Plant defense peptide with antifungal activity against F.oxysporum and B.cinerea. Stable under extremes of pH. Stable under extremes of temperature. Petals. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. When compared to other plant defensins, the petunia defensins have an additional fifth disulfide bond. Belongs to the DEFL family.