Effect of RNAi Targeting SeGrx1 on the Cytotoxicity and Insecticide Susceptibility of Camptothecin in Spodoptera exigua

Abstract

Glutaredoxins (Grxs) are a class of small, heat-stable, acidic proteins which have been implied in various biological activities in cells, including the defense against oxidative stress induced by various biotic and abiotic factors. In this paper, the effects of RNAi targeting SeGrx1 on the cytotoxicity and insecticide susceptibility of camptothecin (CPT) in Spodoptera exigua were investigated. Results showed that the cytotoxicity of CPT to the cells of S. exigua is heightened significantly by the silencing of SeGrx1. In the larvae of S. exigua, the mortality was significantly increased compared to CPT-alone treatment group at 120 h after knocking down the SeGrx1 gene. Taken together, our results confirmed that SeGrx1 in S. exigua played an important role in protecting the cells from the cytotoxicity induced by CPT, and the sensitivity of S. exigua larvae to CPT was increased by the silencing of SeGrx1. Our findings might provide basic information for understanding the function of Grxs and a strategy in insect pest control of RNAi technology combined with pesticides.

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

“…In agriculture, much interest has been focused on developing CPTs as potential biological pesticides to control agricultural pests due to the unique action mechanisms and insecticidal activities of CPTs. It has been documented that CPTs are effective against several pest insects, including Spodoptera exigua [6,7], S. litura [8], S. frugiperda [9], Nilaparvata lugens, Brevicoryne brassicae, and Chilo suppressalis [10]. In our previous studies, CPTs induced cytotoxicity against IOZCAS-Spex-II cells derived from S. exigua by promoting apoptosis [11] and increasing intracellular oxidative stress [12,13].…”

Chitinase is a Potent Insecticidal Molecular Target of Camptothecin and Its Derivatives

“…19 The insecticidal activity of CPT against S. exigua increased when glutaredoxin 1 was silenced by RNA interference. 20 Most recently, CPT was also observed to affect the ultrastructure of the midgut and fat body in lepidopteran insects, and various genes with different functions were upregulated by treatment with CPT, including those encoding group II insect chitinase (chitinase 10) and group h chitinase (chitinase A). 21−23 This result caught our attention because we previously reported 10-hydroxycamptothecin (10-HCPT) to be an inhibitor of chitinolytic enzymes from the Asian corn borer Ostrinia furnacalis.…”