Immunodetection of a brown planthopper ( N ilaparvata lugens   S tål) salivary catalase‐like protein into tissues of rice, O ryza sativa

Abstract Saliva plays an important role in host plant–phloem‐feeding insect molecular interactions. To better elucidate the role of insect saliva, a series of experiments were conducted to establish if catalase from the salivary glands of the brown planthopper ( BPH ; N ilaparvata lugens S tål) was secreted into rice host plant tissue during feeding. Catalase is the main enzyme that decomposes hydrogen peroxide ( H 2 O 2 ) at high concentrations. H 2 O 2 is a part of the free radicals system that mediates important physiological roles including signalling and defence. Previous studies have suggested that H 2 O 2 is involved in the rice endogenous response to BPH feeding. If, the BPH secretes catalase into host plant tissue this will counter the effects of H 2 O 2 , from detoxification to interfering with plant signalling and defence mechanisms. When BPHs were fed on a hopper‐resistant rice variety for 24 h, catalase activity in the salivary glands increased 3.5‐fold compared with hoppers fed on a susceptible rice variety. Further supporting evidence of the effects of BPH catalase was demonstrated by immunodetection analyses where results from two independent sources: BPH ‐infested rice tissue and BPH‐probed artificial diets, suggest that the BPH secretes catalase‐like protein during feeding. The possible physiological roles of BPH ‐secreted catalase are discussed.