Cytoplasmic inheritance of the selfing factor in the myxomycete Didymium iridis

Abstract

SUMMARYThe mechanism by which the selfing factor is inherited in the heterothallic myxomycete Di4ymium iridis has been investigated. A non-selfing isolate, Honduran A2 was crossed with two selfing isolates, Panamanian 2-4 and Panamanian 2-7. The latter two isolates bear the mating alleles A7 and A8 respectively. Meiotic segregants were then analysed for selfing frequency.Mating types were used as a nuclear marker. The capacity to self was inherited by all segregants, with the A2 segregant selfing at a higher frequency than either the A' or A8 segregant. The incidence of selfing increases in the A2 segregant as it is successively recloned. In the F, generation the frequency of selfing is observed to be 100 per cent. A cytoplasmic factor is postulated with the Honduran A' mating type being more susceptible to its action than either of the other two mating types.