The Construction and Genetic Analysis of Polyploids and Aneuploids of the Pentose-fermenting Yeast, Pachysolen tannophilus

Division of Biological Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada ABSTRACT SUMMARY: Triploid and aneuploid strains of the xylose-fermenting yeast Pachysolen tannophilus were constructed. This species is a strongly homothallic organism in which the haploid phase normally predominates. The technique for producing polyploids involved prototrophic selection and interruption of the normal sequence of events leading from nuclear fusion to meiosis. Confirmation of triploidy was obtained by tetrad analysis. The haploid chromosome number of P. tannophilus was estimated to be between 5 and 7.