Biological control of soilborne plant pathogens represents a promising alternative to synthetic fungicides, with a number of bioformulates already available for practical use. However, the efficacy of biocontrol agents needs to be optimized to improve the reliability of biocontrol products and make them truly competitive with chemicals. The aim of this work is to gain a deeper understanding on the biochemical and molecular mechanisms underlying bacterial antagonism of soilborne fungi. Selected isolates of the genera Bacillus and Pseudomonas obtained from suppressive soil were tested against a collection of genetically characterized mutants of the tomato vascular wilt pathogen Fusarium oxysporum f. sp. lycopersici (Fol). Bacterial culture filtrates were fractionated according to molecular weight and tested for in vitro activity on mycelial growth and germ-tube elongation of the Fol wild type strain and different gene knockout mutants. Scanning electron microscopy was performed both in vitro and on tomato roots, to study the in vivo interaction among the bacterial cells of the most effective antagonists and the hyphae of the Fol wild type strain and selected fungal mutants. The results of this study will be discussed in relation to the possible modes of action involved in the tritrophic interaction between biocontrol bacteria, pathogen and host plant.

Exploring the interaction between bacterial biocontrol agents and genetically characterized mutants of Fusarium oxysporum

LIMA, Giuseppe
2008

Abstract

Biological control of soilborne plant pathogens represents a promising alternative to synthetic fungicides, with a number of bioformulates already available for practical use. However, the efficacy of biocontrol agents needs to be optimized to improve the reliability of biocontrol products and make them truly competitive with chemicals. The aim of this work is to gain a deeper understanding on the biochemical and molecular mechanisms underlying bacterial antagonism of soilborne fungi. Selected isolates of the genera Bacillus and Pseudomonas obtained from suppressive soil were tested against a collection of genetically characterized mutants of the tomato vascular wilt pathogen Fusarium oxysporum f. sp. lycopersici (Fol). Bacterial culture filtrates were fractionated according to molecular weight and tested for in vitro activity on mycelial growth and germ-tube elongation of the Fol wild type strain and different gene knockout mutants. Scanning electron microscopy was performed both in vitro and on tomato roots, to study the in vivo interaction among the bacterial cells of the most effective antagonists and the hyphae of the Fol wild type strain and selected fungal mutants. The results of this study will be discussed in relation to the possible modes of action involved in the tritrophic interaction between biocontrol bacteria, pathogen and host plant.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11695/8586
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