Identification of a novel cytochrome P450 CYP321B1 gene from tobacco cutworm （Spodoptera litura） and RNA interference to evaluate its role in commonly used insecticides

• Published in: 昆虫科学：英文版 2017, Vol.24 (2), p.235-247
• Main Author: Rui-Long Wang Keyan Zhu-Salzman Scott R. Baerson Xiao-Wei Xin Jun Li Yi-Juan Su Ren-Sen Zeng
• Format: Article
• Language: English
• Subjects: P450基因; RNA干扰作用; 基因鉴定; 杀虫剂; 烟草夜蛾; 细胞色素P450; 评价; 高效氯氰菊酯
• ISSN: 1672-9609; 1744-7917

Insect cytochrome P450 monooxygenases （CYPs or P450s） play an important role in detoxifying insecticides leading to resistance in insect populations. A polyphagous pest, Spodoptera litura, has developed resistance to a wide range of insecticides. In the present study, a novel P450 gene, CYP321B1, was cloned from S. litura. The function of CYP321B1 was assessed using RNA interference （RNAi） and monitoring resistance levels for three commonly used insecticides, including chlorpyrifos, β-cypermethrin and methomyl. The full-length complementary DNA sequence of CYP321B1 is 1814 bp long with an open reading frame of 1 488 bp encoding 495 amino acid residues. Quantitative reverse-transcriptase polymerase chain reaction analyses during larval and pupal develop- ment indicated that CYP321B1 expression was highest in the midgut of fifth-instar larvae, followed by fat body and cuticle. The expression of CYP321B1 in the midgut was up- regulated by chlorpyrifos,β-cypermethrin and methomyl with both lethal concentration at 15% （LC15） （50, 100 and 150 μg/mL, respectively） and 50%（LC50） dosages （100,200 and 300μg/mL, respectively）. Addition of piperonyl butoxide （PBO） significantly increased the toxicity ofchlorpyrifos,β-cypermethrin and methomyl to S. litura, suggesting a marked synergism of the three insecticides with PBO and P450-mediated detoxification. RNAi- mediated silencing of CYP321B1 further increased mortality by 25.6% and 38.9% when the fifth-instar larvae were exposed to chlorpyrifos and β-cypermethrin, respectively, at the LCso dose levels. The results demonstrate that CYP321B1 might play an important role in chlorpyrifos and β-cypermethrin detoxification in S. litura.