Nitrite utilization in the roots of higher plants

Nitrite utilization by the roots of kidney bean, corn, and sunflower plants was investigated using 15N-labeled nitrite, and the following were concluded. (1) The primary roots of the corn plant assimilate nitrite to amino acids by a combination of nitrite reductase, glutamine synthetase and glutamate synthase. The reduction rate is rapid in the apical zone compared to the rates in the more mature zones. (2) Nitrite reduction to amino level occurs rapidly in the roots of 20-day-old seedlings of the three plants at similar rates in the daytime and in the night. This reduction seems to be more rapid than the reduction of nitrate to amino level. (3) The nitrogen derived from fed nitrogen was transferred from the root to the leaf more actively in the daytime than in the night. This trend was true for both the nitrite-fed and nitrate-fed plants. However, nitrite does not seem to be transferred to the leaf, but some nitrate may be transferred in an unchanged form.