Submitted to: New Phytologist
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/15/2002
Publication Date: N/A
Citation: Interpretive Summary: Fusarium oxysporum is a fungus that lives in the soil. Most of the F. oxysporum in soil lives on dead organic matter (saprophytic strains). Some of the F. oxysporum in soil can cause disease (pathogenic strains), especially wilt disease in plants. Other F. oxysporum (biocontrol strains) can prevent disease caused by pathogenic strains. Saprophytic, pathogenic and biocontrol strains all look the same. The only way to tell them apart is to see how they behave. The only chemicals that can reduce losses due to Fusarium wilt disease are soil fumigants. These fumigants damage the environment. Thus, research is being conducted to see if biocontrol strains can be used to control Fusarium wilt. Most of the biocontrol strains work by competing against the pathogenic ones for nutrients or by occupying infection sites on roots. Some biocontrol strains work by triggering the plants' own defense mechanisms. This article presents an overview of this research. This information will be used by scientists developing alternative control measures for Fusarium wilt.
Technical Abstract: This article presents an overview of the soil-inhabiting fungus Fusarium oxysporum, with emphasis on the use of nonpathogenic F. oxysporum to control wilt diseases cased by the pathogenic strains. The pathogen is very host specific and usually each strain of the pathogen will attack only one kind of plant or even just certain cultivars of that plant. This disease is currently controlled chemical fumigation of soil prior to planting or, when available, by resistant cultivars. Environmental concerns about chemical fumigants, particularly methyl bromide, have stimulated interest in alternative control measures. The most effective and consistent biocontrol strains available are strains of F. oxysporum that look exactly like the pathogenic ones. Biocontrol by competition and induced resistance has been documented, and parasitism antibiosis have not been observed. Competition for nutrients and infection sites on roots is the most common mechanism. Competition has been studied using biocontrol strains modified to express the Gus gene. These studies confirmed that a biocontrol strain penetrated roots, but not the vascular system of the plant. This information will be used by scientists developing alternative control measures for Fusarium wilt.