Abstract
To evaluate the Ca-alleviating effect on sodium salt-induced phytotoxicity, wheat (Triticum aestivum L.) cultivar Xihan 3 seedlings were treated with 150 mM NaCl, CaCl(2) (0.1, 0.5, and 1 mM), Ca(2+)-channel blocker LaCl(3), and/or Ca(2+) 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(2+) and calmodulin (CaM) contents, and downregulated TaCaM expression in wheat leaves. The opposite changes of these parameters were caused by 0.5 or 1 mM CaCl(2) treatments alone. Moreover, 0.5 or 1 mM CaCl(2) application effectively alleviated sodium salt-induced changes of these parameters, which was blocked by LaCl(3) 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.