Uniparental mitochondrial transmission in sexual crosses in Cryptococcus neoformans

Restriction fragment length polymorphism (RFLP) in the large ribosomal RNA region of the mitochondrial DNA (mtDNA) was developed as a genetic marker f or investigating mitochondrial transmission in sexual crosses of the human pathogenic basidiomycetous yeast Cryptococcus neoformans. Strain JEC20 of C . neoformans var. neoformans (mat a) was mated with six strains of C. neofo rmans var. grubii (mat alpha). Successful mating was indicated by the forma tion of hyphae and basidiospores. These basidiospores were examined for mtD NA RFLP genotypes. All 570 basidiospores examined from the six crosses show ed the mtDNA genotype of strain JEC20. The failure to recover the C. neofor mans var. grubii mtDNA in any cross indicates that the C. neoformans var. g rubii mtDNA is either selectively eliminated in the newly formed dikaryon o r selectively excluded in the immediate dikaryotic hyphae of the newly form ed dikaryon.