Next‐generation transgenic cotton: pyramiding RNAi and Bt counters insect resistance |
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| Authors: | Mi Ni Wei Ma Xiaofang Wang Meijing Gao Yan Dai Xiaoli Wei Lei Zhang Yonggang Peng Shuyuan Chen Lingyun Ding Yue Tian Jie Li Haiping Wang Xiaolin Wang Guowang Xu Wangzhen Guo Yihua Yang Yidong Wu Shannon Heuberger Bruce E Tabashnik Tianzhen Zhang Zhen Zhu |
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| Affiliation: | 1. State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China;2. National Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, China;3. College of Plant Protection, Nanjing Agricultural University, Nanjing, China;4. Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China;5. Department of Entomology, University of Arizona, Tucson, AZ, USA |
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| Abstract: | Transgenic crops producing insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) are extensively cultivated worldwide. To counter rapidly increasing pest resistance to crops that produce single Bt toxins, transgenic plant ‘pyramids’ producing two or more Bt toxins that kill the same pest have been widely adopted. However, cross‐resistance and antagonism between Bt toxins limit the sustainability of this approach. Here we describe development and testing of the first pyramids of cotton combining protection from a Bt toxin and RNA interference (RNAi). We developed two types of transgenic cotton plants producing double‐stranded RNA (dsRNA) from the global lepidopteran pest Helicoverpa armigera designed to interfere with its metabolism of juvenile hormone (JH). We focused on suppression of JH acid methyltransferase (JHAMT), which is crucial for JH synthesis, and JH‐binding protein (JHBP), which transports JH to organs. In 2015 and 2016, we tested larvae from a Bt‐resistant strain and a related susceptible strain of H. armigera on seven types of cotton: two controls, Bt cotton, two types of RNAi cotton (targeting JHAMT or JHBP) and two pyramids (Bt cotton plus each type of RNAi). Both types of RNAi cotton were effective against Bt‐resistant insects. Bt cotton and RNAi acted independently against the susceptible strain. In computer simulations of conditions in northern China, where millions of farmers grow Bt cotton as well as abundant non‐transgenic host plants of H. armigera, pyramided cotton combining a Bt toxin and RNAi substantially delayed resistance relative to using Bt cotton alone. |
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| Keywords: | genetic engineering RNA interference
Bacillus thuringiensis
juvenile hormone
Helicoverpa armigera
sustainability |
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