THE GENETIC EXPRESS-TEST FOR DISCRIMINATION BETWEEN HAPLOIDS AND AUTODIPLOIDS IN YEAST

  • 1 January 1983
    • journal article
    • research article
    • Vol. 19  (12) , 1934-1940
Abstract
Some originally haploid strains of yeast Peterhof breeding stocks obtained in tetrad analysis of diploids turned out to be spontaneous autodiploids after storage. They produced polyploid hybrids, as shown by tetrad analysis. An express test for discrimination between haploids and autodiploids, based on the frequency of mitotic homozygotization for a recessive marker was developed. It is 10-100 times higher in heterozygous diploids than in duplex triploids. Tester strains bearing selective recessive lys2, sup1 or sup2 markers were obtained. The hybrids of the tester strains and those to be tested were plated on media selective for mitotic segregants homozygous for lys2 (medium with .alpha.-aminoadipic acid and lysine) or sup1, sup2 (medium without adenine, while the hybrid was homozygous for ochre nonsense ade1-6 suppressible by sup1 or sup2); UV-induced mitotic homozygotization was scored. By this method, it was shown that spontaneous autodiploids constitute 70% of strains under investigation in Peterhof breeding stocks.