Cloning and characterization of genes regulated during conidiation in Colletotrichum graminicola
Abstract
The maize anthracnose fungus Colletotrichum graminicola produces two distinct types of asexual spores, falcate conidia and oval conidia. This study involved cloning and characterization of genes regulated during conidium development. A cDNA library representing transcripts expressed during development of oval conidia was constructed and screened. Subsequent analyses of three cDNA clones revealed the complexity of gene expression during the developmental process, and that both developmentally-specific and spore-type specific gene regulation occurs. The SOD1 gene, which encodes a manganese-type superoxide dismutase was among the genes isolated and characterized. SOD1 is transcribed during the development of both types of conidia. Analysis of SOD1 revealed three introns and four exons which encodes a 208 amino-acid polypeptide. Transformation-mediated gene replacement was performed to create sod1 mutants to determine the functional role of SOD1. Surprisingly, sod1 mutants grew and differentiated as well as the wild-type strain in vitro, but infection assays indicated they are reduced in pathogenecity. In some cases, ectopic integration of DNA used in the SOD1 gene replacements led to the recovery of conidiation (Con$\sp-)$ mutants. Analysis of these Con$\sp-$ mutants revealed complex epistatic relationships and defined regions of the genome that appear to be essential for normal conidiation in C. graminicola.
Degree
Ph.D.
Advisors
Hanau, Purdue University.
Subject Area
Plant pathology|Molecular biology
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