Pleiotropic Mutants Hypersensitive to Heavy Metals and to Oxidative Stress in Chlamydomonas Reinhardtii

Insertional mutagenesis was used in Chlamydomonas reinhardtii to isolate original mutants hypersensitive to multiple drugs and physical agents. Out of 5200 transformants analyzed, 13 mutants belonging to seven phenotypic classes were isolated. Five were exclusively sensitive to cadmium and represented two loci. The other mutants were pleiotropic and presented a cross sensitivity to several (2--6) of the following agents: cadmium, copper, lead, paraquat, hydrogen peroxide, UVC and light. In all mutants analyzed, the hypersensitive phenotype was most probably due to a single mutational event. The sensitivity of several pleiotropic mutants to a broad range of physical and chemical agents suggests that the disrupted genes are involved in multiple stress responses.