Abstract: 【Aim】 Cry resistance developed in target pests has been caused by the sustainable planting of Bt crops. Previous work indicated that the down-regulation of white gene is tightly linked to Cry1Ac resistance in Plutella xylostella, and Pxwhite and ATP-binding cassette transporter ABCG1 belong to ABCG subfamily, so we predict that the similar change of ABCG1 gene expression may be associated with the Cry1Ac resistance in Helicoverpa armigera. 【Methods】 The open reading frame (ORF) of HaABCG1 was cloned from H. armigera, the subcellular localization of HaABCG1 protein in TnH5 cells was detected by constructing expression vector of HaABCG1, the ABCG1 protein as the receptor of Cry1Ac toxin with cytotoxicity of Bt toxin was confirmed by cytotoxicity tests, and whether the down-regulation of HaABCG1 could decrease the susceptibility of H. armigera to Cry1Ac toxin was confirmed by RNA interference (RNAi) and bioassay. 【Results】 The open reading frame of HaABCG1 is 1 896 bp, encoding 631 amino acid residues with the predicted molecular weight of 69.63 kD. HaABCG1GFP is mainly localized on the nuclear membrane and endoplasmic reticulum of TnH5 cells. RNAi-mediated suppression of HaABCG1 expression did not decrease the susceptibility of H. armigera to Cry1Ac toxin, and the body weight change had no significant difference between the experimental group and the control group reared on artificial diet containing 0.05 μg/mL Cry1Ac for 3 d after RNAi. HaABCG1 protein did not mediate the cytotoxicity of Cry1Ac to TnH5 cells, and it was neither the receptor of Cry1Ac, nor the receptor of Cry1Ca, Cry2Aa or Cry1Fa. 【Conclusion】 The results suggest that the down-regulation of HaABCG1 is not associated with Cry1Ac resistance in H. armigera, and HaABCG1 is not the receptor of Cry1Ac. This is the first report that ABCG1 gene is not involved in the Cry1Ac resistance of H. armigera.

Key words: Helicoverpa armigera, ABCG1, Cry1Ac, Bt toxin receptor, subcellular localization, Bt resistance