盐碱土壤转Bt基因棉花外源蛋白表达量时空变化及对抗虫性的影响

盐碱地是潜在的可利用耕地资源,但土壤盐碱化严重制约了农业生产的可持续发展。基于棉花机械化程度低、劳动力成本和生产资料投入剧增、比较效益下降和实施粮食生产安全战略等因素影响,我国长江流域和黄河流域棉花面积锐减,种植区域向内陆盐碱旱地或滨海盐碱地转移,但目前针对盐碱地转Bt基因棉种植可能带来的生态安全性问题研究甚少,正成为国内外研究的焦点和热点。伴随着棉花向盐碱地大面积转移种植趋势,检测盐胁迫是否影响转基因抗虫棉抗虫性,明确其影响程度,直接关系到转基因抗虫棉种植的安全性,也是目前抗虫棉扩大生产中迫切需要解决的问题。以非转基因棉花为对照,分别在低盐、中盐和高盐土壤种植的棉花的苗期、蕾期和花铃期采样,室内测定了转Bt基因棉花叶片对棉铃虫幼虫校正死亡率和外源蛋白表达量。研究结果发现盐分胁迫下转Bt基因棉花苗期叶片对棉铃虫幼虫校正死亡率下降了9.22%—47.46%,蕾期下降了31.61%—45.42%,花铃期下降了3.59%—18.52%;土壤盐分显著降低了转Bt基因棉花叶片中外源蛋白的表达量,苗期功能叶外源蛋白表达量下降了7.66%—29.86%;蕾期下降了3.77%—36.85%;花铃期下降了18.13%—41.02%;相关性分析表明,盐分胁迫条件下转Bt基因棉花叶片中外源蛋白表达量与其对棉铃虫抗性程度存在正相关关系。结果表明,盐碱土壤显著降低了转Bt基因棉花叶片外源杀虫蛋白表达量,从而导致转Bt基因棉花叶片对棉铃虫的抗虫性下降。研究土壤盐分对转Bt基因棉花对棉铃虫的影响及其作用机制,可为建立盐碱地转Bt基因棉花田害虫综合防控技术体系、转Bt基因棉花环境安全评价及转Bt基因棉安全管理提供依据。

The effects of temporal and spatial variation of exogenous protein of transgenic Bt cotton to insect resistance in saline-alkali soil

Saline-alkali land is a potentially exploitable reserve cultivated land resource, but it severely restricted the sustainable development of agricultural production. Owing to some factors such as the decreasing degree of cotton mechanization, increasing input of labor cost and production goods, declining comparative benefits, and implementing the strategy of food security, the cotton area in the Yangtze River and Yellow River is declining sharply, and the planting area is transferred to Binhai saline-alkali lands. Since the study of ecological security of planting Bt cotton in saline-alkali land is rare, it became the focus of many research studies worldwide. Whether the resistance of transgenic Bt cotton to cotton bollworm has been affected remains to be elucidated. Resistance is directly related to the environment safety of transgenic Bt cotton; therefore, there is an urgent need to solve the problems in cotton production. With the non-transgenic cotton as the control, we measured the corrected mortality of transgenic Bt cotton to cotton bollworm larvae and the contents of exogenous protein of transgenic Bt cotton that was planted in the low-, medium-and high-salt soil at seedling, budding, and flowering and bolling stages, respectively. The results showed that at the seedling, budding, and flowering and bolling stages of transgenic Bt cotton in low salt stress, the correction mortality of transgenic Bt cotton planted in the medium-and high-salt soil to cotton bollworm larvae decreased by 9.22%-47.46%, 31.61%-45.42%, and 3.59%-18.52%, respectively. Over the same period of Bt cotton, soil salinity significantly inhibited the expression of Bt protein in cotton leaves and decreased by 7.66%-29.86%, 3.77%-36.85%, and 18.13%-41.02% at seedling, budding, and flowering and bolling stages, respectively. There is a significant positive correlation between the efficiency of insect resistance of transgenic Bt cotton to cotton bollworm larvae and Bt protein content. Therefore, soil salinity levels inhibited the exogenous protein expression of transgenic Bt cotton, which led to the decreased resistance of transgenic Bt cotton on cotton bollworm. The present study on the effects and mechanisms of soil salinity on the influence of transgenic Bt cotton to cotton bollworm can provide a comprehensive basis for establishing Bt cotton pest prevention and control technology system, environmental safety evaluation, and safety management in soil salinity in Bt cotton fields.