GSE33148
Transcription factor AbVf19 induces hydrolytic enzyme genes during pathogenesis in Alternaria brassicicola
Alternaria brassicicola is a successful saprophyte and necrotrophic pathogen with a broad host range.  It produces secondary metabolites that marginally affect virulence, in contrast to many A. alternata strains that produce secondary metabolites as host-specific pathogenicity factors.  Cell wall-degrading enzymes (CWDEs) have been considered important for pathogenesis, but no CWDEs have been identified as significant virulence factors in A. brassicicola.  In this study, we discovered mutants of a gene, AbVf19, which consistently produced smaller lesions than the wild type.  The mutants grew slower than the wild type on an axenic medium with pectin as a major carbon source.  Gene expression comparisons identified several hydrolytic enzyme-coding genes being down-regulated in the mutant during a late stage of infection.  These down-regulated genes comprised a small fraction of genes within each family.  Three of these genes had mutants that showed no or little change in virulence.  This suggested that each down regulated gene only made a small contribution to virulence, or that their functions were redundant.  This study demonstrated the existence and importance of a transcription factor that regulates a suite of genes that are probably important for decomposing and utilizing plant material during the late stage of plant infection. Overall design: gene expression profile comparisons between wild type and a transcription factor mutant during host infection