Identification, Expression, and Regulation of an Omega Class Glutathione S-transferase in Rhopalosiphum padi (L.) (Hemiptera: Aphididae) Under Insecticide Stress

Abstract

Glutathione S-transferases (GSTs) play an essential role in the detoxification of xenobiotic toxins in insects, including insecticides. However, few data are available for the bird cherry-oat aphid, Rhopalosiphum padi (L.). In this study, we cloned and sequenced the full-length cDNA of an omega GST gene (RpGSTO1) from R. padi, which contains 720 bp in length and encodes 239 amino acids. A phylogenetic analysis revealed that RpGSTO1 belongs to the omega class of insect GSTs. RpGSTO1 gene was highly expressed in transformed Escherichia coli and the protein was purified by affinity chromatography. The recombinant RpGSTO1 displayed reduced glutathione (GSH)-dependent conjugating activity toward the substrate 1-chloro-2, 4-dinitrobenzene (CDNB) substrate. The recombinant RpGSTO1 protein exhibited optimal activity at pH 7.0 and 30°C. In addition, a disk diffusion assay showed that E. coli overexpressing RpGSTO1 increased resistance to cumene hydroperoxide-induced oxidative stress. Real-time quantitative PCR analysis showed that the relative expression level of RpGSTO1 was different in response to different insecticides, suggesting that the enzyme could contribute to insecticide metabolism in R. padi. These findings indicate that RpGSTO1 may play a crucial role in counteracting oxidative stress and detoxifying the insecticides. The results of our study contribute to a better understanding the mechanisms of insecticide detoxification and resistance in R. padi.

De novo assembly and analysis of the transcriptome of the Dermacentor marginatus genes differentially expressed after blood-feeding and long-term starvation

“…Blood-feeding increased cellular stresses, and the majority of the GSTs were upregulated except two omega class GSTs (GSTO) that were upregulated in the M tick group (DN51816; DN50592). The GSTOs were characterized in insects, and are over-express under stress response and at the presence of insecticides [ 100 , 101 ]. Other highly expressed antioxidant proteins included catalase (DN57352; TPM: 624.90), protein disulfide isomerase (DN52494; TPM: 781.58) and glutathione peroxidase (DN40806; TPM: 1,434.27).…”

Exposure of Helicoverpa armigera Larvae to Plant Volatile Organic Compounds Induces Cytochrome P450 Monooxygenases and Enhances Larval Tolerance to the Insecticide Methomyl

“…The reaction was monitored by measuring absorbance at 340 nm for 10 min. Enzyme activity of GST was calculated as described by Balakrishnan et al [ 34 ]. The experiments were conducted with 3 biological samples and 3 technical replicates.…”

Functional diversification of three delta‐class glutathione S‐transferases involved in development and detoxification inTribolium castaneum

“…As the largest family of GSTs, cytosolic GSTs consist of at least six classes in insects: in addition to the ubiquitous sigma, theta, omega and zeta classes, two insect-specific classes of GSTs, delta and epsilon, have been identified (Friedman 2011;Shi et al 2012). As the major detoxification enzymes, interest in insect GSTs has primarily concentrated on their roles in insecticide resistance (Balakrishnan et al 2018(Balakrishnan et al , 2019. Until now, GSTs have been associated with resistance to all major classes of insecticides (Prapanthadara et al 1993).…”