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Interaction between mitochondria derived from incompatible black Aspergillus isolates
1Department of Microbiology, Faculty of Sciences, University of Szeged, Hungary. kevei@bio.u-szeged.hu
Abstract:
As black Aspergillus isolates are highly heterokaryon-incompatible mitochondrial transmissions were performed by protoplast fusion. Donor strains with oligomycin-resistant mitochondria and sensitive recipient partners of various A. japonicus isolates were applied and the progeny were selected for oligomycin resistance and for recipient nuclear phenotype. These strains basically inherited the mitochondrial DNA of the donor strain, which might remain unchanged (substituted progeny) or might be modified by specific sequences of the recipient mtDNAs (recombinant progeny). Different mobile elements characteristic of the recipient parents were exclusively responsible for the development of the feature of recombinant mtDNAs. Substituted progeny were either stable wild-type-like strains as a result of compatible co-operation between donor mitochondria and recipient nuclei, or aconidial strains with a reduced fitness, exhibiting a certain instability. The latter type was probably due to the less compatible communication between nuclear and extrachromosomal genetic systems originating from different parents. These progeny were able to undergo some developmental (segregation) processes during subsequent cultivation, resulting in a stable, wild-type phenotype which possessed a new type of mtDNA resembling that of the acceptor parents.
Insights
Mitochondrial DNA transmission in Aspergillus was achieved through protoplast fusion. Recombinant progeny showed modified mitochondrial DNA due to recipient elements, while substituted progeny displayed varying stability and nuclear-mitochondrial compatibility.
Area of Science:
- Mycology
- Genetics
- Molecular Biology
Background:
- Black Aspergillus isolates exhibit high heterokaryon incompatibility.
- Mitochondrial inheritance in Aspergillus is complex and requires specific transmission methods.
Purpose of the Study:
- To investigate mitochondrial DNA (mtDNA) transmission and recombination in Aspergillus isolates.
- To analyze the genetic stability and compatibility of progeny resulting from protoplast fusion.
Main Methods:
- Protoplast fusion was employed for mitochondrial transmission between donor and recipient Aspergillus strains.
- Selection of progeny was based on oligomycin resistance (donor mitochondria) and recipient nuclear phenotype.
- Analysis of mitochondrial DNA in progeny to identify substituted and recombinant types.
Main Results:
- Progeny primarily inherited donor mtDNA; some remained unchanged (substituted), while others were modified (recombinant).
- Recombinant mtDNAs resulted from the incorporation of recipient-specific mobile elements.
- Substituted progeny showed either stable wild-type phenotypes or unstable, aconidial forms with reduced fitness due to nuclear-mitochondrial incompatibility.
Conclusions:
- Mobile elements play a crucial role in generating recombinant mtDNAs during protoplast fusion.
- Nuclear-mitochondrial interactions influence the stability and phenotype of resulting Aspergillus strains.
- Unstable progeny can segregate to achieve stable, wild-type phenotypes with acceptor-like mtDNA.