Ultrastructural localization of ATPase in mature tracheary elements of rice (Oryza sativa L.) stamen.

The development of mature tracheary elements (TEs) of rice (Oryza sativa L. cv. Nongkeng 58s-SD) stamen from big-vacuole to trinucleate pollen stage was studied with lead phosphate--deposition technique. At big-vacuole pollen stage, mature TEs, both in filament and connective, were short of ATPase activity. However, ATPase activity appeared at binucleate pollen stage; in filament, one or two vascular bundle cell (s) next to TE degenerated earlier than the rest; and the plasma membrane of degenerating cell (DC) always exhibited high ATPase activity on condition that the adjoining TE was of fully stretched second wall; when the second wall only turned up far off DC, the plasma membrane of DC still showed high ATPase activity except on borderline between DC and TE; in connective at the same stage, TEs also exhibited high ATPase activity, but the vascular bundle cell(s) adjoining TEs degenerated much later than their counterparts in filament. At trinucleate pollen stage, materials, either with or without ATPase activity, were observed both in filament and connective TEs. The above results indicated that (some of the) materials in mature TEs come from filament DC.