Plant material, growth conditions and treatments
A. thaliana genotypes used were the wild type Columbia 0 (Col-0), the cad2-1 , pad2-1 and rax1-1 γECS mutants and thecad1-3 PCS mutant. Seeds were surface-sterilized by agitation in a 15% (v/v) NaClO solution for 10 min, followed by several rinses in distilled sterile water. Seeds were germinated on 0.6 % phytoagar and grown in an Araponics® hydroponic system (Araponics SA, Liège, Belgium). After 4 weeks of growth in a short-day light regime (8 h light / 16 h darkness) at 25 ºC with a modified Hoagland nutrient solution (Tocquin et al., 2003), the nutrient solution was supplemented with 0 or 3 μM HgCl2 and plants were grown for 72 h more. At harvest, shoots and roots were collected separately and stored at -80 ºC until analysis.