Plays a role in the defense of the germinating seed against microorganisms, by inhibiting the growth of a range of filamentous fungi and bacteria, especially Gram-positive bacteria. Not cytotoxic for cultured human cells and are the smallest known plant-derived antimicrobial peptides. Peptide IB-AMP4 has a higher antifungal activity than IB-AMP1. Highly expressed in dry mature seed and by the stages 2-5 of developing seed. The peptide IB-AMP1 is also detected at early stages of germination (24 hours and 48 hours postgermination). Contains repeated alternating basic mature peptide and acidic propeptide domains. The N-terminal of all peptides are blocked. The 4 cysteine residues of all peptides are involved in intrachain disulfide bonds.