外源NO对铜胁迫下番茄光合、生物发光特性及矿质元素吸收的影响

采用营养液培养，研究了外源一氧化氮（NO）供体硝普钠(Sodium nitroprusside, SNP)对50 μmol/L铜（Cu）胁迫下番茄叶片叶绿素含量、光合特性、生物发光强度和矿质营养元素的影响。结果表明，在Cu胁迫下，外施100 μmol/L SNP显著提高番茄叶片叶绿素a、叶绿素b、叶绿素a+b含量、叶绿素a/b比值、净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和叶片中Cu、Ca、Fe、Zn、Mn以及根系中Cu、K、Fe、Zn的含量； 显著降低叶片超微弱发光强度、荧光强度、磷光强度、胞间CO2浓度(Ci)和根系中Ca的含量。然而，SNP对Cu胁迫下的缓解效应可被NO的清除剂血红蛋白所抑制。在Cu处理液中加入100 μmol/L NO-x（NO的分解产物）或100 μmol/L亚铁氰化钠（SNP的相似物或分解产物），与Cu胁迫处理差异不显著。表明外源NO可以通过改善Cu胁迫下番茄叶片光合特性，降低超微弱发光、荧光、磷光强度，维持矿质营养元素平衡，缓解Cu胁迫对番茄的抑制作用。

Effects of exogenous nitric oxide on photosynthetic,bioluminescent characteristics and mineral element contents in tomato under copper stress

Nitric oxide (NO) serves as a bioactive molecule involved in antioxidant and anti-stress agent in tolerance responses to abiotic stress. A hydroponic experiment was conducted to investigate the effects of exogenous sodium nitroprusside (SNP), a NO donor, on photosynthetic characteristics, bioluminescence intensity, chlorophyll and mineral element contents in tomato (Lycopersicon esculentum Mill.) plants treated with 50 µmol/L CuCl₂. The application of 100 µmol/L SNP significantly increased chlorophyll contents, net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), copper(Cu), calcium (Ca), iron (Fe), zinc (Zn), manganese (Mn) contents in leaves and copper(Cu), potassium (K), iron (Fe), zinc (Zn) contents in roots; and dramatically decreased ultraweak luminescence intensity, fluorescence intensity, phosphorescence intensity and calcium (Ca) content in roots induced by CuCl₂. While the mitigate response of SNP to Cu stress were inhibited by addition of hemoglobin (a NO scavenger). No significant difference on photosynthetic, bioluminescent characteristics and mineral element contents in tomato was observed by the application of sodium nitrate or nitrite (the decomposition products of NO or its donor SNP) or sodium ferrocyanide (an analog of SNP) which did not release NO. We concluded that exogenous NO could improve photosynthetic characteristics, decrease ultraweak luminescence intensity, fluorescence intensity, phosphorescence intensity, maintain the mineral nutrition balance, alleviate the inhibition of tomato by copper stress.