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Title: Characterization of Two ABC Transporters from Biocontrol and Phytopathogenic Fusarium oxysporus

Author
item Fravel, Deborah
item Moravec, Brian
item Jones, Richard
item Costanzo, Stefano

Submitted to: Physiological and Molecular Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/18/2008
Publication Date: 1/1/2008
Citation: Fravel, D.R., Moravec, B.C., Jones, R.W., Costanzo, S. 2008. Characterization of two ABC transporters from biocontrol and phytopathogenic fusarium oxysporus. Physiological and Molecular Plant Pathology. 73:2-8.

Interpretive Summary: This work was conducted to identify genetic differences (markers) to rapidly distinguish among the groups of the soil-inhabiting fungus Fusarium oxysporum. Genetic sequences for two genes that help to remove toxic compounds from cells were compared among 19 plant beneficial (biocontrol) and plant pathogenic strains. While the genetic sequences were very similar for all fungi tested, the part of the genetic sequence that controls when the gene turns on or off (promoter region) was different between the biocontrol fungi and the pathogens. An additional study showed that one of these genes in particular was turned on and off differently by biocontrol and pathogenic strains when they were exposed to a toxin. This information is useful to scientists developing methods for rapid detection of F. oxysporum and rapidly determining whether or not it is pathogenic, to scientists developing methods to predict whether or not wilt disease might develop in a field, and to scientists searching for and improving biocontrol methods.

Technical Abstract: ABC transporter genes from four strains of Fusarium oxysporum [two biocontrol and two phytopathogenic (f. sp. lycopersici Race 1) isolates] indicated that this gene is well conserved. However, sequences of promoter regions of FoABC1 differed between 8 phytopathogenic and 11 biocontrol strains of F. oxysporum. A phylogenetic tree of promoter sequences indicated that pathogenic strains were in one clade and biocontrol agents in three others. Although sequencing of promoter regions was done on a relatively small number of strains, results suggest that FoABC1 may be regulated differently between phytopathogenic and biocontrol strains of the fungus. In studies on the activity (RNA) of FoABC1 in the presence of the fungicide thiram, one pathogen was up regulated by a brief expose to thiram, the other pathogenic strain was down regulated to undetectable levels, while the two biocontrol strains were not significantly changes. After a 1 h exposure to thiram, the level of expression of one pathogen remained undetectable, while the other pathogen and both biocontrol agents showed similar levels of expression all slightly up regulated compared to the time zero control. Additional research is needed to further understand the significance of the genetic difference in promoter regions between phytopathogenic and biocontrol strains for FoABC1.