EN
Although some genes involved in heavy metal detoxification and tolerance have been identified in plants, the mechanisms underlying heavy metal resistance remain to be elucidated further. To investigate its molecular mechanisms, a forward genetic screen was performed for identifying Arabidopsis (Arabidopsis thaliana) cadmium (Cd)-sensitive mutants. Here we report a novel cms1-1 (cadmium-sensitive) mutant, which defines a genetic locus involved in the regulation of cadmium and lead (Pb) resistance in Arabidopsis. cms1-1 plants were hypersensitive to Cd but resistant to Pb as well as oxidative stress mediated by hydrogen peroxide and methyl viologen. Genetic analysis indicated that cms1-1 is a recessive mutation in a single nuclear gene. When subjected to Cd or Pb stress, higher Cd or lower Pb content was detected in cms1-1 plants than in wild-type plants, respectively. The cms1-1 mutation altered the expression pattern of some Cd/ Pb stress-related genes, including AtPDR8 and AtPDR12, which was associated with changes of Cd and Pb contents. In addition, Cd hypersensitivity/enhanced Pb resistance mediated by cms1-1 is glutathione (GSH)- independent. The results suggest that CMS1 plays distinct roles in the regulation of Cd and Pb resistance mainly through a GSHindependent AtPDR12/AtPDR8-mediated mechanism.