The FTF gene family regulates virulence and expression of SIX effectors in Fusarium oxysporum

• DOI: 10.1111/mpp.12373
• Publication Date: 2016-01-28T09:03:17Z
• Authors: Jonathan Niño‐Sán...; Virginia Casado‐D...; Vega Tello; José J. De Vega‐B...; Brisa Ramos; Serenella A. Sukno; José María Díaz M...
• Keywords: Virulence Factors; Genes, Fungal; Green Fluorescent Proteins; Gene Dosage; Fungal Proteins; 03 medical and health sciences; Transformation, Genetic; Fusarium; Solanum lycopersicum; Gene Expression Regulation, Fungal; Sequence Homology, Nucleic Acid; Pathogenicity; Fusarium wilt; Phylogeny; Plant Diseases; 2. Zero hunger; 0303 health sciences; Virulence; 2409 Genética; Fabaceae; Original Articles; FTF; Blotting, Southern; Multigene Family; Host-Pathogen Interactions; Mutation; Effector; RNA Interference; Transcription factor; 2414 Microbiología; Genomic expansion

SummaryThe FTF (Fusarium transcription factor) gene family comprises a single copy gene, FTF2, which is present in all the filamentous ascomycetes analysed, and several copies of a close relative, FTF1, which is exclusive to Fusarium oxysporum. An RNA‐mediated gene silencing system was developed to target mRNA produced by all the FTF genes, and tested in two formae speciales: F. oxysporum f. sp. phaseoli (whose host is common bean) and F. oxysporum f. sp. lycopersici (whose host is tomato). Quantification of the mRNA levels showed knockdown of FTF1 and FTF2 in randomly isolated transformants of both formae speciales. The attenuation of FTF expression resulted in a marked reduction in virulence, a reduced expression of several SIX (Secreted In Xylem) genes, the best studied family of effectors in F. oxysporum, and lower levels of SGE1 (Six Gene Expression 1) mRNA, the presumptive regulator of SIX expression. Moreover, the knockdown mutants showed a pattern of colonization of the host plant similar to that displayed by strains devoid of FTF1 copies (weakly virulent strains). Gene knockout of FTF2 also resulted in a reduction in virulence, but to a lesser extent. These results demonstrate the role of the FTF gene expansion, mostly the FTF1 paralogues, as a regulator of virulence in F. oxysporum and suggest that the control of effector expression is the mechanism involved.