New Virulence Groups in Fusarium oxysporum f. sp. phaseoli: The Expression of the Gene Coding for the Transcription Factor ftfl Correlates with Virulence

• Published in: Phytopathology 2011-04, Vol.101 (4), p.470-479
• Main Authors: DE VEGA-BARTOL, Jose J, MARTIN-DOMINGUEZ, Raúl, RAMOS, Brisa, GARCIA-SANCHEZ, María-Asunción, DIAZ-MINGUEZ, Jose Maria
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; Fusarium oxysporum; Phaseolus vulgaris; Phytopathology. Animal pests. Plant and forest protection
• ISSN: 0031-949X; 1943-7684
• DOI: 10.1094/PHYTO-09-10-0252

Fusarium oxysporum f. sp. phaseoli strains isolated from runner bean plants showing Fusarium wilt symptoms were characterized. The analysis of the genetic diversity of these strains and the comparison with strains formerly isolated from diseased common bean plants grown in the same region of Spain indicated a close genetic similarity among them. Pathogenicity assays carried out on runner bean plants showed virulence differences that allowed the classification of these strains into three groups: super virulent, highly virulent, and weakly virulent. However, all the analyzed strains behaved as highly virulent when inoculated on common bean plants, indicating that virulence is specific of the host-pathogen interaction. We also analyzed the number of copies and expression of the gene encoding the transcription factor ftfl, which has been shown to be specific of virulent F. oxysporum strains and highly up-regulated during plant infection. In planta real-time quantitative polymerase chain reaction expression analysis showed that expression of ftfl was correlated with the degree of virulence. The comparative analysis of the polymorphic copies of ftfl detected in the strains here characterized and those detected in the genome sequence of F. oxysporum f. sp. lycopersici strain 4287 indicates that some of the copies are likely nonfunctional.