Abstract: The efficient and stable expression of exogenous insecticidal genes in transgenic cotton is the key of transgenic cotton application. In order to compare the insect-resistant effect of transgenic cotton under different seeds purity, two transgenic varieties GK12 and SGK321 were mixed with non-genetically modified cotton seeds in eight different proportion for evaluating insecticidal protein expression level, the molecular detection and indoor hygiene tests showed that with the decline in the purity of insect resistance, cotton bollworm damage level gradually increased, corrected mortality of H. armigera larvae decreased, varieties of insect-resistant capacity declined. The field experiments indicated that with the decline of the insect resistant purity, boll number reduced, the number of empty fruit branches increased, which ultimately led to a sharp decline in production, and thus gave rise to the so-called “Bt cotton is not insect resistant”. In conclusion, the decline of seed purity had significant effection on insect resistance and cotton yield. In order to ensure high yield, the purity of transgenic insect-resistant cotton should be higher than 97%.

Key words: insect resistance, yield, seed purity, transgenic cotton

摘要： 外源杀虫基因能否在转基因棉花中高效、稳定表达是影响转基因棉花应用前景的关键。本文从转基因棉花杀虫蛋白表达水平出发,通过在转基因棉花品种的种子中混杂非转基因棉花品种的种子,研究不同品种纯度的转基因棉花杀虫蛋白表达水平对转基因抗虫棉的抗虫性影响。本研究选用2个转基因抗虫棉品种GK12和SGK321,设置了8种混杂比例,通过分子检测和室内生测试验表明,随着抗虫纯度的下降,棉铃虫危害等级升高,幼虫校正死亡率下降,品种抗虫能力下降;从田间实验结果来看,随着抗虫纯度的下降,铃数减少,空果枝数增多,最终致使产量大幅下降,从而出现所谓的“抗虫棉不抗虫”现象。结果显示,转基因抗虫棉品种抗性纯度至少要达到97%,才可以保证产量不至于损失太大。

关键词: 抗虫性, 产量, 种子纯度, 转基因棉花