The present invention relates to an antifungal protein, AlfAFP1, which is a modified form of an antifungal protein isolated from Medicago plants, the modified form exhibiting enhanced anti-fungal activity for controlling fungal pathogenesis in plants. A method for inhibiting fungal colonization of plants is described which includes preparation of nucleotide sequences encoding the modified antifungal protein, preparation of vectors containing the nucleotide coding sequence, and methods for transforming plants with the nucleotide sequences. The polypeptide can be formulated into compositions useful in controlling plant pathogenic fungi.