@article{mbs:/content/journal/micro/10.1099/00221287-111-2-271, author = "Yamazaki, Toyohiko and Oshima, Yasuji", title = "Direct Diploidization and Occurrence of Polyploidy in Saccharomycodes ludwigii", journal= "Microbiology", year = "1979", volume = "111", number = "2", pages = "271-281", doi = "https://doi.org/10.1099/00221287-111-2-271", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-111-2-271", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", abstract = "In a haploid cell culture of Saccharomycodes ludwigii, sporogenous diploid cells homozygous for all the genetic markers including mating type were effectively discriminated on a dye plate consisting of 15 μg trypan blue and 10 μg phloxine B ml−l in synthetic nutrient medium. The diploid cells appeared at a frequency of about 5 × 103 that of the haploid cells and those tested bore the same alleles as the original haploid cells. The low frequency of prototrophic colonies (approximately 1 × 10−8 in a mass mating culture of two different haploid strains of identical mating type and complementary auxotrophic traits, and the morphological changes observed during the suspected diploidizing process suggest that the homozygous diploids originate by direct diploidization in haploid cells. From the diploid cells homozygous for mating type, triploid and tetraploid cells were easily constructed. As with diploid cells, tetrad data from these polyploid clones suggested the absence of crossing-over at meiosis.", }