ULTRAVIOLET LIGHT SENSITIVE MUTANTS OF USTILAGO VIOLACEA

Abstract

Nine UV-sensitive mutants of U. violacea have been isolated and shown by analysis of complementation and recombination to represent four to five genes. Genes uvs-1 and uvs-3, unlike the other genes and the wild type, are incapable of postirradiation recovery on water agar and are therefore assumed to be deficient in dark repair. Gene uvs-2 does not affect dark repair but may affect photoreactivation. Mutants u7 and u9 which may represent one to two genes are defective in photoreactivation but not in dark repair. The dark recovery process on water agar is inhibited by caffeine.The survival of UV-sensitive mutants during intergenic complementation in a dicaryon was close to that of the wild type. This efficient complementation establishes that the repair enzymes are freely diffusible in the cytoplasm. None of the mutants are linked closely to each other or to the other marker genes used.