Cytochemical localization of calcium and Ca2+-ATPase activity in plant cells under chilling stress: a comparative study between the chilling-sensitive maize and the chilling-insensitive winter wheat
1999
Jian, L. | Li, J. | Chen, W.P. | Li, P.H. | Ahlstrand, G.G.
Electron microscopic observations revealed that electron-dense antimonate Ca2+ deposits were mostly localized in the vacuole and the intercellular space in both maize and winter wheat when their seedlings were grown at 25 degrees C. The reaction products--cerium phosphate deposits of Ca2+ -ATPase activity were mainly seen at the cytoplasmic side of the plasma membrane. Few cerium phosphate deposits also were observed on the nuclear envelope. In both species, after 1 or 3 h 2 degrees C chilling, antimonate Ca2+ deposits increased in the cytosol and the nucleus, but cerium phosphate deposits showed no visible difference compared to their corresponding 25 degrees C seedlings. After 12, 24, or 72 h chilling, maize seedlings still maintained a high level of antimonate Ca2+ deposits in the cytosol and the nucleus. During these periods, maize Ca2+ -ATPase, as indicated by the number of cerium phosphate deposits, became less and less active as chilling proceeded. In winter wheat, the increased cytosolic and nuclear antimonate Ca2+ deposits were restored to a low resting level after 12, 24, or 72 h chilling, while the Ca2+ -ATPase was maintained active, contrary to maize scenario. The transient cytosolic and nuclear Ca2+ increase and the activities of Ca2+ -ATPase during chilling are discussed in relation to plant chilling injury and cold acclimation.
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