CpGSTd3 is a lambda-Cyhalothrin Metabolizing Glutathione S-Transferase from Cydia pomonella (L.)

Abstract

Little is known about the role of specific delta GST genes in the detoxification of lambda-cyhalothrin in the global quarantine fruit pest codling moth, Cydia pomonella (L.). Real-time quantitative PCR shows that CpGSTd3 was ubiquitously expressed at all developmental stages and is most abundant in the larval stage and lowest in the egg stage; the mRNA level of CpGSTd3 is higher in the midgut and Malpighian tubules of fourth-instar larvae and abdomens of adults than in other tissues. Exposure of fourth-instar larvae to an LD10 dosage of lambda-cyhalothrin significantly induced the transcript of CpGSTd3 at 3 h, but the mRNA level was down-regulated after 12 h of treatment. Recombinant CpGSTd3 expressed in Escherichia coli was able to catalyze the conjugation of 1-chloro-2,4-dinitrobenzene (CDNB) and with an IC50 value of 0.65 mM for lambda-cyhalothrin. Metabolism assays indicate that recombinant CpGSTd3 could metabolize lambda-cyhalothrin. These results suggest that CpGSTd3 is probably a lambda-cyhalothrin metabolizing GST in C. pomonella.

Functional characterization of a novel λ‐cyhalothrin metabolizing glutathione S‐transferase, CpGSTe3, from the codling moth Cydia pomonella

“…This strain had been raised in the laboratory for more than 50 generations without exposure to any insecticides. A detailed description of insect rearing is given in Wang et al …”

“…The codling moth, Cydia pomonella (Lepidoptera: Tortricidae), is a major pest of pome fruits worldwide and is also a pest of quarantine concern for pome fruits exports to China . In orchards, the larvae bore into the center of fruits to feed on the sarcocarp and seeds, causing great harm to fruit production throughout the world .…”

“…At present, control of this pest mainly relies on chemical insecticides . However, frequent application of insecticides not only causes potential risks to both the environment and fruit safety, but also generates insecticide resistance . The λ‐cyhalothrin is one of the recommended and most commonly used insecticides for C. pomonella control worldwide.…”

“…They catalyze the conjugation of reduced glutathione (GSH) to electrophilic substrates including insecticides, increasing the substrate's water solubility and then promoting the excretion of insecticides from the cell . In insects, only cytosolic and microsomal GSTs have been found, and these cytosolic GSTs have been divided into six subclasses: delta, epsilon, sigma, omega, zeta, and theta . Among these subclasses, delta and epsilon GSTs are unique to insects, and have been associated with insecticide metabolism and resistance .…”

“…However, the role of GSTs participating in the detoxification of insecticides primarily reported in delta and epsilon paralogous isoforms, therefore substantial experimental effort in the functional characterization GSTs in insecticide detoxification has been focused on delta and epsilon GSTs in insects . In our previous study, a total of four delta GST genes were identified from C. pomonella by searching a transcriptome database . Recombinant CpGSTd1 and CpGSTd3 enzymes have been shown to be indirectly involved in the metabolism of λ‐cyhalothrin .…”