CADMIUM, COPPER AND ZINC INDUCE THIOL-PEPTIDE PRODUCTION BUT DO NOT AFFECT GENE EXPRESSION INVOLVED IN THEIR SYNTHESIS IN ARABIDOPSIS THALIANA SEEDLINGS

The aim of this work was to investigate changes in the levels of thiol-peptide compounds related to their genetic regulation in Arabidopsis thaliana L. seedlings exposed to Cd, Cu and Zn. This species can be important for a better understanding of the mechanisms involved in metal homeostasis, detoxification and tolerance in plants. Seedlings of A. thaliana were exposed to the above metals at concentrations of 10, 5 and 150 µM, respectively. After 12 days of metal treatments, given separately or in triple combination (Cd/Cu/Zn), the shoots and roots were analyzed by HPLC for glutathione and phytochelatin levels, and by q-PCR for expression of the genes involved in their metabolism. Thiol-peptide compound production was induced by all metals, whether alone or combined. By contrast, the expression of genes involved in their synthesis (AtGSH1, AtGSH2, AtPCS1 and AtPCS2) was at no point affected by the metals, thus suggesting a post-transcriptional control of such synthesis. Our results could provide a bridge between A. thaliana responses aimed at metal detoxification and traits of fast-growing, high biomass, plants to be employed as phytoremediation tools.