Abstract: The ultrasturctural location of adenosine triphosphatase (ATPase) active reaction in leaflet cells of rice seedlings were conducted by cytochemical method of lead phosphates deposition. The changes of ATPase activity in cells and the protective effect against chilling injury of exogehous cholesterol on the ATPase activity in leaflet cells of seedlings were studied. The results showed: 1. The ATPase activity in leaflet cells of rice seedlings grown at 28 ℃ was located at plasmolemma, plasmodesma, intercellular space, nuclear chromatin and chloroplastid lamella, but it was low at plasmolemma: 2. In the control, the ATPase activity at plasmolemma in leaflet cells incubated at 5 ℃ was inactivated, and decreased in chromatin and intercellular space, wheras it remained higher at chloroplast. In the leaflet cells treated with cholesterol, the ATPase activity at blasmolemma, plasmodesma and chloroplast remained higher when they were incubated at 5 ℃, and decreased in intercellular space and chromatin. 3. During 24–48 h of chilling injury, the ATPase activity in leaflet cells was almost inactivated at plasmolemma and chloroplastid lamella, and evidently decreased in chromatin and intercellular space in the control. There was not any change in the ATPase activity of the leaflet cells treated with cholesterol.

Key words: ATPase activity: Chilling injury: Cholesterol: Rice