有利于实现Bt棉丰产性和抗虫性协同表达。

The objective of this study is to explore the effect of soil nitrogen increase on the expression of insecticidal proteins in the leaf subtending to cotton boll and the related physiological mechanism of nitrogen metabolism and to provide the theoretical and technical support for agronomic regulation of Bt cotton boll stage insect resistance.A split-plot experiment was conducted.The conventional cultivar Sikang 1 and hybrid cultivar Sikang 3 were used as the experimental materials.Enhanced nitrogen fertilizer rates of increased 25%to 100%nitrogen[300(CK),375,450,525,and 600 kg hm^(-2) as pure nitrogen]were designed to study the effect on Bt protein content and nitrogen metabolic physiological in the leaf subtending to cotton boll.The results showed that the content of Bt protein in the leaf subtending to cotton boll of two types of cultivars showed a constant increase with the increase of nitrogen application rate.Compared with the control(300 kg hm^(-2)),Bt protein content in the leaf subtending to cotton boll increased by 6.1%–96.9%with the increase of 25%–100%nitrogen application.The physiological mechanism of nitrogen metabolism showed that the trend of soluble protein(SP),free amino acid(AA),and key enzymes of protein synthesis[Glutamic Oxalacetic Transaminase(GOT)and Glutamine Synthetase(GS)]in the leaf subtending to cotton boll were consistent with those of Bt protein.The activities of key enzymes of protein decomposition(protease and peptidase)decreased with the increase of nitrogen application.The leaf area index(LAI)increased with the increase of nitrogen application,while the yield increased first and then decreased with the increase of soil nitrogen.The optimum LAI and the maximum yield were both 1.25 times(375 kg hm^(-2))that of conventional nitrogen application.In conclusion,on the basis of conventional nitrogen application,an appropriate amount of nitrogen fertilizer was beneficial to the synthesis of Bt protein,the formation of the optimal LAI,and the increase of yield in the counter-position leaves of cotton boll,which was conductive to the synergistic expression of high yield and insect resistance of Bt cotton.