Function of the shoot base of salt-tolerant reed (Phragmites communisTrinius) plants for Na+exclusion from the shoots

Abstract
The function of the basal part of the shoot for salt tolerance of reed (Phragmites communis Trinius) was studied by 22Na+ uptake and histochemical experiments. Shoot-base girdling (3 s with hot air) increased the Na+ transport to shoot to 284% in 60 min and decreased the retranslocation of shoot Na+ to root to 24% in 30 min. These results suggest that Na+ exclusion from the shoot depends on the biological activity of the shoot base. Histochemical examination revealed that a high activity of vanadate-sensitive ATPase could be detected in the phloem region of the shoot base. This activity was completely inhibited by the hot girdling, suggesting that the phloem ATPase may be involved in the downward Na+ transport occurring in the shoot base of reed plants.