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Signal transduction and genetic relatedness in Colletotrichum trifolii
Abstract
Colletotrichum trifolii Bain is the causal agent of alfalfa anthracnose, and exhibits race-cultivar specificity. The involvement of cell-signalling between host and pathogen during recognition and disease development is unknown. A ubiquitous set of signalling molecules found in other eukaryotic systems is the protein kinases. Protein kinases mediate the extracellular and intracellular transduction of signals in eukaryotic cells. Fungal protein kinase genes may be involved in environmental, developmental and pathogenic signal pathways. This study characterized the presence of a putative protein kinase gene in the phytopathogenic fungus C. trifolii. A 5-kilobase (Kb) Pstl fragment containing the protein kinase gene was isolated from the Race 1 genomic library of C. trifolii. The gene was sequenced and partially characterized. Numerous conserved eukaryotic regulatory domains were identified within the 5$\sp\prime$ region of the gene. A putative leucine zipper, a proline-rich region and a glutamine-rich region were identified, all of which have been documented to be associated with transcriptional activators. In addition, one major and three minor transcriptional start sites were defined. RNA blot analysis indicates the transcript for the gene to be approximately 2.3 Kb. Both races of the fungus express this transcript at a low constitutive level within vegetative mycelium. Significant expression is found during spore germination, and this gene appears to be developmentally regulated. The leucine zipper motif, and glutamine- and proline-rich regions within this gene may be involved in this developmental expression. In addition to this research, studies were initiated to analyze genetic relatedness among the Colletotrichum. Seven strains of five different Colletotrichum species were analyzed for vegetative compatibility groups (VCG). Nitrate non-utilizing mutants were used to test for VCG relatedness. The five heterokaryon self-compatible strains were all in distinct vegetative compatibility groups. This would indicate that the Colletotrichum genus is genetically diverse and significantly limited in terms of genetic exchange.
Subject Area
Plant pathology|Molecular biology
Recommended Citation
Brooker, Nancy Louise, "Signal transduction and genetic relatedness in Colletotrichum trifolii" (1992). ETD collection for University of Nebraska-Lincoln. AAI9237654.
https://digitalcommons.unl.edu/dissertations/AAI9237654