"Isozyme variation in ""helminthosporium-type"" species pathogenic on maize"
Simcox, Kevin Dean
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Permalink
https://hdl.handle.net/2142/19582
Description
Title
"Isozyme variation in ""helminthosporium-type"" species pathogenic on maize"
Author(s)
Simcox, Kevin Dean
Issue Date
1989
Doctoral Committee Chair(s)
Pedersen, Wayne L.
Department of Study
Crop Sciences
Discipline
Crop Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Plant Pathology
Language
eng
Abstract
The population structure of three species of fungi pathogenic on Zea mays L.; Cochliobolus carbonum, C. heterostrophus, and Septosphaeria turcica were studied using isozyme analysis. Forty isolates of S. turcica were evaluated using nineteen enzyme stains. Polymorphisms were identified with aspartate aminotransferase (EC 2.6.1.1), fumarase (EC 4.2.1.2), glucose-6-phosphate dehydrogenase (EC 1.1.1.49), and mannose-6-phosphate isomerase (EC 5.3.1.8). Associated electrophoretic and virulence phenotypes were found, indicating that populations exist in S. turcica as asexually propagated clonal groups. Use of the UPGMA method to calculate overall similarity between isolates found that isolates of race 1 were more similar to race 2 than isolates of race 3.
Isolates of C. carbonum were found to be polymorphic for aspartate aminotransferase, esterase (EC 3.1.1), glucose phosphate isomerase (EC 5.3.1.9), leucine aminopeptidase (EC 3.4.11), and mannitol dehydrogenase. Races of C. carbonum were found to be associated with specific electrophoretic phenotypes. Phenograms generated by the UPGMA method showed similarity between races 1 and 3, which are highly virulent on maize. Both races were less similar to isolates of race 2, a weak pathogen of maize. No isozyme polymorphisms were detected in isolates of race 0 of C. heterostrophus. One race T isolate showed polymorphisms with esterase and hexokinase.
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