In Drosophila, the Toll receptor pathway controls the response to infection by fungi and bacteria. The Rel family of transcription factors including Dorsal, Relish, and DIF are activated by Toll and mediate the expression of antimicrobial peptides that defend Drosophila from biological invasion. Rutschmann et al. demonstrate the requirement for DIF but not Relish or Dorsal in antifungal defense. The authors generated flies that carried mutations in Dif, and found that Dif flies are susceptible to fungal infection by B. bassiana. Expression of drosomycin, an antifungal peptide, but not several other antimicrobial peptides, was reduced in Dif flies challenged with fungal infection. Subsequent genetic analyses confirmed that Dif is required for drosomycin expression. These experimental data suggest that specific Rel family members may mediate the response to particular microbial pathogens.
Rutschmann, S., Jung, A.C., Hetru, C., Reichhart, J.-M., Hoffmann, J.A., and Ferrandon, D. (2000) The Rel protein DIF mediates the antifungal but not the antibacterial host defense in Drosophila. Immunity 12: 569-580. [Online Journal]