Insight into the molecular requirements for pathogenicity of Fusarium oxysporum f. sp. lycopersici through large-scale insertional mutagenesis.
BACKGROUND
Fusarium oxysporum f. sp. lycopersici is the causal agent of vascular wilt disease in tomato. In order to gain more insight into the molecular processes in F. oxysporum necessary for pathogenesis and to uncover the genes involved, we used Agrobacterium-mediated insertional mutagenesis to generate 10,290 transformants and screened the transformants for loss or reduction of pathogenicity.


RESULTS
This led to the identification of 106 pathogenicity mutants. Southern analysis revealed that the average T-DNA insertion is 1.4 and that 66% of the mutants carry a single T-DNA. Using TAIL-PCR, chromosomal T-DNA flanking regions were isolated and 111 potential pathogenicity genes were identified.


CONCLUSIONS
Functional categorization of the potential pathogenicity genes indicates that certain cellular processes, such as amino acid and lipid metabolism, cell wall remodeling, protein translocation and protein degradation, seem to be important for full pathogenicity of F. oxysporum. Several known pathogenicity genes were identified, such as those encoding chitin synthase V, developmental regulator FlbA and phosphomannose isomerase. In addition, complementation and gene knock-out experiments confirmed that a glycosylphosphatidylinositol-anchored protein, thought to be involved in cell wall integrity, a transcriptional regulator, a protein with unknown function and peroxisome biogenesis are required for full pathogenicity of F. oxysporum.
Michielse
Caroline B
CB
Plant Pathology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands. c.b.michielse@uva.nl
van Wijk
Ringo
R
Reijnen
Linda
L
Cornelissen
Ben J C
BJ
Rep
Martijn
M
D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology; D005670:Fusarium / Q000235:genetics / Q000472:pathogenicity*; D005800:Genes, Fungal; D018551:Solanum lycopersicum / Q000382:microbiology; D016254:Mutagenesis, Insertional / Q000379:methods*; D010935:Plant Diseases / Q000382:microbiology; D014774:Virulence / Q000235:genetics
D005656:Fungal Proteins