Relish regulates expression of antimicrobial peptide genes in the honeybee, Apis mellifera, shown by RNA interference

Relationships of immune genes in adult honeybees (Apis mellifera) were investigated using RNA interference (RNAi). Quantitative RT-PCR was applied to estimate gene expression and the extent of gene silencing. Relish is a transcription factor and forms an important part of the IMD signalling pathway. The expression of the immune gene Relish was significantly reduced by RNAi (ca. 70%). The proposed regulation of antimicrobial peptide genes by Relish could be established for abaecin and hymenoptaecin. These two genes showed a reduction in gene expression to the same extent as Relish. However, the antimicrobial peptide gene defensin-1 was not affected which suggests defensin-1 is regulated by a different signalling pathway.