title: Association of Effector Six6 with Vascular Wilt Symptoms Caused by Fusarium oxysporum on Soybean.
abstract: The Fusarium oxysporum species complex (FOSC) is a widely distributed group of fungi that includes both pathogenic and nonpathogenic isolates. In a previous study, isolates within the FOSC collected primarily from soybean were assessed for the presence of 12 fungal effector genes. Although none of the assayed genes was significantly associated with wilt symptoms on soybean, the secreted in xylem 6 (Six6) gene was present only in three isolates, which all produced high levels of vascular wilt on soybean. In the current study, a collection of F. oxysporum isolates from soybean roots and F. oxysporum f. sp. phaseoli isolates from common bean was screened for the presence of the Six6 gene. Interestingly, all isolates for which the Six6 amplicon was generated caused wilt symptoms on soybean, and two-thirds of the isolates showed high levels of aggressiveness, indicating a positive association between the presence of the effector gene Six6 and induction of wilt symptoms. The expression profile of the Six6 gene analyzed by quantitative reverse-transcription polymerase chain reaction revealed an enhanced expression for the isolates that caused more severe wilt symptoms on soybean, as established by the greenhouse assay. These findings suggest the suitability of the Six6 gene as a possible locus for pathogenicity-based molecular diagnostics across the various formae speciales.
authors.affiliation: First and third authors: Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, 29122 Piacenza, Italy; first and fourth authors: Department of Plant Pathology and Microbiology, Iowa State University, Ames 50011; and second author: Department of Plant Science, California State University, Fresno 93740.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Lanubile
authors.affiliation: First and third authors: Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, 29122 Piacenza, Italy; first and fourth authors: Department of Plant Pathology and Microbiology, Iowa State University, Ames 50011; and second author: Department of Plant Science, California State University, Fresno 93740.
authors.forename: Margaret L
authors.initials: ML
authors.lastname: Ellis
authors.affiliation: First and third authors: Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, 29122 Piacenza, Italy; first and fourth authors: Department of Plant Pathology and Microbiology, Iowa State University, Ames 50011; and second author: Department of Plant Science, California State University, Fresno 93740.
authors.forename: Adriano
authors.initials: A
authors.lastname: Marocco
authors.affiliation: First and third authors: Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, 29122 Piacenza, Italy; first and fourth authors: Department of Plant Pathology and Microbiology, Iowa State University, Ames 50011; and second author: Department of Plant Science, California State University, Fresno 93740.
authors.forename: Gary P
authors.initials: GP
authors.lastname: Munkvold
mesh_terms: D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics*; D005670:Fusarium / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D005838:Genotype; D027805:Phaseolus / Q000382:microbiology*; D010641:Phenotype; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology*; D018517:Plant Roots / Q000382:microbiology; D018547:Plant Stems / Q000382:microbiology; D017422:Sequence Analysis, DNA; D013025:Glycine max / Q000382:microbiology*
chemical_list: D004271:DNA, Fungal; D005656:Fungal Proteins