Abstract
Phytochelatin (PC) has been shown to play an important role in heavy metal detoxification. However, Arabidopsis transgenic plants overexpressing the PC synthase gene failed to show an increase in Cd tolerance. To explore a novel heavy metal detoxification mechanism, we screened for an Arabidopsis Cd-sensitive mutant (cds1) by carbon ion beam mutagenesis, which causes large base pair deletions at random loci in the genome. Genetic analyses and GSH synthesis inhibitor studies revealed that the cds1 phenotype was different from those of PC synthesis mutants. Moreover, Cd content in shoots of cds1 cultured on Cd-containing media was similar to wild type, suggesting that Cd-sensitive phenotype of cds1 was not attributed to the Cd transport system from roots to shoots. In the rough mapping, cds1 was localized to approximately 300kbp region of chromosome 4. One of the genes was found to have a 2.5kbp deletion in the promoter region.
