Use of a host-pathogen interaction system to test whether oxalic acid is the sole pathogenic determinant in the exudate of Sclerotinia trifoliorum

A host-pathogen interaction system was used to test the hypothesis that oxalic acid is the sole pathogenic determinant in the exudate of Sclerotinia trifoliorum. The system allowed exposure of germinating alfalfa seedlings (Medicago sativa) to continuously produced fungal exudate without physical co...

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Bibliographic Details
Published in:Phytopathology 1991-12, Vol.81 (12), p.1546-1550
Main Authors: Callahan, F.E. (USDA, ARS, Crop Science Research Laboratory, Mississippi State), Rowe, D.E
Format: Article
Language:English
Subjects:
ACIDE OXALIQUE
ACIDO OXALICO
Agronomy. Soil science and plant productions
Biological and medical sciences
DOSAGE BIOLOGIQUE
ELECTROFORESIS
ELECTROPHORESE
ENSAYO BIOLOGICO
EXSUDAT
EXUDADOS
Fundamental and applied biological sciences. Psychology
Fungal plant pathogens
MEDICAGO SATIVA
Pathology, epidemiology, host-fungus relationships. Damages, economic importance
Phytopathology. Animal pests. Plant and forest protection
PODER PATOGENO
POUVOIR PATHOGENE
RELACIONES HUESPED PARASITO
RELATION HOTE PARASITE
SCLEROTINIA TRIFOLIORUM
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Summary:A host-pathogen interaction system was used to test the hypothesis that oxalic acid is the sole pathogenic determinant in the exudate of Sclerotinia trifoliorum. The system allowed exposure of germinating alfalfa seedlings (Medicago sativa) to continuously produced fungal exudate without physical contact with the fungus. Blockage of diffusion of macromolecular components ( 3,500 mol wt) of the exudate without alteration of oxalic acid levels reduced the observed inhibition of alfalfa radicle length by 40-50%. Such results indicate that in this system oxalic acid is not the sole inhibitory factor and that other, yet unidentified, macromolecular components share a codeterminant role in the observed inhibitory effect. The techniques described should be generally applicable to characterization of exudates of other pathogenic fungi or bacteria that are cultured on solid media, while allowing flexibility in design of pertinent bioassays
ISSN:0031-949X
1943-7684
DOI:10.1094/Phyto-81-1546