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为阐明转cry1Ab/cry1Ac基因水稻对大螟Sesamia inferens(Walker)作用的生理生化机制,本研究用转cry1Ab/cry1Ac基因水稻茎秆饲喂大螟3龄和5龄幼虫,采用酶活性测定方法研究了取食转Bt水稻对大螟幼虫体内3种保护酶SOD(superoxide dismutase)、CAT(catalase)和POD(peroxidase)活性的影响。结果表明,大螟3龄幼虫在取食转基因水稻24h后SOD活性与对照相比提高了43.44%,48h后降至最低值;在取食24h后POD值达到最高值,其酶活性比对照升高了29.22%,最终在取食48h后降至最低值,并显著低于对照;在取食转基因水稻4h后,CAT活性升高了30.33%,在取食48h后,与对照相比,CAT活性降低了27.01%;5龄幼虫取食4h后SOD活性显著高于对照水平,36h后降至最低值,与对照相比,活性下降了31.62%;在取食8h后POD活性达到最高值,与对照相比,升高了73.20%,36h后酶活性降至最低值;在取食之初4h CAT活性达到最高值,与对照相比,其值升高了75.73%,在取食48h后,其活性与对照相比减少了7.55%。3龄幼虫与5龄幼虫相比,对Bt的抗性水平较低,自身防卫能力较差。结果说明,在取食初期,试虫体内保护酶活性升高,以抵御Bt毒蛋白对虫体的伤害作用,随着取食时间的延长,保护酶活性迅速降低,从而干扰虫体正常的代谢过程,导致虫体出现中毒症状,致使昆虫死亡。
In order to elucidate the physiological and biochemical mechanisms of transgenic cry1Ab / cry1Ac transgenic rice on Sesamia inferens (Walker), the 3rd and 5th instar larvae of Sesamia inferens were fed with transgenic rice plants transformed with cry1Ab / cry1Ac gene. The effects of feeding Bt on the activity of superoxide dismutase (CAT), catalase (CAT) and peroxidase (POD) in the larvae of Sesamia inferens were studied. The results showed that the SOD activity of the third instar larvae increased by 43.44% compared with the control after feeding on the transgenic rice for 24h and dropped to the lowest after 48 hours. The POD reached its highest value after 24h feeding, Which was 29.22% higher than that of the control. The activity of CAT increased to 30.33% after 4h of feeding on transgenic rice. After 48h, Compared with the control, the activity decreased by 31.62%. After 8h of feeding, the activity of POD reached the highest level, Compared with the control, the content of CAT increased 73.20% and the enzyme activity decreased to the lowest value after 36 hours. CAT activity reached the highest at 4 hours after inoculation, which increased by 75.73% compared with the control. After 48 hours , A 7.55% decrease in activity compared to the control. Compared with the 5th instar larvae, 3rd instar larvae had lower resistance to Bt and less self-defense ability. The results showed that in the initial feeding period, the protective enzyme activity of the test insects increased to resist the harm of the Bt toxic protein on the parasites. With the prolongation of the feeding time, the protective enzyme activity rapidly decreased, thereby interfering with the normal metabolism of the parasites Process, resulting in symptoms of poisoning worms, resulting in insect deaths.