Antioxidant Enzymes and Heat Shock Protein Genes from Are Involved in Stress Defense upon Heat Shock.

Psocids are a new risk for global food security and safety because they are significant worldwide pests of stored products. Among these psocids, has developed high levels of resistance or tolerance to heat treatment in grain storage systems, and thus has led to investigation of molecular mechanisms underlying heat tolerance in this pest. In this study, the time-related effects of thermal stress treatments at relatively high temperatures on the activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), peroxidases (POD), glutathione-S-transferases (GST) and malondialdehyde (MDA), of were determined. Thermal stress resulted that had a significantly higher MDA concentration at 42.5 °C, which indicated that the heat stress increased lipid peroxidation (LPO) contents and oxidative stress in this psocid pest. Heat stress also resulted in significant elevation of SOD, CAT and GST activities but decreased POD activity. Our data indicates that different antioxidant enzymes contribute to defense mechanisms, counteracting oxidative damage in varying levels. POD play minor roles in scavenging deleterious LPO, while enhanced SOD, CAT and GST activities in response to thermal stress likely play a more important role against oxidative damage. Here, we firstly identified five (four and one ) from psocids, and most of these (except ) are highly expressed at fourth instar nymph and adults, and likely presents as a cognate form of HSP due to its non-significant changes of expression. Most (except ) are significantly induced at moderate high temperatures (<40 °C) and decreased at extreme high temperatures (40-45 °C), but can be significantly induced at all high temperatures. Results of this study suggest that the and genes are involved in tolerance to thermal stress in , and antioxidant enzymes and heat shock proteins may be coordinately involved in the tolerance to thermal stress in psocids.