Abstract: The results obtained by the cytochemical localization of ATPase activity reaction indicate that tile high enzyme activity was exhibited at the plasmalemma and endoplasmic reticulum in sieve elements and companion cells, and observed in the ground cytoplasm, vesicles and vacuoles of some companion cells. The reaction products of ATPase activity were also found at the plasmalemma and in the vesicles of parenchymatous, sclerenchymatous and mestom cells, and shown in intercellular spaces between the bundle sheath cells and the sclerenchyma cells or the mestom cells. The reaction strength of ATPase activity in different kinds of vascular bundles and its neighbouring mesophyll cells appeared to be not consistent. The activity at the free surfaces of mesophytl cells around large vein is higher than that of middle vein, and that of small vein is the lowest. Contrarily, the ATPase activity at the plasmalemma in small vein sheath cells is higher than that of middle and large vien. The highest ATPase activity was localized at the plasmalemma of phloem cells. Very high ATPase activity was also found at the plasmodesmata between the bundle sheath cell and the mesophyll cell. The results suggest that the photosynthates may be moved from mesophyll cells into bundle sheath cells through the plasmodesmata, and exported to apoplast of phloem from chlorenchymatous bundle sheath cells, and then actively loaded into the sieve element-companion cell complex.

Key words: Sugarcane leaves, Localization of ATPase activity