The double T-DNA insertion mutant m19m23 is hypersensitive to zinc deficiency. (A) Effect of zinc deficiency on 3-week-old seedlings of Arabidopsis (WT), bZIP19 T-DNA insertion mutants (m19), bZIP23 T-DNA insertion mutants (m23), and double T-DNA insertion mutants (m19m23) grown in MS medium without (Zn-) and with 30 μM ZnSO4 (Zn+). (B) Effect of zinc supply on 4-week-old plants of Arabidopsis (WT), m19, m23, and m19m23, grown in hydroponics at 0.05 μM (Zn-), 2 μM (Zn+), and 25 μM ZnSO4 (Zn++). (C) Zinc concentration, in mg·kg−1 of dry weight, and dry weight (DW), in g, of shoots (gray bars) and roots (white bars) of 4-week-old WT, m19, m23, and m19m23 plants, grown in hydroponics at 0.05 μM ZnSO4 (Zn-). *, P < 0.05; **, P < 0.01; ***, P < 0.001; representing significant differences of the mean in comparison with the WT mean (mean ± SEM).