Salt stress increases ferredoxin‐dependent glutamate synthase activity and protein level in the leaves of tomato

Ferredoxin‐dependent glutamate synthase (EC 1.4.7.1) catalyzes an essential step in the pathway of glutamate biosynthesis. Exposing detached tomato (Lycopersicon esculentum) leaves for 6 h to 12 g l−1 NaCl resulted in a significant two‐fold increase in the activity of ferredoxin‐dependent glutamate synthase extracted from the leaves. Western blot studies demonstrated that salt treatment also increased the ferredoxin‐dependent glutamate synthase content of the leaves. A similar effect of salt on the concentration of this enzyme was found in the leaves of hydroponically‐grown tomato plants. The induction of ferredoxin‐dependent glutamate synthase under salt stress may provide the glutamate required for the proline synthesis which is a common response to salt stress.