immunity: the gene encodes two host defence peptides with pathogen-specific roles.

Antimicrobial peptides (AMPs) are key to defence against infection in plants and animals. Use of AMP mutations in has now revealed that AMPs can additively or synergistically contribute to defence . However, these studies also revealed high specificity, wherein just one AMP contributes an outsized role in combatting a specific pathogen. Here, we show the locus () is more complex than previously described. In addition to its namesake peptide 'Drosocin', it encodes a second mature peptide from a precursor via furin cleavage. This peptide corresponds to the previously uncharacterized 'Immune-induced Molecule 7'. A polymorphism (Thr52Ala) in the Drosocin precursor protein previously masked the identification of this peptide, which we name 'Buletin'. Using mutations differently affecting Drosocin and Buletin, we show that only Drosocin contributes to gene-mediated defence against . Strikingly, we observed that Buletin, but not Drosocin, contributes to the gene-mediated defence against , including an importance of the Thr52Ala polymorphism for survival. Our study reveals that the gene encodes two prominent host defence peptides with different specificity against distinct pathogens. This finding emphasizes the complexity of the humoral response and demonstrates how natural polymorphisms can affect host susceptibility.