Partners and International Organizations
(English)
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A, B, CY, CZ, DK, FIN, F, D, H, IRL, I, NL, N, P, RO, SK, E, S, CH, GB
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Abstract
(English)
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Certain phytopathogenic fungi secrete oxalic acid as pathogenicity factor. Some examples are the necrotrophic fungi Sclerotinia sclerotiorium and Botrytis cinerea. Several functions of oxalic acid in pathogen-host interaction have been proposed: (i) the secretion of oxalic acid lowers the pH on the plant surface that favours the action of pectolytic enzymes of the pathogen, (ii) oxalic acid blocks defence signal pathways in the plant, (iii) oxalic acid chelates bivalent ions in the middle lamella of cell walls, hence actively destroying the plant tissue. Consequently, by degrading oxalic acid at the onset of host pathogen interaction, it should be possible to impede the infection process. The aim of the present project is to evaluate the possibility to use oxalate-degrading bacteria that colonize the plant surfaces and protect the plant from pathogen attack. In a first step, oxalate-degrading bacteria were isolated from the environment by enrichment in the rhizosphere of plants infected with S. sclerotiorum. Out of the 42 isolates that degrade oxalate when grown on agar plates, 4 strains were selected. They show a medium to strong protective activity on Arabidopsis thaliana leaves against S. sclerotiorum. These Ox-strains, together with the biocontrol reference strain CHA0r, were used for protection assays in different pathosystems. Interesting results have been obtained against the oxalate-producing fungus B. cinerea. We have identified 4 strains that protect tomato, cucumber and Arabidopsis against this pathogen.
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