Transmission Pattern of Mitochondrial DNA during Plasmodium Formation in Physarum polycephalum

Abstract

The transmission pattern of mitochondrial DNA (mtDNA) was studied during plasmodium formation in Physarum polycephalum. Plasmodia were generated by matings between pairs of amoebal strains carrying mtDNA molecules that were distinguishable by restriction endonuclease digestion. The transmission of mtDNA was uniparental in every case; the plasmodia always carried mtDNA with the restriction pattern of only one of the two parental types. In each mating pair, one strain consistently acted as mtDNA donor, but this strain did not always act as mtDNA donor when combined in other mating pairs. The identity of the mtDNA donor in each pair was not determined by the different types of mtDNA molecules present or by different alleles of matB or matC, two mating-type loci which regulate amoebal fusion. The results suggested that alleles of a third mating-type locus, matA, which controls zygote development, might form a hierarchy such that the mtDNA donor in any cross would be the strain of higher status. The deduced hierarchy was matA2 > matA11 > matA12 > matA1.