昼夜变温下高温对Bt棉铃壳杀虫蛋白及氮代谢生理的影响

Effects of High Alternating Day and Night Temperature Conditions on the Boll Wall's Bt Protein Content and Nitrogen Metabolic Physiology in Bt Cotton

【目的】确定在昼夜变温条件下,高温逆境对转基因棉花铃壳中杀虫蛋白含量的影响及相关生理特征。[方法]以大面积推广应用的Bt棉常规品种泗抗1号和杂交种泗抗3号为材料,于2011―2012年在扬州大学遗传生理重点实验室,用盆栽棉花在人工气候室设计昼夜变温(39/27℃)条件下高温持续4~10 d胁迫,研究铃壳中Bt蛋白含量、氮代谢相关物质和关键酶活性的变化特征。【结果】铃壳中Bt杀虫蛋白含量随胁迫时间的延长而降低。与对照(32/25℃)相比,胁迫7 d后铃壳中Bt杀虫蛋白开始急剧下降。2011年度常规种泗抗1号和杂交种泗抗3号分别下降了18.44%和14.82%;2012年分别下降了19.07%和15.26%。铃壳中Bt杀虫蛋白下降同时,其游离性氨基酸含量和蛋白酶活性明显上升,而可溶性蛋白含量和GPT活性则显著下降。【结论】昼夜变温下高温引起铃壳中蛋白质合成减弱,分解加剧,导致蛋白质含量下降(包括Bt蛋白含量下降),从而引起抗虫性降低。

[Object]In this study,the objective was to study changes in the boll wall's Bt protein concentration and related physiological characteristics under high alternating day and night temperature conditions in Bt cotton.[Method]The experiments were conducted at the Key Laboratory of Genetics and Physiology,Yangzhou University during the 2011-2012 cotton growing seasons.The conventional Bt cotton cultivar Sikang-1 and hybrid cultivar Sikang-3 were used as the test materials.The boll wall's Bt protein content and nitrogen metabolic physiology were investigated under high temperatures(39/27℃,day/night)for 4-10 d at the peak boll stage.[Result]The Bt protein content in the boll wall decreased as the stress time increased.Compared with the control(day/night,32/25℃),the Bt protein content in the boll wall decreased significantly at 7 d under the high temperature stress.The values for cultivars Sikang-1 and Sikang-3 decreased by 18.44%and 14.82%,respectively,in 2011,and by 19.07%and 15.26%,respectively,in 2012.As the Bt toxin content decreased,the boll wall's free amino acid content and protease activity increased,while the soluble protein content and GPT(Glutamic-pyruvic transaminase)activity decreased significantly.[Conclusion]The reduction in Bt protein synthesis and increase in the insecticidal protein degradation at the boll wall under high temperatures caused a reduction in the protein content,including the Bt protein content,which resulted in a reduction in insect resistance.