摘要
The eicosanoid signaling pathway mediates insect immune reactions to a wide range of stimuli. This pathway begins with the biosynthesis of arachidonic acid (AA) from the hydrolysis of phospholipids catalyzed by phospholipase A_(2) (PLA_(2)). We report here that the PLA_(2) inhibitor, dexamethasone (DEX), impaired the innate immune response including nodulation, encapsulation, and melanization in Ostrinia furnacalis larvae, while AA partially reversed these effects of DEX. We cloned a full-length complementary DNA encoding a PLA_(2), designated as OfsPLA_(2), from O. furnacalis. The open reading frame of OfsPLA_(2) encodes a 195-amino acid residue protein with a 22-residue signal peptide. Sequence alignment analyses indicated that O. furnacalis PLA_(2) might be a Group III secretory PLA_(2). The highest transcript levels of OfsPLA_(2) were detected in the fat body, and its transcript levels increased dramatically after infection with Escherichia coli, Micrococcus luteus, or Beauveria bassiana. Recombinant OfsPLA_(2) significantly induced prophenoloxidase (PPO) activation in larval hemolymph in the presence of Ca^(2+) and encapsulation of agarose beads. Injection of recombinant OfsPLA_(2) into larvae resulted in increased transcript levels of attacin, defencin, and moricin-3 genes. Our results demonstrate the involvement of the eicosanoid signaling pathway in the innate immune response of O. furnacalis larvae and provide new information about the roles of O. furnacalis secretory PLA_(2) in activating PPO and antimicrobial peptide production.
基金
This work was supported by the National Nature Science Foundation of China(31672361)
the National Key R&D Program of China(2019YFE0120400).
