QUANTITATIVE DIFFERENCES OF NUCLEAR-DNA CONTENTS AND THEIR TAXONOMIC IMPLICATIONS IN LEUCOSPORIDIUM-SCOTTII, RHODOSPORIDIUM-TORULOIDES, ANDRELATED BASIDIOMYCETOUS YEASTS

Estimates of the nuclear DNA (nDNA) content in the yeast cells of 43 s trains of Leucosporidium scottii, Rhodosporidium toruloides, and relat ed yeast taxa were analyzed by fluorescence microscope photometry. Qua ntitative differences of nDNA contents occur among 18 strains of L. sc ottii. Four groups of strains with similar nDNA content were recogniza ble in L. scottii. One group contained only one strain (IFO 9474) whic h was characterized by the Q-7 system. The respective strains of the r emaining three groups had either Q-9 or Q-10 as the major ubiquinone s ystem, except CBS 8188 having both of these. Some mating strains of L. scottii had almost twice the amount of nDNA as the presumed haploid v alue. In contrast, both mating type A and a strains of R. toruloides h ad nearly identical average nDNA contents. Our results suggest the pre sence of aneuploidy among yeast cells of L. scottii.