Abstract: 【Aim】 The aim of this study is to reveal the function of peroxiredoxin 2 (ApPrx2) in the pea aphid, Acyrthosiphon pisum during bacterial infection. 【Methods】 The open reading frame of ApPrx2 was cloned and heterologously expressed in Escherichia coli. The antioxidative function of the purified recombinant ApPrx2 was characterized. The H₂O₂ concentration and ApPrx2 transcription level were detected in pea aphids after bacterial infections of Pseudomonas aeruginosa and Staphylococcus aureus. RNA interference was used to knockdown the expression of ApPrx2. H₂O₂ concentration, bacterial load and the survival rate of aphids were evaluated after the knockdown of ApPrx2. 【Results】 Sequence alignment showed that ApPrx2 is highly similar to 2-Cys Prxs from other insect species. In vitro assays demonstrated that the recombinant ApPrx2 protein degraded H₂O₂, and ApPrx2 expression rendered E. coli cells resistant to H₂O₂. Infections of the bacteria P. aeruginosa and S. aureus increased the H₂O₂ concentration and ApPrx2 expression in the pea aphids. The knockdown of ApPrx2 expression increased the H₂O₂ concentration, reduced the bacteria load and increased the mortality rate of aphids infected with S. aureus. 【Conclusion】 ApPrx2 functions as an antioxidative protein protecting pea aphids from stress induced by infection with bacteria, particularly S. aureus.

Key words: Acyrthosiphon pisum, peroxiredoxin, reactive oxygen species (ROS), antioxidative response, bacterial infection