CYTOPLASMIC INSTABILITY OF THE INTERSPICIFIC YEAST HYBRID (SACCHAROMYCES GLOBOSIS X SACCH. CEREVISIAE)

Abstract

The interspecific hybrid Sacch. globosus X Sacch. cerevisiae has been produced by mating the cells of the haploid strain of Sacch. cerevisiae (the a mating type) genetically marked with a mutation causing the pink colour of the colony to the spores of Sacch. globosus. The white colour of the colony and the capability of sucrose fermentation were the criteria for the selection of hybrid zygotes. The isolated hybrid exhibits a considerable cytoplasmic instability, the respiration-deficient cells (cytoplasmic aer-mutants) frequently appearing in the course of the vegetative reproduction. The high mutability of the hybrid is manifested only on a solid medium; cultures grown on a liquid medium proved to be stable. The phenomenon described is considered to be an instance of mutability being increased by hybridization.