clk1, a serine/threonine protein kinase-encoding gene, is involved in pathogenicity of Colletotrichum lindemuthianum on common bean.
A random insertional mutagenesis in Colletotrichum lindemuthianum, the causal agent of common bean anthracnose, generated four mutants that showed altered pathogenicity when tested on intact seedlings, excised leaves, and/or excised hypocotyls. One of these mutants, H290, produced very few lesions on bean leaves and appeared affected in its ability to penetrate the leaf cuticle. Molecular analyses showed that the border sequences of the unique integration site of the disrupting pAN7-1 plasmid in the mutant exhibited homology with conserved domains of serine/threonine protein kinases. The corresponding wild-type sequences were cloned and a gene replacement vector with a mutated copy harboring a selection marker constructed. Transformation of the wild-type pathogen produced a strain with a phenotype identical to the original mutant. Genomic and cDNA sequences indicated that the disrupted gene is a member of the serine/threonine protein kinase family. The gene, called clk1 (Colletotrichum lindemuthianum kinase 1), was weakly expressed in the mycelium of the wild-type strain grown on rich and minimal synthetic media but was undetectable during the infection even when a sensitive reverse transcriptase-polymerase chain reaction methodology was used. This study represents the first characterization of altered pathogenicity mutants in C. lindemuthianum produced by random mutagenesis and demonstrates the involvement of a member of the serine/threonine kinase gene family in the early steps of the infection process.
Dufresne
M
M
Laboratoire de Phytopathologie Moléculaire, Université Paris-Sud, Orsay, France. dufresne@sidonie.ibp.u-psud.fr
Bailey
J A
JA
Dron
M
M
Langin
T
T
D000595:Amino Acid Sequence; D001483:Base Sequence; D029742:Caenorhabditis elegans Proteins; D004274:DNA, Recombinant; D007887:Fabaceae / Q000382:microbiology*; D005822:Genetic Vectors; D015801:Helminth Proteins / Q000235:genetics* / Q000378:metabolism; D003904:Mitosporic Fungi / Q000472:pathogenicity*; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D010641:Phenotype; D010946:Plants, Medicinal; D017386:Sequence Homology, Amino Acid; D014774:Virulence / Q000235:genetics
C104339:CLK-1 protein, C elegans; D029742:Caenorhabditis elegans Proteins; D004274:DNA, Recombinant; D015801:Helminth Proteins