FIGURE 4.

Growth of a Tnt1-Mt-mutant carrying an insert in the cds of Medtr1g084050 (nicotianamine synthase-like protein). Three-week old nodulated plants of the mutant were transferred to glass tubes with N-free nutrient solution. The plants received a low (0.25 mM) ammonium start-N supply during the first week of growth in the tubes and relied exclusively on N₂ fixation for the next 7 days. During the subsequent 2 weeks, for one set of plants the nutrient solution was adjusted once a week to 5 mM nitrate concentration, while the other plants relied solely on nitrogen fixation. (A) Shows nitrate (left) and N₂-supplied (right) plants at the end of the growth period. (B–E) Show fully expanded leaves of nitrogen fixation (right) or nitrate-dependent (left) plants 0, 7, 10, and 14 days after the beginning of the nitrate supply.