Exogenous calcium-alleviating effect on sodium salt-induced phytotoxicity associated with changes in photosynthetic characteristics of wheat seedlings.

To evaluate the Ca-alleviating effect on sodium salt-induced phytotoxicity, wheat ( L.) cultivar Xihan 3 seedlings were treated with 150 mM NaCl, CaCl (0.1, 0.5, and 1 mM), Ca-channel blocker LaCl, and/or Ca chelator, ethylene glycol tetraacetic acid (EGTA) alone or in combination, to investigate seedling growth and photosynthetic characteristics. NaCl (150 mM) exposure alone suppressed a growth of seedling, weakened photosynthetic efficiency and chlorophyll (Chl) fluorescence parameters, reduced photosynthetic pigments, Ca and calmodulin (CaM) contents, and downregulated expression in wheat leaves. The opposite changes of these parameters were caused by 0.5 or 1 mM CaCl treatments alone. Moreover, 0.5 or 1 mM CaCl application effectively alleviated sodium salt-induced changes of these parameters, which was blocked by LaCl or EGTA. Therefore, exogenous Ca presence effectively promoted the growth of NaCl-stressed wheat seedlings through the enhancement of photosynthesis and Chl synthesis mediated by the Ca-CaM signal.