Antimicrobial proteins from cowpea root exudates: inhibitory activity against Fusarium oxysporum and purification of a chitinase-like protein

• Published in: Plant and soil 2005-05, Vol.272 (1-2), p.223-232
• Main Authors: Nobrega, F.M, Santos, I.S, Cunha, M. da, Carvalho, A.O, Gomes, V.M
• Format: Article
• Language: English
• Subjects: Acetates; antifungal properties; antifungal proteins; beta-glucanase; Biological and medical sciences; chitinase; cowpeas; Enzymes; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; Fungi; Fusarium; Fusarium oxysporum; hydroponics; lipid transfer protein; mycelium; nutrient solutions; Pathogens; Pathology, epidemiology, host-fungus relationships. Damages, economic importance; Phosphates; Phytopathology. Animal pests. Plant and forest protection; plant pathogenic fungi; plant proteins; Plant roots; Plants; polyacrylamide gel electrophoresis; Root exudates; seedlings; Seeds; tissue distribution; tropical and subtropical crops; Vigna unguiculata
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-004-4954-1

Plants exude a variety of substances through their external surfaces and from germinating seeds, some of which have an inhibitory action against plant pathogens. The aim of this study was the investigation and characterization of defense proteins present in exudates from roots of cowpea seedlings (Vigna unguiculata (L.) Walp.). Root exudates were collected from seedlings that were grown hydroponically in three different media, including, 100 mM sodium acetate buffer pH 4.5, water pH 6.0 and 100 mM sodium phosphate buffer pH 7.5. The proteins from these exudates were analyzed by SDS-PAGE and SDS-Tricine-PAGE and the presence of antimicrobial proteins in the exudates was investigated by immunological and enzymatic assays. Results showed that roots from cowpea seedlings contained β-1,3-Glucanases, chitinases and lipid transfer proteins (LTPs), all of which may potentially function as plant defense proteins. Immunolocalization of one of these proteins, chitinase, revealed its presence in the xylem cell wall vessel elements. These exudates also demonstrated an inhibitory effect on the growth of the fungus, Fusarium oxysporum, in vitro. The results suggest that plant roots may exude a variety of proteins that may function to repress the growth of root pathogenic fungi.