title: Combined action of the major secreted exo- and endopolygalacturonases is required for full virulence of Fusarium oxysporum.
abstract: The genome of the tomato pathogen Fusarium oxysporum f. sp. lycopersici encodes eight different polygalacturonases (PGs): four endoPGs and four exoPGs. Quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) revealed that endoPGs pg1 and pg5 and exoPGs pgx4 and pgx6 are expressed at significant levels during growth on citrus pectin, polygalacturonic acid or the monomer galacturonic acid, as well as during the infection of tomato plants. The remaining PG genes exhibit low expression levels under all the conditions tested. Secreted PG activity was decreased significantly during growth on pectin in the single deletion mutants lacking either pg1 or pgx6, as well as in the double mutant. Although the single deletion mutants did not display a significant virulence reduction on tomato plants, the Δpg1Δpgx6 double mutant was significantly attenuated in virulence. The combined action of exoPGs and endoPGs is thus essential for plant infection by the vascular wilt fungus F. oxysporum.
authors.affiliation: Departamento de Genetica, Universidad de Cordoba, Córdoba, E-14071, Spain.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Bravo Ruiz
authors.affiliation: Departamento de Genetica, Universidad de Cordoba, Córdoba, E-14071, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Di Pietro
authors.affiliation: Departamento de Genetica, Universidad de Cordoba, Córdoba, E-14071, Spain.
authors.forename: M Isabel G
authors.initials: MI
authors.lastname: Roncero
mesh_terms: D000595:Amino Acid Sequence; D005670:Fusarium / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity*; D017353:Gene Deletion; D005800:Genes, Fungal; D018551:Solanum lycopersicum / Q000382:microbiology; D009154:Mutation / Q000235:genetics; D010368:Pectins / Q000378:metabolism; D010802:Phylogeny; D011096:Polygalacturonase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D000072417:Protein Domains; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014774:Virulence
chemical_list: D012333:RNA, Messenger; D010368:Pectins; D011096:Polygalacturonase
keywords: Fusarium; endoPG; exoPG; tomato; virulence