Somatic segregation of the killer (k) and neutral (n) cytoplasmic genetic determinants in yeast

Abstract

When killer and neutral strains of Saccharomyces cerevisiae are crossed the resulting diploid clones possess a killer phenotype and when spored yield a complete range of tetrad ratios.The combined results of analysing tetrads and vegetative cells of diploid clones derived from two different neutral × killer crosses (K1 × N1 and K2 × N1) demonstrate that the range of tetrad ratios can be accounted for by the occurrence of somatic segregation of killer (k) cytoplasmic determinants prior to sporulation. Such results support the genetic model for the inheritance of the killer character in yeast already proposed (Somers & Bevan, 1969).During the course of these studies a correlation was found between the strengths of the killer phenotypes of diploid colonies and the proportions of killer spore cultures obtained after sporulation of their cells.