A GAL4-like protein is involved in the switch between biotrophic and necrotrophic phases of the infection process of Colletotrichum lindemuthianum on common bean.      .
Random insertional mutagenesis was conducted with the hemibiotrophic fungus Colletotrichum lindemuthianum, causal agent of common bean anthracnose. Nine mutants that were altered in their infection process on the host plant were generated. One of these, H433 is a nonpathogenic mutant able to induce necrotic spots on infected leaves rapidly. These spots are similar to those observed during the hypersensitive reaction. Cytological observations showed that the development of the mutant H433 is stopped at the switch between the biotrophic and the necrotrophic phases. This mutant carries two independent insertions of the transforming plasmid pAN7-1. Complementation studies using the wild-type genomic regions corresponding to the two insertions showed that one is responsible for the H433 phenotype. Sequencing analysis identified a single open reading frame that encoded a putative transcriptional activator belonging to the fungal zinc cluster (Zn[II](2)Cys(6)) family. The corresponding gene was designated CLTA1 (for C. lindemuthianum transcriptional activator 1). Expression studies showed that CLTA1 is expressed in low amounts during in vitro culture. Targeted disrupted strains were generated, and they exhibited the same phenotype as the original mutant H433. Complementation of these disrupted strains by the CLTA1 gene led to full restoration of pathogenicity. This study demonstrates that CLTA1 is both a pathogenicity gene and a regulatory gene involved in the switch between biotrophy and necrotrophy of the infection process of a hemibiotrophic fungus.
Dufresne
M
M
Laboratoire de Phytopathologie Moléculaire, Centre de Recherche sur les Plantes, Université Paris-Sud, 91405 Orsay Cedex, France. marie.dufresne@bbsrc.ac.uk
Perfect
S
S
Pellier
A L
AL
Bailey
J A
JA
Langin
T
T
D000595:Amino Acid Sequence; D001483:Base Sequence; D020231:Colletotrichum / Q000235:genetics* / Q000472:pathogenicity; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D004268:DNA-Binding Proteins; D007887:Fabaceae / Q000382:microbiology*; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal / Q000235:genetics; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009154:Mutation; D010641:Phenotype; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology; D010946:Plants, Medicinal; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics; D014774:Virulence / Q000235:genetics
C419692:CLTA1 protein, Colletotrichum lindemuthianum; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors