外源一氧化氮对渗透胁迫下小麦幼苗叶片膜脂过氧化的缓解作用

采用15%的聚乙二醇-6000(PEG-6000)对扬麦158三叶一心期的幼苗根部进行轻度渗透胁迫处理,并通过添加不同浓度的一氧化氮(nitric oxide,NO)供体硝普钠(sodium nitropussidi,SNP)和相应的对照(BO-3/NO-2),研究外源NO处理对渗透胁迫下小麦幼苗叶片膜脂过氧化作用的影响.结果发现,0.1 nnol/L的SNP能降低渗透胁迫造成的小麦幼苗叶片脂氧合酶(lipoxygenase,LOX)活性的提高,降低超氧阴离子(O-2)的产生速率和质膜相对透性的增加以及丙二醛(MDA)和H2O2的累积;0.1 mmol/L的SNP还能够诱导超氧化物歧化酶(superoxide dismutase,SOD)活性,加速脯氨酸(Pro)的累积,而0.5mmo1/L的SNP和0.1mmo1/L的NO3/NO2(对照)处理的效果则不明显.上述结果表明低浓度NO对渗透胁迫造成的膜脂过氧化有明显的缓解效应.

Exogenous Nitric Oxide Alleviates Osmotic Stress-induced Membrane Lipid Peroxidation in Wheat Seedling Leaves

Abstract:When wheat (Triticum aestivum L. Yangmai 158) seedling (with three fully expanded leaves) roots were treated with 15% PEG-6000 in combination with different concentrations (0.1 and 0.5 mmol/L) of exogenous nitric oxide donor sodium nitroprusside (SNP) and NO3-/NO2- (control), the enhancement of lipoxygenase (LOX) activity in wheat seedling leaves under osmotic stress was delayed at the lower concentration of SNP treatment (0.1 mmol/L) (Fig.2), while the generation rate of O2-, the enhancement of membrane permeability and the accumulation of MDA and H2O2 were also alleviated (Figs. 1,3). SNP 0.1 mmol/L significantly enhanced the activity of superoxide dismutase (SOD)(Fig.4), and accelerated the accumulation of proline (Fig.5). In comparison with these changes, the effects of higher concentration of SNP (0.5 mmol/L) and corresponding control (NO3-/NO2-) were not so obvious (Figs. 1-5). The above results indicate that lower concentrations of in vitro nitric oxide (NO) can protect wheat seedling leaves from membrane lipid peroxidation caused by osmotic stress.