His-Ala-Phe-Lys Peptide from Possesses Antifungal Activity

, which belongs to the complex, has been shown to possess antifungal activity against several plant fungal pathogens; however, the antifungal compounds are yet to be identified. Here, we identified the antifungal compounds produced by using genetic and metabolomic approaches. We generated a Tn5 transposon mutation library of 3,000 mutants and isolated three mutants with reduced antifungal activity against the plant fungal pathogen . Among the mutants, the M464 mutant exhibited the weakest antifungal activity. In the M464 genome, the transposon was inserted into the gene, encoding uroporphyrin-III methyltransferase. Deletion of the gene also resulted in reduced antifungal activity, indicating that the gene contributed to the antifungal activity of . Furthermore, a comparison of the differential metabolites between wild type and the ∆ mutant showed a significantly decreased level of tetrapeptide His-Ala-Phe-Lys (Hafk) in the ∆ mutant. Therefore, a Hafk peptide with D-amino acid residues was synthesized and its antifungal activity was evaluated. Notably, the Hafk peptide displayed significant antifungal activity against and , two plant pathogens that cause destructive fungal diseases. Overall, a novel antifungal compound (Hafk) that can be used for the biocontrol of fungal diseases in plants was identified in .