RNAi in the striped stem borer, Chilo suppressalis, establishes a functional role for aminopeptidase N in Cry1Ab intoxication.
The striped stem borer, Chilo suppressalis, is a major target pest of transgenic rice expressing the Cry1Ab protein from the bacterium Bacillus thuringiensis (Bt) in China. Evolution of resistance in this pest is a major threat to the durability of Bt rice. Since Bt exerts its activity through binding to specific receptors in the midgut of target insects, identification of functional Cry1Ab receptors in the midgut of C. suppressalis larvae is crucial to evaluate potential resistance mechanisms and develop effective strategies for delaying insect resistance. In this work, we identified the putative Cry1Ab toxin-binding protein, aminopeptidase-N (APN), in the midgut of C. suppressalis by ligand blot and mass spectrometry. After cloning the full-length cDNAs encoding APN isoforms from the C. suppressalis larval midgut, we studied their spatiotemporal expression in different gut tissues and developmental stages. Furthermore, RNA interference (RNAi) against C. suppressalis aminopeptidases (CsAPNs) was employed to illustrate a functional role for CsAPNs in Cry1Ab toxicity to C. suppressalis larvae using injection and oral delivery of Stealth™ siRNA. Down-regulating the expression of CsAPNs by RNAi was closely associated with reduced susceptibility of C. suppressalis to Cry1Ab. These data provide the first direct evidence that CsAPNs participate in the mode of Cry1Ab action and may act as the functional receptor of Cry1A in C. suppressalis larvae.
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
X Y
XY
Wang
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
L X
LX
Du
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
C X
CX
Liu
Key Laboratory of Plant Resource Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China.
L
L
Gong
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China. Electronic address: lzhan@ippcaas.cn.
L Z
LZ
Han
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
Y F
YF
Peng
D000818:Animals; D001413:Bacillus thuringiensis; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D018826:CD13 Antigens / Q000378:metabolism*; D004731:Endotoxins; D055785:Gene Knockdown Techniques; D006460:Hemolysin Proteins; D019476:Insect Proteins / Q000378:metabolism*; D007305:Insecticide Resistance / Q000502:physiology*; D009036:Moths / Q000378:metabolism*; D010572:Pest Control, Biological / Q000379:methods; D030821:Plants, Genetically Modified; D034741:RNA, Small Interfering
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; D019476:Insect Proteins; D034741:RNA, Small Interfering; C030956:insecticidal crystal protein, Bacillus Thuringiensis; D018826:CD13 Antigens
Aminopeptidase N; Chilo suppressalis; Cry1Ab; Functional receptor; RNA interference