The JAK/STAT Signaling Pathway Mediates Antibacterial Immunity in the Soybean Aphid Aphis glycines

The JAK/STAT pathway is a conserved signaling pathway involved in insect immune regulation. Although its antibacterial role has been investigated in some aphids, evidence is lacking for Aphis glycines. In this study, we identified JAK/STAT pathway-related genes in A. glycines and examined their roles in antibacterial defense. Candidate genes were identified and characterized through sequence, domain, and phylogenetic analyses. Developmental expression and transcriptional responses to bacterial infection were determined by qRT-PCR, and gene function was evaluated by RNA interference followed by bacterial challenge. Six putative JAK/STAT pathway-related genes were identified, including AglyJak, AglyDome-1, AglyDome-2, AglyDome-3, AglyStat92E-1, and AglyStat92E-2. Conserved domain architecture and phylogenetic analysis confirmed these genes as A. glycines JAK/STAT orthologs. Expression profiling showed that, except for AglyJak and AglyDome-2, most genes were most highly expressed in early nymphal stages, particularly in first-instar nymphs. After injection with Escherichia coli or Staphylococcus aureus, the transcript levels of AglyJak, AglyDome, and AglyStat genes increased significantly. Gene silencing significantly reduced aphid survival following bacterial infection. These results indicate that JAK/STAT pathway-related genes participate in the antibacterial defense of A. glycines and provide candidate targets for further studies on immune regulation and biologically based management of this pest.