Division of Plant Pathology and Microbiology in Plant Sciences Department
Research project:

Evolution of pathogenicity factors and the conditionally dispensible (CD) chromosomes in Nectria haematococca MPVI


This pathogen of pea contains an enzyme (pisatin demethylase) that detoxifies the phytoalexin (pisatin), which is produced to deter fungal infections. Only strains of this fungus that have this ability can colonize pea and cause significant disease. This gene resides on a small chromosome that can be lost, with the only evident phenotypic change being the loss of the ability to be a pathogen of pea. This project investigates the origin of pisatin demethylase, which is a P450 cytochrome, and thus a member of a huge gene superfamily. A gene genealogical approach will indicate when this P450 diverged and evolved the ability to detoxify pisatin, and whether the known orthologs of this gene found in polyphyletic pathogens of pea were inherited vertically from a common ancestor, or gained by horizontal gene transfer in a common infection court. Additional studies are investigating the structure and inferring the origin of the conditionally dispensable chromosome, which is part of the larger project to sequence the genome of this fungus.

   
For more information: Dr. Scott Kroken, kroken@ag.arizona.edu
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