Transcriptome-Wide Identification of Cytochrome P450s and GSTs from Spodoptera exigua Reveals Candidate Genes Involved in Camptothecin Detoxification

Abstract

The application of camptothecin (CPT) and its derivatives to control insect pests has generated significant interest. This study investigated the enzymatic response of cytochrome P450 monooxygenase (CYP) and glutathione S-transferase (GST) genes in the fat body cells of Spodoptera exigua after 10 μM CPT treatment. Additionally, we examined the effects of CPT on the growth and development of S. exigua larvae and detected the relative expression levels of selected CYP and GST genes during the CPT treatment period. Twenty-one CYP and 17 GST genes were identified from the fat body cells of S. exigua by comparative transcriptomic analyses. The relative expression of ten CYP and seven GST genes changed significantly, which suggested that these CPYs and GSTs may be involved in CPT metabolism. During exposure to CPT for 10 days, the development of S. exigua larvae was delayed and was characterized by weight inhibition and a prolonged period of development. The relative expression levels of the selected four CYP genes, CYP9A27, CYP9A186, CYP337B5, CYP321A8, and one GST gene, GSTe7, were significantly changed by CPT treatment compared to the control group. These generated data provide a basis for identifying the CPT metabolism/detoxification genes of S. exigua at the molecular level.