外源NO对盐胁迫下黑麦草幼苗根生长抑制和氧化损伤的缓解效应

研究了外源一氧化氮(nitric oxide, NO)对盐胁迫下黑麦草幼苗根生长和氧化损伤的影响。结果表明，5~100 μmol·L^-1的NO供体硝普钠(sodium nitroprusside, SNP)处理显著减轻100mmol·L^-1 NaCl胁迫对黑麦草幼苗根生长的抑制效应，其中50 μmol·L^-1的SNP效果最明显，150 μmol·L^-1以上的SNP处理则抑制根的生长。50 μmol·L^-1 SNP处理提高了100 mmol·L^-1 NaCl胁迫下黑麦草幼苗根组织中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)及液泡膜上H⁺-ATP酶(H⁺-ATPase)和H⁺焦磷酸酶(H⁺-PPase)的活性，使谷胱甘肽(GSH)、抗坏血酸(ASA)和脯氨酸含量及K⁺/Na⁺、(Spd+Spm)/Put比值和根干物质积累量增加，超氧阴离子(O^-₂)、H₂O₂和丙二醛(MDA)含量降低，而1mmol·L^-1NO清除剂PTIO和1 μmol·L^-1 NaNO₂处理(对照)的效果则不明显。由此推断，NO通过提高根组织的抗氧化和渗透调节能力，促进根系对K⁺的选择性吸收及Put向Spd和Spm的转化，降低Na⁺的吸收并加强在液泡中的区隔化缓解盐胁迫对黑麦草幼苗根生长的抑制和膜脂过氧化损伤。

Alleviative Effects of Exogenous Nitric Oxide on Root Growth Inhibition and Its Oxidative Damage in Rye Grass Seedlings Under NaCl Stress

Effects of exogenous nitric oxide (NO) on root growth and its oxidative damage in rye grass (Lolium perenne L. caddieshack) seedlings under NaCl stress were studied. The results showed that with its concentration at 5~100 μmol·L^-1 sodium nitroprusside(SNP), an NO donor, could significantly alleviate the inhibitory effect of seedlings root Growth under 100 mmol·L^-1 NaCl stress, and 50 μmol·L^-1 SNP was most effective, but inhibited the root growth at 150 μmol·L^-1 or higher. SNP at 50 μmol·L^-1 raised the activities of superoxide dismutase (SOD), catelase (CAT), peroxidase (POD) and ascorbate peroxidase (APX), tonoplast H⁺-ATPase and H⁺-PPase of root- tips of rye grass seedling under 100 mmol·L^-1 NaCl stress, increased the contents of glutathione (GSH), ascorbic acid (ASA) and proline, K⁺/Na⁺ and (Spd+Spm)/Put ratio, and dry matter accumulation, respectively, reduced the contents of O^-₂, H₂O₂ and malondiadehyde (MDA), while the effect wasn’t distinct when treated with 1 mmol·L^-1 NO scavenger(2-phenel-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, PTIO) and 1 mmol·L^-1 NaNO₂ (as control). The above results suggested that NO could attenuate the root growth inhibition and its oxidative damage caused by salt stress through increasing antixoidative and osmotic adjustment capabilities, accelerating the selective uptake of root to K⁺ and the transformation Put into Spd and Spm, and decreasing Na⁺ uptake and enhancing compartmentalization of Na⁺ in vacuole.