The mitochondrial plasmid of the true slime mold Physarum polycephalum bypasses uniparental inheritance by promoting mitochondrial fusion.
Mitochondrial DNA (mtDNA) is inherited maternally in most eukaryotes. Linear mitochondrial plasmids in higher plants and fungi are also transmitted from the maternal parent to the progeny. However, mF, which is a mitochondrial linear plasmid of Physarum polycephalum, evades uniparental mitochondrial inheritance. We examined 36 myxamoebal strains of Physarum and isolated three novel mF+ strains (JE8, TU111, NG111) that harbored free mF plasmids. These strains were mated with the mF- strain KM88. Of the three mF- x mF+ crosses, only KM88 x JE8 displayed complete uniparental inheritance. However, in KM88 x TU111 and KM88 x NG111, the mtDNA of KM88 and mF of TU111 and NG111 were inherited by the plasmodia and showed recombination. For example, although the mtDNA of TU111 was eliminated, the mF of TU111 persisted and became inserted into the mtDNA of KM88, such that recombinant mtDNA represented 80% of the total mtDNA. The parental mitochondria fused to yield giant mitochondria with two or more mitochondrial nucleoids. The mF appears to exchange mitochondria from the recipient (paternal) to the donor (maternal) by promoting mitochondrial fusion.
Sakurai
Rakusa
R
Laboratory of Plant Life System, Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Bldg. FSB-601, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8562 Japan.
Nomura
Hideo
H
Moriyam
Yohsuke
Y
Kawano
Shigeyuki
S
D000818:Animals; D003433:Crosses, Genetic; D017931:DNA Primers; D004272:DNA, Mitochondrial / Q000235:genetics*; D003720:Densitometry; D004587:Electrophoresis, Agar Gel; D016521:Electrophoresis, Gel, Pulsed-Field; D005111:Extrachromosomal Inheritance / Q000235:genetics*; D007211:Indoles; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000378:metabolism*; D009693:Nucleic Acid Hybridization; D016839:Physarum polycephalum / Q000235:genetics* / Q000378:metabolism; D010957:Plasmids / Q000235:genetics*; D016133:Polymerase Chain Reaction; D013045:Species Specificity
D017931:DNA Primers; D004272:DNA, Mitochondrial; D007211:Indoles; C007293:DAPI