Abstract:

Dynamic changes of Ca²⁺ in the mesophyll cells of outdoor Euonymus japonicus cv. ‘CuZhi’ under low temperature stress were investigated with a calcium antimonate precipitate-electromicroscopic-cytochemical method. Results showed that in the beginning the calcium particles in the mesophyll cell, from November 2010 to January 2011, mainly resided in intercellular spaces and vacuoles with a small number of calcium particles in the cytoplasm compared with those in summer conditions. Starch grains disappeared in most of the chloroplasts while more osmilphilic granules appeared. After then the number of calcium particles in intercellular spaces and vacuoles gradually decreased, whereas the particles in the cytoplasm significantly increased. Simultaneously, part of chloroplast membrane vesicled and began disintegration, more mitochondria emerged, and the central vacuole was divided into small vacuoles. Thus it could be concluded that there is a certain correlation between the changes of calcium distribution and concentration and the changes of the cell ultrastructure under low temperature stress.

Key words: Euonymus japonicus cv. &lsquo, CuZhi&rsquo, low temperature stress, Ca²⁺, mesophyll cell