Transcription profiling of two cytochrome P450 genes potentially involved in acaricide metabolism in citrus red mite Panonychus citri

• This is the first report of two full-length P450 genes from Panonychus citri.
• The two P450s are over-transcribed in larval stages and resistant strain.
• CYP4CF1 is significantly induced by pyridaben.
• CYP4CL2 is induced by abamectin, azocyclotin, and pyridaben.
• The activity of cytochrome P450 (general oxidase) increases after acaricides exposures.

Acaricide resistance in citrus red mite, Panonychus citri (McGregor), has been a growing problem in the management of this pest globally. As a member of main detoxification enzymes, cytochrome P450 monooxygenases (P450s) play important roles in the development of acaricide resistance in arthropods. In this study, two novel P450 genes (named CYP4CF1 and CYP4CL2) were cloned from P. citri. CYP4CF1 and CYP4CL2 had open reading frames of 1527 and 1758 nucleotides encoding 508 and 585 amino acids, respectively. The putative proteins shared 34% identity with each other. Phylogenetic analysis showed that CYP4CF1 and CYP4CL2 were most closely related to CYP4CF2 and CYP4CL1 from Tetranychus urticae, respectively. The transcriptional activities of CYP4CF1 and CYP4CL2 were also investigated. Quantitative RT-PCR revealed that the expression level of CYP4CF1 was increased after induction by pyridaben, while that of CYP4CL2 increased after induction by abamectin, azocyclotin, pyridaben, and spirodiclofen. The mRNA levels of both CYP4s were significantly higher in larval stages, as well as in a field resistant population (BB) than in laboratory susceptible strain (LS). The identification of this detoxification enzyme activity showed that the activity of P450s was higher than the control after exposure to azocyclotin, pyridaben and spirodiclofen. The results suggested that two CYP4 genes might play distinct but significant roles in larvae of P. citri. The results further indicate that CYP4CF1 is associated with pyridaben metabolism, while CYP4CL2 may be involved in detoxification of abamectin, azocyclotin, pyridaben, and spirodiclofen.

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