Isolation and genetical and biochemical characterization of mutants resistant to the alkaloid lycorine.

Mutants resistant to 200 micrograms/ml of the alkaloid lycorine (LYCR) in non-fermentable substrate were isolated after nitrosoguanidine mutagenesis. Tetrad analysis and growth of heterozygous (LYCR/lycS) diploids from two different mutants revealed that a single nuclear and dominant mutation is responsible for the resistant phenotype. In the wild type total protein synthesis is only slightly inhibited, whereas DNA and RNA synthesis is lowered to about 30% of the control. In the lycorine resistant mutants all macromolecular syntheses are unaffected by the drug.