DNA-DNA reassociation studies of strains in the genera Rhodosporidium and Rhodotorula.

The genetic relatedness of 60 strains in the basidiomycetous yeast genera Rhodosporidium and Rhodotorula was studied by the DNA-DNA hybridization using the nitrocellulose filter technique.Degrees of the intraspecific reassociation among the DNAs from the strains of Rhodosporidium in firmominiatum, Rhodosporidium diobovatum, Rhodosporidium sphaerocarpum, and Rhodosporidium dacryoidum ranged from 64 to 99%.The mating-type strains of Rhodosporidium toruloides were divided into four homology clusters.The degrees of DNA-DNA reassociation between the mating-type strains and the self sporulating strains in Rhodosporidium toruloides were very low.(l8°) indicating the absence of relatedness between them.The strains of Rhodotorula glutinis were divided into five homology clusters.Among these strains, some, including the type strain, showed close relatedness to Rhodosporidium diobovatum, some to Rhodosporidium toruloides (self-sporulating), and some to Rhodotorula rubra, and Rhodotorula pilimanae.The strains of Rhodotorula minuta were divided into four homology clusters.A close relationship was found between some strains of Rhodotorula minuta including the type strain and a strain of Rhodotorula pallida.There was a very close relationship between the Rhodotorula sinensis strain and the strains of Rhodosporidium in firmominiatum.The DNA-DNA hybridization technique has proved valuable in determining genetic relatedness among various yeasts (1-23).Recently, the genera Rhodosporidium and Rhodotorula were found to consist of phylogenetically different strains based on the DNA base composition (24-26), the ubiquinone system (27,28), the electrophoretic patterns of enzymes (29, 30), and the cellular carbohydrate composition (28,31).