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

• 来源期刊: 中国昆虫科学（英文版）
• 关键词: CYP321B1 cytochrome P450 monooxygenases insecticide resistance RNA interference Spodoptera litura
• 年，卷（期）: 2017,（2）
• 页码范围: 235-247
• 页数: 13页
• 语种: 英文
• DOI: 10.1111/1744-7917.12315

摘要

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 development 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 upregulated by chlorpyrifos,β-cypermethrin and methomyl with both lethal concentration at 15％ (LC15) (50,100 and 150μg/mL,respectively) and 50％(LC50) dosages (100,200 and 300μg/mL,respectively).Addition of piperonyl butoxide (PBO) significantly increased the toxicity of chlorpyrifos,β-cypermethrin and methomyl to S.litura,suggesting a marked synergism of the three insecticides with PBO and P450-mediated detoxification.RNAimediated silencing of CYP321B1 further increased mortality by 25.6％ and 38.9％ when the fifth-instar larvae were exposed to chlorpyrifos andβcypermethrin,respectively,at the LCs0 dose levels.The results demonstrate that CYP321B1 might play an important role in chlorpyrifos andβ-cypermethrin detoxification in S.litura.