Abstract
Phytochelatin has been shown to play an important role in cadmium(Cd) detoxification. To explore a novel mechanism for Cd tolerance, we screened for a carbon ion beam mutagenized Arabidopsis population and identified a novel mutant, Cadmium-sensitive mutant 1 (cds1). Using 1275 lines of F2 plants, cds1 was localized to approximately 70kbp region of chromosome 4, which contained 27 genes. We sequenced coding sequences of the 27 genes and found a 2.5kbp-deletion that disturbed two genes. Expression of the two genes was not detected in cds1 by RT-PCR. Between the two genes, the gene encoded shikimate kinase family protein (AtSK2)could rescue cds1 phenotype, suggesting that AtSK2 is the casual gene of cds1 mutant. Shikimate kinase is the enzyme works in the shikimate pathway. To our knowledge, this is the first report showing that shikimate kinase is involved in Cd tolerance in plants. There have been reports showing that accumulation of some metabolites of shikimate pathway is enthanced by Cd exposure and that exogenously applied salicylic acid and tryptophan increased Cd tolerance. These results suggest that shikimate pathway could play an important role in Cd tolerance in plants.
