Qiu Lin, Hou Leilei, Zhang Boyao, Liu Lang, Li Bo, Deng Pan, Ma Weihua, Wang Xiaoping, Fabrick Jeffrey A, Chen Lizhen, Lei Chaoliang
Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
USDA-ARS, U.S. Arid Land Agricultural Research Center, Maricopa, AZ 85138, USA.
J Invertebr Pathol. 2015 May;127:47-53. doi: 10.1016/j.jip.2015.02.009. Epub 2015 Mar 6.
Bacillus thuringiensis (Bt) insecticidal crystal (Cry) proteins are effective against some insect pests in sprays and transgenic crops, although the evolution of resistance could threaten the long-term efficacy of such Bt use. One strategy to delay resistance to Bt crops is to "pyramid" two or more Bt proteins that bind to distinct receptor proteins within the insect midgut. The most common Bt pyramid in cotton (Gossypium hirsutum L.) employs Cry1Ac with Cry2Ab to target several key lepidopteran pests, including the beet armyworm, Spodoptera exigua (Hübner), which is a serious migratory pest of many vegetable crops and is increasingly important in cotton in China. While cadherin and aminopeptidase-N are key receptors of Cry1 toxins in many lepidopterans including S. exigua, the receptor for Cry2A toxins remains poorly characterized. Here, we show that a heterologous expressed peptide corresponding to cadherin repeat 7 to the membrane proximal extracellular domain (CR7-MPED) in the S. exigua cadherin 1b (SeCad1b) binds Cry1Ac and Cry2Aa. Moreover, SeCad1b transcription was suppressed in S. exigua larvae by oral RNA interference and susceptibility to Cry1Ac and Cry2Aa was significantly reduced. These results indicate that SeCad1b plays important functional roles of both Cry1Ac and Cry2Aa, having major implications for resistance management for S. exigua in Bt crops.
苏云金芽孢杆菌（Bt）杀虫晶体（Cry）蛋白在喷雾和转基因作物中对某些害虫有效，尽管抗性进化可能威胁到这种Bt应用的长期效果。延缓对Bt作物抗性的一种策略是将两种或更多种与昆虫中肠内不同受体蛋白结合的Bt蛋白“叠加”。棉花（陆地棉L.）中最常见的Bt蛋白叠加组合是使用Cry1Ac和Cry2Ab来靶向几种主要的鳞翅目害虫，包括甜菜夜蛾，即甜菜夜蛾（Hübner），它是许多蔬菜作物的严重迁飞性害虫，在中国棉花中日益重要。虽然钙粘蛋白和氨肽酶-N是包括甜菜夜蛾在内的许多鳞翅目昆虫中Cry1毒素的关键受体，但Cry2A毒素的受体仍未得到很好的表征。在这里，我们表明，甜菜夜蛾钙粘蛋白1b（SeCad1b）中与膜近端细胞外结构域（CR7-MPED）的钙粘蛋白重复序列7相对应的异源表达肽结合Cry1Ac和Cry2Aa。此外，通过口服RNA干扰，甜菜夜蛾幼虫中SeCad1b的转录受到抑制，对Cry1Ac和Cry2Aa的敏感性显著降低。这些结果表明，SeCad1b在Cry1Ac和Cry2Aa中都发挥着重要的功能作用，对Bt作物中甜菜夜蛾的抗性管理具有重要意义。
