Figure 8.

Schematic representation of nitrogen metabolism changes occurring in Fe-deficient cucumber plants. Orange arrows indicate the specific process investigate in this work, while the arrow thickness indicates an up- or down-activation of enzymatic activities. Red arrow indicates the possible recycle of protein and aa occurring under Fe deficiency in cucumber plants. Since NO₃^- assimilation (NR activity) decreases and GS/GOGAT cycle increases in both root and leaf, the source of ammonia might come from a recycling of aa deriving from protein degradation [9]as suggested in ). The aa might be partially translocated to the leaf sustaining its metabolism as supported by data presented in this work (Figures 5 and 7).