涝渍对Bt棉棉蕾杀虫蛋白表达含量及氮代谢影响

以Bt棉常规种泗抗1号和杂交种泗抗3号为材料,于盛蕾期设计不同程度涝渍(土壤持水量为最大持水量的90%、100%,渍水2 cm)胁迫4 d以及土壤持水量为最大持水量90%逆境下持续胁迫24~120 h的试验,探讨棉蕾中Bt杀虫蛋白表达量变化及相关氮代谢生理机制。结果表明,土壤不同涝渍程度影响棉蕾Bt蛋白含量。土壤持水量为最大持水量的90%、100%和渍水2 cm处理胁迫后,常规种泗抗1号棉蕾中Bt蛋白含量分别下降36.5%、42.1%和51.4%,杂交种泗抗3号分别下降19.2%、57.2%和64.5%。90%的土壤持水量持续胁迫96 h使棉蕾Bt蛋白含量开始显著下降,泗抗1号和泗抗3号分别下降20.8%和17.6%。随着胁迫时间延长下降幅度增大。不同涝渍程度或水渍持续胁迫条件下,棉蕾中可溶性蛋白含量,硝酸还原酶(NR)、谷氨酸草酰乙酸转氨酶(GOT)、谷氨酸丙酮酸转氨酶(GPT)、谷氨酰胺合成酶(GS)和谷氨酸合成酶(GOGAT)活性下降,游离性氨基酸含量,肽酶、蛋白酶活性增加。说明涝渍逆境下,棉蕾中蛋白质合成能力下降、分解能力增强,引起可溶性蛋白包括Bt杀虫蛋白含量下降,导致棉蕾抗虫性下降。

Effects of Waterlogging on Bt Protein Content and Nitrogen Metabolism in Square of Bt Cotton

Using Bt cotton conventional cultivar Sikang 1 and hybrid Sikang 3 as test materials, the experiments of water stress at different levels (relative soil water capacity at 90%, 100%, and 2 cm waterlogging above the soil surface respectively) and 90% soil water capacity remained 24–120 hours were conducted to investigate the square Bt insecticidal protein expression and nitrogen metabolism in bud developmental stage. The soil waterlogging treatments with three levels reduced the square Bt insecticidal protein content by 36.5%, 42.1%, and 51.4% for conventional cultivar Sikang 1 and by 19.2%, 57.2%, and 64.5% for hybrid Sikang 3, respectively. The continuous stress of 96 h in the 90% soil water capacity treatment decreased the square Bt insecticidal protein content significantly, which was 20.8% for Sikang 1 and 17.6% for Sikang 3, the longer the stress sustained, the more the Bt toxin content declined. The soluble protein content, NR, GOT, GPT, GS, and GOGAT activities decreased, and the free amino acids content, peptidase and protease activities increased under different levels of soil waterlogging and continuous stress of 90% soil water capacity stress. Therefore, the reduced protein synthesis ability, and enhanced protein degradation ability may decrease the square soluble protein content including Bt insecticidal protein content, resulting in reduction of the square insect resistance.