外源一氧化氮对渗透胁迫下黑麦草幼苗光合和生物发光特性的影响

为了探讨一氧化氮(NO)对渗透胁迫下牧草光合生理响应的调节作用,采用水培方法,研究了外源NO供体硝普钠(SNP)对15% PEG 6000(-0.5 MPa)渗透胁迫下黑麦草幼苗叶片光合色素含量、气体交换参数、叶绿素荧光和生物发光强度的影响。结果表明,在渗透胁迫下,外施100 μmol/L SNP显著提高了黑麦草叶片中光合色素含量、净光合速率(P_n)、气孔导度(G_s)、蒸腾速率(T_r)、气孔限制值(L_s)、PSⅡ最大光化学效率(F_v/F_m)和实际光化学效率(Φ_PSⅡ),明显降低了胞间CO₂浓度(C_i)、PSⅡ激发压(1-q^P) 和非光化学猝灭(NPQ)及超弱发光强度、荧光强度和磷光强度。但SNP的这种效应可被NO的清除剂血红蛋白(Hb)所逆转。而100 μmol/L的 NO_x^-(NO的分解产物)或Na₃Fe(CN)₆ (SNP的相似物或分解产物)对渗透胁迫无显著改善。表明NO可能通过提高光合色素含量和光能利用率,降低生物发光强度,缓解渗透胁迫对黑麦草光合机构的破坏和光合速率的抑制。

Effects of exogenous nitric oxide on photosynthetic and bioluminescent characteristics in ryegrass seedlings under osmotic stress

The regulating effect of nitric oxide (NO) on photosynthetic physiological response of herbage under osmotic stress, was studied in a hydroponic experiment. The effect of the exogenous NO donor sodium nitroprusside (SNP) on the photosynthetic pigment content, gas exchange and chlorophyll fluorescence parameters, and bioluminescence intensity in leaves of ryegrass (Lolium perenne) under osmotic stress simulated by 15% PEG-6000 were investigated. The stress from 100 μmol/L SNP significantly increased photosynthetic pigment contents, net photosynthetic rate (P_n), stomatal conductance (G_s), transpiration rate (T_r), stomatal limited value (L_s), PSⅡ maximal photochemical efficiency (F_v/F_m) and actual photochemical efficiency (Φ_PSⅡ), but reduced intercellular CO₂ concentration (C_i), PSⅡ excitation pressure (1-q^P), non-photochemical quenching (NPQ), ultra-weak luminescence intensity, fluorescence intensity and phosphorescence intensity in ryegrass seedling leaves. The addition of haemoglobin (Hb), a NO scavenger, reversed the effects of SNP, but application of 100 μmol/L sodium nitrate or nitrite (the decomposition products of NO or its donor SNP) or sodium ferricyanide (an analog of SNP) had no significant alleviation effects on osmotic stress. NO may alleviate the damage of osmotic stress to the leaf photosynthetic apparatus by increasing photosynthetic pigment and light-energy utilization, and decreasing bioluminescent intensity, thus improving photosynthetic efficiency of the ryegrass seedlings under osmotic stress.