title: A zinc-finger-family transcription factor, AbVf19, is required for the induction of a gene subset important for virulence in Alternaria brassicicola.
abstract: Alternaria brassicicola is a successful saprophyte and necrotrophic plant pathogen with a broad host range within the family Brassicaceae. It produces secondary metabolites that marginally affect virulence. Cell wall-degrading enzymes (CDWE) have been considered important for pathogenesis but none of them individually have been identified as significant virulence factors in A. brassicicola. In this study, knockout mutants of a gene, AbVf19, were created and produced considerably smaller lesions than the wild type on inoculated host plants. The presence of tandem zinc-finger domains in the predicted amino acid sequence and nuclear localization of AbVf19-reporter protein suggested that it was a transcription factor. Gene expression comparisons using RNA-seq identified 74 genes being downregulated in the mutant during a late stage of infection. Among the 74 downregulated genes, 28 were putative CWDE genes. These were hydrolytic enzyme genes that composed a small fraction of genes within each family of cellulases, pectinases, cutinases, and proteinases. The mutants grew slower than the wild type on an axenic medium with pectin as a major carbon source. This study demonstrated the existence and the importance of a transcription factor that regulates a suite of genes that are important for decomposing and utilizing plant material during the late stage of plant infection.
authors.affiliation: Plant and Environmental Protection Sciences, University of Hawaii at Manoa, 3190 Maile Way, St. John 317, Honolulu 96822, USA.
authors.forename: Akhil
authors.initials: A
authors.lastname: Srivastava
authors.forename: Robin A
authors.initials: RA
authors.lastname: Ohm
authors.forename: Lindsay
authors.initials: L
authors.lastname: Oxiles
authors.forename: Fred
authors.initials: F
authors.lastname: Brooks
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Lawrence
authors.forename: Igor V
authors.initials: IV
authors.lastname: Grigoriev
authors.forename: Yangrae
authors.initials: Y
authors.lastname: Cho
mesh_terms: D000528:Alternaria / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D017360:Arabidopsis / Q000235:genetics / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001937:Brassica / Q000382:microbiology; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal / Q000502:physiology; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D008969:Molecular Sequence Data; D009154:Mutation; D010935:Plant Diseases / Q000382:microbiology; D013172:Spores, Fungal; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014774:Virulence
chemical_list: D029681:Arabidopsis Proteins; D005656:Fungal Proteins; D014157:Transcription Factors; D003577:Cytochrome P-450 Enzyme System; C417307:PAD3 protein, Arabidopsis