PxCAD1 与Cry1Ac 蛋白混合物对小菜蛾生长发育及体内酶活性的影响

【Purpose】The PxCAD1 peptide segment can significantly enhance the insecticidal activity of Cry1Ac. Exploring the effects of its mixture with Cry1Ac on the biology and in vivo enzyme activities of target insects is of great significance for clarifying its synergistic mechanism. 【Methods】Using the leaf dip method, the third-instar larvae of Plutella xylostella were fed with the mixed protein of the PxCAD1 peptide segment and the Cry1Ac toxin, and the mortality rate, pupation rate and eclosion rate of Plutella xylostella were observed and counted, and the changing trends of carboxylesterase, glutathione -S-transferase, total protease and trypsin-like protease in the larvae of Plutella xylostella were measured. 【Results】Compared with the control, the mortality rate of the larvae in the treatment group was significantly increased, the pupation rate was decreased, and the eclosion rate was significantly reduced; after the third-instar larvae fed on the mixed protein of the PxCAD1 peptide segment and the Cry1Ac toxin for 24 h and 48 h, the activity of carboxylesterase was significantly increased and significantly decreased at 72 h, the activity of glutathione -S-transferase was significantly increased at 24 h and significantly decreased at 48 h, and there was no significant difference at 72 h, while the activity of total protease was only significantly lower than that of the control at 72 h, and the activity of trypsin-like protease had no significant change at each time point. 【Conclusion】PxCAD1 not only has a significant synergistic effect on Cry1Ac, but also has an adverse effect on the growth and development of the larvae of Plutella xylostella and the activities of carboxylesterase, glutathione -S-transferase and total protease in vivo. These results will be helpful for further research on the synergistic mechanism of midgut receptor proteins on Cry1Ac.

【目的】 PxCAD1 肽段可显著增强Cry1Ac 的杀虫活性，探究其与Cry1Ac 混合物对靶标昆虫生.物学及体内酶活性的影响对明确其增效机制具有重要意义。【方法】采用叶片浸渍法，以PxCAD1 肽段.与Cry1Ac 毒素的混合蛋白饲喂小菜蛾Plutella xylostella 3 龄幼虫，观察并统计小菜蛾死亡率、化蛹率和.羽化率，并测定小菜蛾幼虫体体内羧酸酯酶、谷胱甘肽-S-转移酶、总蛋白酶和类胰蛋白酶的变化趋势。.【结果】与对照相比，处理组幼虫的死亡率显著升高，化蛹率减少，羽化率显著降低；3 龄幼虫在取食.PxCAD1 肽段与Cry1Ac 毒素混合蛋白24 h 和48 h 后，羧酸酯酶活性显著升高，72 h 显著降低，谷胱甘肽-S-.转移酶活性在24 h 显著升高，48 h 显著降低，72 h 则无显著差异，而总蛋白酶活性仅在72 h 显著低于对.照，类胰蛋白酶活性在各时间点无显著变化。【结论】PxCAD1 不仅对Cry1Ac 具有显著增效作用，同时.对小菜蛾幼虫的生长发育及体内羧酸酯酶、谷胱甘肽-S-转移酶及总蛋白酶的活性产生不利影响。该结果.将有助于进一步研究中肠受体蛋白对Cry1Ac 的增效机制。