GENETIC EXCHANGE BETWEEN DIPLOID AND HAPLOID MYCELIA OF ARMILLARIA-GALLICA

In the Basidiomycotina, heterokaryotic mycelia are known to be able to heterokaryotize homokaryotic mycelia of the same species (the 'Buller phenomenon'). The present study examined the analogous process in Armillaria gallica in pairings of diploid and haploid mycelia. Restriction fragment length polymorphisms (RFLPs) were used as genetic markers to follow genetic transmission in these pairings. Hyphal tips were sampled predominantly from the area of the resident haploid in the pairings. In all cases, the mitochondrial haplotype of each sample was that of the resident haploid. Three patterns of nuclear inheritance were observed. First and most frequently hyphal tips carried diploid nuclei, which apparently had replaced the haploid nuclei. Second, hyphal tips were recombinant, carrying some, but not all, markers from both the diploid and the haploid nuclei. Third and least frequently, hyphal tips retained all nuclear markers from both the diploid and haploid in uninucleate compartments, a condition consistent with triploidy.