title: Next-generation transgenic cotton: pyramiding RNAi and Bt counters insect resistance.
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.
authors.affiliation: 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.
authors.forename: Mi
authors.initials: M
authors.lastname: Ni
authors.affiliation: National Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Ma
authors.affiliation: 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.
authors.forename: Xiaofang
authors.initials: X
authors.lastname: Wang
authors.affiliation: College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
authors.forename: Meijing
authors.initials: M
authors.lastname: Gao
authors.affiliation: 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.
authors.forename: Yan
authors.initials: Y
authors.lastname: Dai
authors.affiliation: 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.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Wei
authors.affiliation: 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.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.affiliation: 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.
authors.forename: Yonggang
authors.initials: Y
authors.lastname: Peng
authors.affiliation: 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.
authors.forename: Shuyuan
authors.initials: S
authors.lastname: Chen
authors.affiliation: National Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, China.
authors.forename: Lingyun
authors.initials: L
authors.lastname: Ding
authors.affiliation: National Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Tian
authors.affiliation: National Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Li
authors.affiliation: National Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, China.
authors.forename: Haiping
authors.initials: H
authors.lastname: Wang
authors.affiliation: Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Wang
authors.affiliation: Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
authors.forename: Guowang
authors.initials: G
authors.lastname: Xu
authors.affiliation: National Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, China.
authors.forename: Wangzhen
authors.initials: W
authors.lastname: Guo
authors.affiliation: College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
authors.forename: Yihua
authors.initials: Y
authors.lastname: Yang
authors.affiliation: College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
authors.forename: Yidong
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of Entomology, University of Arizona, Tucson, AZ, USA.
authors.forename: Shannon
authors.initials: S
authors.lastname: Heuberger
authors.affiliation: Department of Entomology, University of Arizona, Tucson, AZ, USA.
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Tabashnik
authors.affiliation: National Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, China.
authors.forename: Tianzhen
authors.initials: T
authors.lastname: Zhang
authors.affiliation: 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.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhu
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000235:genetics*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics; D003198:Computer Simulation; D004731:Endotoxins / Q000235:genetics; D003368:Gossypium / Q000235:genetics* / Q000276:immunology / Q000502:physiology; D006460:Hemolysin Proteins / Q000235:genetics; D019476:Insect Proteins / Q000235:genetics; D007305:Insecticide Resistance; D007306:Insecticides; D007605:Juvenile Hormones / Q000378:metabolism*; D007814:Larva; D008780:Methyltransferases / Q000235:genetics*; D009036:Moths / Q000235:genetics / Q000502:physiology*; D010572:Pest Control, Biological; D030821:Plants, Genetically Modified; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000235:genetics
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; D019476:Insect Proteins; D007306:Insecticides; D007605:Juvenile Hormones; D012330:RNA, Double-Stranded; C030956:insecticidal crystal protein, Bacillus Thuringiensis; D008780:Methyltransferases
keywords: 
  Bacillus thuringiensis
  ; 
  Helicoverpa armigera
  ; RNA interference; genetic engineering; juvenile hormone; sustainability