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Uniparental Mitochondrial Transmission in the Cultivated Button Mushroom, Agaricus bisporus
1Centre for Plant Biotechnology, Department of Botany, University of Toronto, Erindale Campus, Mississauga, Ontario L5L 1C6, Canada.
Abstract:
A uniparental mitochondrial (mt) transmission pattern has been previously observed in laboratory matings of the cultivated mushroom Agaricus bisporus on petri dishes. In this study, four sets of specific matings were further examined by taking mycelial plugs from the confluent zone of mated homokaryons and inoculating these plugs into rye grain for laboratory fruiting and for fruiting under industrial conditions. Examination of the mt genotype of each individual fruit body for mt-specific restriction fragment length polymorphisms further confirmed that the mt genome was inherited uniparentally. The vegetative radial growth and the fruiting activity of two pairs of intraspecific heterokaryons, each pair carrying the same combination of nuclear genomes but different mt genotypes, were compared. Our results suggested that the mt genotype did not appreciably affect radial growth or fruiting activity. The failure to recover both heterokaryons, each carrying either parental mt genotype in any given cross, therefore clearly indicated that in matings of A. bisporus, the mt genome from one of the parental homokaryons is either selectively excluded in the newly formed heterokaryon or selectively eliminated in the immediate heterokaryotic mitotic progeny of the newly formed heterokaryon.
Insights
Mitochondrial DNA in the mushroom Agaricus bisporus is uniparentally inherited, with one parent's mitochondrial genome being excluded or eliminated during mating. This pattern does not affect mushroom growth or fruiting.
Area of Science:
- Mycology
- Genetics
- Molecular Biology
Background:
- Uniparental mitochondrial (mt) transmission has been observed in laboratory matings of Agaricus bisporus.
- Understanding mt inheritance is crucial for fungal breeding and cultivation.
Purpose of the Study:
- To confirm uniparental mt transmission in Agaricus bisporus under laboratory and industrial fruiting conditions.
- To investigate the impact of different mt genotypes on fungal growth and fruiting.
- To elucidate the mechanism of mt genome exclusion or elimination during heterokaryon formation.
Main Methods:
- Mating of homokaryons and inoculation of mycelial plugs into rye grain for fruiting.
- Analysis of mt genotypes in fruit bodies using restriction fragment length polymorphisms (RFLP).
- Comparison of vegetative radial growth and fruiting activity between heterokaryons with different mt genotypes.
Main Results:
- Uniparental mt inheritance was confirmed in all examined fruit bodies.
- No significant effect of mt genotype on radial growth or fruiting activity was observed.
- Failure to recover both parental mt genotypes in heterokaryotic progeny indicated selective exclusion or elimination.
Conclusions:
- The mt genome of Agaricus bisporus is uniparentally inherited.
- The specific mt genotype does not influence vegetative growth or fruiting capabilities.
- One parental mt genome is either excluded or eliminated during heterokaryon formation and subsequent mitotic divisions.
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