Mitochondrial inheritance inAspergillus nidulans

Abstract

Mitochondrial chloramphenicol and oligomycin resistance mutations were used to investigate mitochondrial inheritance in A. nidulans. Mitochondrial RFLPs could not be used to distinguish between paternal and maternal mitochondria because none were detected in the 54 isolates investigated. Several thousand ascospores from each of 111 hybrid cleistothecia from 21 different crosses between 7 heterokaryon incompatible isolates were tested for biparental inheritance. All mitochondrial inheritance was strictly uniparental. Not one instance of paternal inheritance of mitochondria was observed. The implications of our results for the theory that uniparental inheritance evolved to avoid cytoplasmic conflict are discussed. Possible explanations for the maintenance of strict uniparental inheritance of mitochondria in an inbreeding homothallic organism are suggested. The chloramphenicol resistance marker was inherited preferentially to the oligomycin resistance marker probably due to the inhibited energy production of mitochondria with the oligomycin resistance mutation. The maternal parent was determined for 93 hybrid cleistothecia from 17 crosses between 7 different strains. Contrary to previous reports A. nidulans strains functioned as both maternal and paternal parent in most crosses.

Intra- and Interspecies Virus Transfer in Aspergilli via Protoplast Fusion

“…Mutated strains N522 and N909 (see below) were derived from N400. The A. nidulans strains were isolated from soil samples from Birmingham, England, in 1992(Coenen et al, 1996.…”

Recombination of mitochondrial DNAs following transmission of mitochondria among incompatible strains of black Aspergilli

“…During this sequence, the extranuclear genomes, including mtDNAs, generally do not recombine, because of their strict uniparental inheritance (Birky 1978(Birky , 1983(Birky , 1994. Most fungi and other eukaryotic microbes are characterised by predominantly maternal inheritance of their cytoplasmic DNAs, as has been reported in many cases (Rowlands and Turner 1976;Brasier and Kirk 1986;Martin 1989;Specht et al 1992;Wilch et al 1992;Lee and Taylor 1993;Whittaker et al 1994;Chung et al 1996;Coenen et al 1996). There are only a few exceptions known where paternal inheritance of extranuclear genomes also occurs.…”

Factors affecting the spread of double-stranded RNA viruses in Aspergillus nidulans

“…a Results for ascospores are shown per cleistothecium. b Strain marked L is the strain from which progeny inherited their mitochondria (Coenen et al, 1996). c Strains 701 and 704 have different alleles for three het genes.…”

“…Protoplast fusion was performed as described previously (Coenen et al, 1996). For interspecies virus transmission protoplasts of a virus-containing ade or nia A. niger donor strain and a wild-type A. nidulans acceptor strain were fused.…”