Figure 1. Schematic representation of the free amino acid composition in NADH-GOGAT mutant lines. Plants of the wild-type and 2 T-DNA insertion lines were grown on vertical MGRL agar plates²⁰ containing 7 mM nitrate as nitrogen source for 14 d before they were transferred to MGRL medium without nitrogen for 3 d. Afterwards plants were transferred to the medium supplemented with either 10 mM KNO₃ or NH₄Cl. The plants were harvested at 6 or 24 h after nitrogen supply. The concentration of amino acids in wild-type plants was compared with the 2 T-DNA insertion lines, whereas the increase or decrease is represented by different color. One-way ANOVA followed by Dunnett tests were used to identify significant differences between wild-type and T-DNA insertion lines (P < 0.05).