Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 12, 2007
Publication Date: June 22, 2007
Citation: Fravel, D.R., Moravec, B.C., Bailey, B.A. 2007. Identification and regulation of genes from a biocontrol strain of fusarium oxysporum. Phytopathology. 155:526-530.
Interpretive Summary: Fusarium wilt is a devastating disease of tomatoes caused by the soil-inhabiting fungus Fusarium oxysporum. We previously discovered a non-pathogenic F. oxysporum that reduces Fusarium wilt. The pathogen and non-pathogen strains of the fungus look exactly the same. Research is in progress to understand genetic differences between the pathogenic and beneficial F. oxysporum. This paper reports identification of genes from beneficial F. oxysporum and shows how these genes are turned on and off in response to a fungicide treatment. This information will be used by scientists developing biological control strategies for use against plant pathogens.
Differential display with three time points revealed that thiram appeared to alter expression of numerous genes in the biocontrol strain Fusarium oxysporum CS-20. Of the 101 bands purified from the differential display gel, 86 were successfully cloned, and 64 sequenced. Based on amino acid sequences, homology to known products from Gibberella zeae was found using BLAST for 25 sequences and homology to hypothetical proteins was found for 8 sequences, also from Gibberella zeae. One band (BM1 24-1) showed homology to an ABC transporter from three different fungi. Because of its association with detoxification functions, the ABC transporter was selected for further study. Mycelia of CS-20 were exposed to 25 ug a. i. thiram in liquid culture for various times from 0 to 8 hours. Quantitative real-time PCR was used to evaluate gene expression. At 30 minutes after treatment with thiram, the ABC trasporter was upregulated twenty- to twenty-five fold relative to the control treatment. The ABC transporter was upregulated 15-fold at 1 h after treatment and 10-fold at 2 h. At 8 h after treatment, there was no difference between treated and nontreated for the ABC transporter. When tested at 1 h after treatment for expression, five additional genes were also upregulated: ribonuclease III, a CCC1-like transmembrane protein, bystin, an ankyrin repeat, and a transmembrane amino acid transporter.