Large amount of N03 --N are accumulated in vacuole, and cannot be timeously reducted, reutilized and transported into cytoplasm. It is the main reason for great N03--N accumulation in vacuole and nitrogen (N) use efficiency cannot be further improved. Transport mechanism of N03--N across tonoplast is explained in this paper, there are two proton pumps (H+-ATPase and H+-PPase) on tonoplast with absolutely different biology functions and physical characteristic. Mg·ATP and Mg·PPi are the specific substrates of H+-ATPase and H+-PPase respectivel...
