铜、镉毒害对番茄生长和膜功能蛋白酶活性的影响及外源NO的缓解效应

为探讨外源NO（SNP为供体）对50 mol/L铜、镉毒害的缓解效应，采用营养液培养方法，研究了不同程度的铜、镉毒害（5 mol/L和50 mol/L）对番茄幼苗生物量、根系活力、硝酸还原酶、光合特性及生物膜ATPase、H+-PPase等功能蛋白酶活性的影响。结果表明，铜、镉胁迫显著抑制番茄生长。随处理浓度增加，番茄根系活力、硝酸还原酶活性显著降低，番茄长势越差; 铜、镉胁迫对根系离子吸收的影响远远大于叶片，尤其是铜胁迫，50 mol/L铜胁迫使番茄根系铜含量增加了12倍。铜浓度的增加对镉含量无影响，镉浓度的增加降低了铜的吸收。铜、镉胁迫使番茄净光合速率（Pn）、气孔导度（Gs）和蒸腾速率（Tr）显著降低，胞间CO2浓度（Ci）显著增加，表现为非气孔限制。50 mol/L 铜、镉处理显著降低叶片、根系质膜H+-ATPase、Ca2+-ATPase和根系液泡膜H+-ATPase、Ca2+-ATPase和H+-PPase活性; 提高了5和50 mol/L部分处理叶片液泡膜H+-ATPase、Ca2+-ATPase和H+-PPase的活性。表明生物膜功能蛋白对不同程度铜、镉胁迫的响应时间和部位存在差异。铜毒害对细胞质膜ATPase的影响较大，而镉毒害对液泡膜伤害的程度较大。100 mol/L SNP可以显著缓解铜、镉胁迫导致的番茄生长受抑，铜、镉总吸收量显著高于胁迫处理。

Responses of growth, functional enzyme activity in biomembrane of tomato seedlings to excessive copper, cadmium and the alleviating effect of exogenous nitric oxide

We investigated the effects of the toxicity of copper, cadmium (5 µmol/L and 50 µmol/L) on tomato seedlings growth and physiological and biochemical characteristics using nutrient solution culture in greenhouse in this study. The testing indexes included copper and cadmium content, root activity, nitrate reductase activity, photosynthetic characteristics, ATPase and H⁺-PPase activity in biomembrane. The alleviating effect of exogenous nitric oxide under copper, cadmium stress was also discussed preliminarily. The results showed that copper, cadmium stress significantly restrained tomato growth. With the increase of stress degree, root activity and nitrate reductase activity declined dramatically, and the appearance of plant turned into worse. The copper, cadmium stress had a more severe effect on ion adsorption in roots than in leaves, particularly for copper. Copper stress at 50 µmol/L increased copper content by 12 times in tomato roots, but had no effect on cadmium content. The cadmium stress reduced copper absorption. The copper, cadmium stress dramatically decreased net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs), while enhanced the intercellular CO₂ concentration (Ci). The copper, cadmium stress (50 µmol/L) also remarkably depressed the activities of H⁺-ATPase、Ca²⁺-ATPase in plasma membrane of leaves and roots, and the activities of H⁺-ATPase、Ca²⁺-ATPase and H⁺-PPase in root tonoplast membrane, indicating the response time and location of function protein of biological membrane to copper and cadmium stress varied with stress levels. Copper toxicity damaged more on the plasma membrane, while cadmium toxicity injured more on tonoplast membrane. Addition of 100 µmol/L SNP (a NO donor) could significantly alleviate the inhibitory effects induced by excessive copper, cadmium, and increased the total absorption of copper and cadmium.