Enzymatic assay of ALT and AST. The assay was performed on root and leaf of plant during the progression of Fe deficiency treatment. Sampling was performed at 0, 1, 3, 7 days after Fe withdrawing. The meaning of the columns and the measurement units of enzymatic activities is as reported in Figure 2. AST activity of control (0 d) was 17 and 30 nmol NADH mg-1 prot min-1 for root and leaf, respectively. ALT activity of control (0 d) was 29 and 20 nmol NADH mg-1 prot min-1 for root and leaf, respectively (complete activity data are reported in Additional file 1). Data are means ± SE (n = 3). In the case of significant difference (P<0.05) values with different letters are statistically different.