The gene coding for a new transcription factor (ftf1) of Fusarium oxysporum is only expressed during infection of common bean q Brisa Ramos a , Fernando M. Alves-Santos b , M. Asuncio ´n Garcı ´a-Sa ´nchez a , Noemı ´ Martı ´n-Rodrigues a , Arturo P. Eslava a , Jose ´ Marı ´a Dı ´az-Mı ´nguez a, * a Centro Hispano-Luso de Investigaciones Agrarias (CIALE), Departamento de Microbiologı ´a y Gene ´tica, Universidad de Salamanca, Avda, Campo Charro s/n, 37007 Salamanca, Spain b Departamento de Produccio ´ n Vegetal y Recursos Forestales, ETSIIAA de Palencia, Universidad de Valladolid, Avda, Madrid 57, 34071 Palencia, Spain Received 18 October 2006; accepted 6 March 2007 Available online 16 March 2007 Abstract We report the isolation and analysis of the gene encoding ftf1 (Fusarium transcription factor 1), a previously undescribed putative transcription factor from highly virulent strains of Fusarium oxysporum f.sp. phaseoli that is transcribed specifically during early stages of infection of its host common bean (Phaseolus vulgaris L.). The predicted 1080 amino acid ftf1 protein contains a Zn(II)2-Cys6 binu- clear cluster DNA-binding motif. ftf1 expression during axenic growth in culture was not detected by either Northern or RT-PCR. On the contrary, in planta transcription of ftf1 is increased about 24 h after plant inoculation, as detected by real-time RT-PCR. This result suggests that ftf1 has a role in the establishment of the fungus within the plant and/or the progress of the disease. Multiple copies of ftf1 are present in highly virulent strains of F. oxysporum f.sp. phaseoli. Ó 2007 Elsevier Inc. All rights reserved. Keywords: Pathogenicity; Transcription factor; Fusarium oxysporum; Fusarium wilt; Virulence; Binuclear Zn cluster 1. Introduction Fusarium oxysporum Schlechtend.:Fr. f.sp. phaseoli J.B. Kendrick and W.C. Snyder is the causal agent of Fusarium wilt of common bean (Phaseolus vulgaris L.), one of the most serious diseases of this crop worldwide. Seven races of the pathogen have been described based on host differentials (Alves-Santos et al., 2002a; Woo et al., 1996). The correlation of races with geographic origin (Alves-Santos et al., 2002a) and the differences found among the pathogenic strains in vegetative com- patibility groups (VCGs), intergenic spacer (IGS) region of the nuclear ribosomal DNA and electrophoretic karyotype patterns (Alves-Santos et al., 1999) indicate a high level of diversity and suggest a polyphyletic origin for the pathogenic isolates of this forma specialis. In terms of pathogenicity highly virulent strains are able to kill common bean plants in about two weeks, while weakly virulent strains take a longer time to do so (Alves-Santos et al., 2002a). In a previous study (Alves-Santos et al., 2002b) we isolated a sequence characterized amplified region (SCAR) marker, named SCAR-B310A280, that enables the in planta detection of highly virulent F. oxysporum f.sp. phaseoli strains as early as 5 h post-infection. This SCAR marker contains an ORF with a Zn(II)2-Cys6 binuclear cluster DNA-binding domain. This domain was first characterized in the Saccharomyces cerevisiae GAL4 protein (Pan and Coleman, 1990) and is appar- ently unique to fungi. Most proteins with this motif are transcriptional activators involved in a variety of metabolic pathways (Todd et al., 1997). Some of these 1087-1845/$ - see front matter Ó 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.fgb.2007.03.003 q Nucleotide sequence accession number: Nucleotide sequence data for the Fusarium oxysporum f.sp. phaseoli ftf1 gene is available in the GenBank database under Accession No. DQ280313. * Corresponding author. Fax: +34 923 294663. E-mail address: josediaz@usal.es (J.M. Dı ´az-Mı ´nguez). www.elsevier.com/locate/yfgbi Fungal Genetics and Biology 44 (2007) 864–876