Efficient selection of phleomycin-resistant Saccharomyces cerevisiae transformants

The recently described dominant yeast marker Tn5ble confers phleomycin resistance on the yeast Saccharomyces cerevisiae (Gatignol, Baron and Tiraby, 1987. Mol. Gen. Genet. 207, 342-348). Incubation in non-selective medium prior to selection is critical, however, for getting phleomycin-resistant transformants. A 6-h incubation period was found to give optimal transformation frequencies, up to 10(5) transformants/micrograms plasmid, comparable to selection for uracil prototrophy (Ura+).