State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
J Environ Sci (China). 2012;24(5):940-8. doi: 10.1016/s1001-0742(11)60978-9.
The effect of calcium chloride (CaCl2) on rice seedling growth under cadmium chloride (CdCl2) stress, as well as the possible role of endogenous nitric oxide (NO) in this process, was studied. The growth of rice seedlings was seriously inhibited by CdCl2, and the inhibition was significantly mitigated by CaCl2. However, hemoglobin (Hb) and 2-(4-carboxyphenyl)-4, 4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) weakened the promotion effect of CaCl2. The results of NO fluorescence localization suggest that growth accelerated by CaCl2 might be associated with elevated NO levels. The content of Cd, protein thiols (PBT), and nonprotein thiols (NPT) in cell walls, cell organelles, and soluble fractions, respectively, of rice seedlings decreased considerably in the presence of CaCl2, whereas the content of pectin, hemicellulose 1 (HC1), and hemicellulose 2 (HC2) increased significantly. Elimination of endogenous NO in Cd+Ca treatment could promote the transportation of Cd2+ to cell organelles and soluble fractions and increase the content of NPT and PBT in leaves. In addition, transportation of Cd2+ to cell organelles and soluble fractions was retarded in roots, the content of NPT increased, and the content of PBT decreased. With elimination of endogenous NO in Cd+Ca treatment, the content of pectin, HC1, and HC2 decreased significantly. Thus, Ca may alleviate Cd toxicity via endogenous NO with variation in the levels of NPT, PBT, and matrix polysaccharides.
研究了氯化钙（CaCl2）在氯化镉（CdCl2）胁迫下对水稻幼苗生长的影响，以及内源性一氧化氮（NO）在此过程中可能发挥的作用。CdCl2 严重抑制了水稻幼苗的生长，而 CaCl2 则显著减轻了这种抑制作用。然而，血红蛋白（Hb）和 2-（4-羧基苯基）-4,4,5,5-四甲基咪唑啉-1-氧-3-氧化物（cPTIO）削弱了 CaCl2 的促进作用。NO 荧光定位的结果表明，CaCl2 促进的生长可能与 NO 水平的升高有关。在 CaCl2 的存在下，水稻幼苗细胞壁、细胞器和可溶部分中 Cd、蛋白巯基（PBT）和非蛋白巯基（NPT）的含量分别显著下降，而果胶、半纤维素 1（HC1）和半纤维素 2（HC2）的含量显著增加。在 Cd+Ca 处理中消除内源性 NO 可以促进 Cd2+向细胞器和可溶部分的运输，并增加叶片中 NPT 和 PBT 的含量。此外，Cd2+向细胞器和可溶部分的运输在根部受到阻碍，NPT 的含量增加，而 PBT 的含量减少。在 Cd+Ca 处理中消除内源性 NO 时，果胶、HC1 和 HC2 的含量显著下降。因此，Ca 可能通过内源性 NO 缓解 Cd 毒性，导致 NPT、PBT 和基质多糖水平发生变化。
