Peroxidase isoenzymes ionically bound to the cell wall of the hypocotyl. Seedlings were grown in the presence (+) or absence (−) of cadmium and harvested at 10 and 18 d old. (A, B) After IEF, the peroxidase activity was revealed in the presence of gaïacol (A) or chloronaphthol (B). A similar amount of PER (0·1 nkatal) activity was loaded per well, each sample being repeated in two successive wells. The pH values measured with a surface electrode are given on the left. Note the increase with age and Cd of the isoforms N and Ba. (C) Expression of Flxper genes compared with elongation factor gene LuEF1 α (EF1) as seen by PCR. All gel figures were representative of three to five repeats. A, N and B are acidic, neutral and basic isoforms, respectively.