Abstract
Cytochrome P450 monooxygenases (P450s) of insects play crucial roles in the metabolism of endogenous and dietary compounds. Tobacco cutworm moth (Spodoptera litura), an important agricultural pest, causes severe yield losses in many crops. In this study, we identified CYP9A40, a novel P450 gene of S. litura, and investigated its expression profile and potential role in detoxification of plant allelochemicals and insecticides. The cDNA contains an open reading frame encoding 529 amino acid residues. CYP9A40 transcripts were found to be accumulated during various development stages of S. litura and were highest in fifth and sixth instar larvae. CYP9A40 was mainly expressed in the midgut and fat body. Larval consumption of xenobiotics, namely plant allelochemicals (quercetin and cinnamic acid) and insecticides (deltamethrin and methoxyfenozide) induced accumulation of CYP9A40 transcripts in the midgut and fat body. Injection of dsCYP9A40 (silencing of CYP9A40 by RNA interference) significantly increased the susceptibility of S. litura larvae to the tested plant allelochemicals and insecticides. These results indicate that CYP9A40 expression in S. litura is related to consumption of xenobiotics and suggest that CYP9A40 is involved in detoxification of these compounds.
Highlights
Cytochrome P450 monooxygenases (P450s or CYPs) represent a large enzyme family, with representatives in most organisms [1]
We explored the function of CYP9A40 by using RNA interference (RNAi)-silenced larvae that were fed with diets containing plant allelochemicals or insecticides
Herbivorous insects have evolved a variety of mechanisms to adapt to allelochemicals of host plants and insecticides
Summary
Cytochrome P450 monooxygenases (P450s or CYPs) represent a large enzyme family, with representatives in most organisms [1]. Like other P450s, CYP3 clade enzymes may have important functions in detoxification of xenobiotics and plant allelochemicals [1,4]. Outbreaks of S. litura are mainly attributed to its ability to adapt to a wide array of host plants and development of resistance to commonly applied insecticides [5,6]. To better understand the ability of S. litura to tolerate plant allelochemicals and insecticides, we became interested in the role of P450 genes of this pest [4,6]. We explored the function of CYP9A40 by using RNAi-silenced larvae that were fed with diets containing plant allelochemicals or insecticides. The results suggest a role of CYP9A40 in detoxification of plant allelochemicals and insecticides
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