Functional Analysis of an Omega-GST Gene 2 in Tribolium castaneum.

The omega glutathione S-transferases (GSTOs) are a class of cytosolic GSTs and play important roles in antioxidant defense in insects. However, the functions of some GSTOs remain unclear. Here, we performed functional analysis of a GSTO2 in Tribolium castaneum (TcGSTO2). Sequence alignment indicated that this gene was conserved among insects. During development, TcGSTO2 was highly expressed in the late stage of larva and pupa and the hemolymph, fat body, malpighian tubules of late larva. After treatment with various insecticides such as DDV, KBV, phoxim, and lambda-cyhalothrin, the expression level of TcGSTO2 was significantly increased, and knockdown of TcGSTO2 reduced the resistance to the insecticides. Exposure to various types of oxidative stress, including heat, cold, UV, and pathogenic microbes, largely induced TcGSTO2 expression, and overexpression of TcGSTO2 in E. coli increased the resistance to oxidative stress induced by paraquat and cumene hydroperoxide. Our study showed that TcGSTO2 participated in the cellular detoxification and antioxidant defense, deepening our understanding of the functional diversity of GSTOs in insects.