Fusarium sp growth inhibition by wheat germ agglutinin

The antifungal role of wheat germ agglutinin (WGA) isolated from a Romanian dihaploid variety of wheat against two pathogenic fungal species of Fusari um, F. graminearum and F. oxysporum, is demonstrated. WGA was prepared from unprocessed wheat germs by a new purification procedure using chitin and f etuin-Sepharose as affinity chromatography supports. SDS-PAGE and chitinase assay showed that the WGA preparation migrated as a single protein band an d was devoid of any contaminating enzyme chitinase, well known for its anti fungal effects. Based on its affinity for N-acetylglucosamine residues, WGA binding to the chitin-containing walls of the fungi was detected by fluore scence microscopy using WGA coupled with fluorescein isothiocyanate (FITC). In vitro testing of WGA action on early developmental stages of both funga l strains resulted in various modifications of the germ tubes, visualised b y light microscopy: swelling, vacuolation of the cellular content and lysis of cell walls. Viability tests performed on potato tuber slices showed tha t the microbial infection was prevented from spreading by pretreatment of t he fungal suspension with WGA. (C) 1999 Elsevier Science B.V. All rights re served.