Isolation and characterization of chlorate resistant mutants from nitrate-nonutilizing fungusPhycomyces blakesleeanus |
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Authors: | Joe Fukui Atsushi Miyazaki Tamotsu Ootaki |
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Institution: | (1) Institute of Genetic Ecology, Tohoku University, 2-1-1, Katahira, Aoba-ku, 980-8577 Sendai, Japan |
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Abstract: | Chlorate resistant mutants, which were first isolated in the zygomycetous fungusPhycomyces blakesleeanus, were found to be resistant up to a concentration of at least 300 mM of potassium chlorate. The dose-response relationship
showed that although the mutants could be divided into two groups based on chlorate resistance in the mycelial elongation
assay on the solid minimal medium, this was not observed in the assay using liquid culture. Genetic analysis of heterokaryons
revealed the mutant alleles to be dominant. Enzymatic activities of three nitrate reductases and chlorate reductase were deficient
in both the parent strain and the mutants. Intracellular incorporation of chlorate ion varied from strain to strain; however,
the variation could not explain the mechanism of chlorate resistance. One unexpected characteristic of the mutants was that
the intracellular sulfate ion concentration was 3.5 to 5.5 times higher than in the parent strain. We designated this mutant
genotypecrw, chlorate resistant mutant from nitrate-nonutilizing wild type. |
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Keywords: | chlorate resistance dominant mutation nitrate reductase Phycomyces blakesleeanus Zygomycetes |
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