STRUCTURAL AND ANTIFUNGAL PROPERTIES OF A PATHOGENESIS-RELATED PROTEIN FROM WHEAT KERNEL

We have purified and characterized a protein from the water-soluble fr action of wheat kernel (Triticum aestivum cv. S. Pastore) consisting o f a single polypeptide chain blocked at its N-terminus by a pyroglutam ate residue; the complete amino acid sequence has been determined by a utomated sequence analysis performed on peptide fragments obtained by enzymatic hydrolyses of the protein. Homology studies have shown that this protein is very similar (97% sequence identity) to the previously characterized wheatwin1 as well as to other members of the pathogenes is-related (PR) proteins of class 4; in analogy with wheatwin1, we hav e termed this protein wheatwin2. Both wheatwin1 and wheatwin2 have spe cific antifungal activity toward the wide-host-range pathogen Botrytis cinerea and the wheat-specific pathogenic fungi of wheat Fusarium cul morum and Fusarium graminearum of groups 1 and 2. On the basis of thei r structural and functional properties, wheatwin1 and wheatwin2 can be classified as members of the PR4 protein family; this represents the first report concerning the presence of this kind of protein in wheat.