Liu Shiliang, Yang Rongjie, Pan Yuanzhi, Ma Mingdong, Pan Jiang, Zhao Yan, Cheng Qingsu, Wu Mengxi, Wang Maohua, Zhang Lin
College of Landscape Architecture and Ornamental Horticulture, Sichuan Agricultural University, Chengdu 611130, PR China.
College of Landscape Architecture and Ornamental Horticulture, Sichuan Agricultural University, Chengdu 611130, PR China.
Ecotoxicol Environ Saf. 2015 Sep;119:35-46. doi: 10.1016/j.ecoenv.2015.04.053. Epub 2015 May 14.
Nitric oxide (NO) is a stress-signaling molecule in plants that mediates a wide range of physiological processes and responses to metal toxicity. In this work, various NO modulators (NO donor: SNP; NO scavenger: cPTIO; NO synthase inhibitor: l-NAME; and SNP analogs: sodium nitrite/nitrate and sodium ferrocyanide) were investigated to determine the role of NO in Trifolium repens L. plants exposed to Cd. Cd (100μM) markedly reduced biomass, NO production and chlorophyll (Chl a, Chl b and total Chl) concentration but stimulated reactive oxygen species (ROS) and Cd accumulation in plants. SNP (50μM) substantially attenuated growth inhibition, reduced hydrogen peroxide (H2O2) and malonyldialdehyde (MDA) levels, stimulated ROS-scavenging enzymes/agents, and mitigated the H(+)-ATPase inhibition in proton pumps. Interestingly, SNP considerably up-regulated the levels of jasmonic acid (JA) and proline in plant tissues but down-regulated the levels of ethylene (ET) in both shoots and roots and the level of salicylic acid (SA) in roots only, which might be related to the elevated NO synthesis. Additionally, SNP (25-200μM) regulated mineral absorption and, particularly at 50μM, significantly enhanced the uptake of shoot magnesium (Mg) and copper (Cu) and of root calcium (Ca), Mg and iron (Fe). Nevertheless, the effects of SNP on plant growth were reversed by cPTIO and l-NAME, suggesting that the protective effect of SNP might be associated with NO synthesis in vivo. Moreover, SNP analogs did not display roles similar to that of SNP. These results indicated that NO depleted Cd toxicity by eliminating oxidative damage, enhancing minerals absorption, regulating proton pumps, and maintaining hormone equilibrium.
一氧化氮（NO）是植物中的一种应激信号分子，介导多种生理过程以及对金属毒性的响应。在本研究中，研究了各种NO调节剂（NO供体：SNP；NO清除剂：cPTIO；NO合酶抑制剂：L-NAME；以及SNP类似物：亚硝酸钠/硝酸盐和亚铁氰化钠），以确定NO在白三叶草暴露于镉时所起的作用。镉（100μM）显著降低了生物量、NO生成量以及叶绿素（叶绿素a、叶绿素b和总叶绿素）浓度，但刺激了植物体内活性氧（ROS）的生成和镉的积累。SNP（50μM）显著减轻了生长抑制，降低了过氧化氢（H2O2）和丙二醛（MDA）水平，刺激了ROS清除酶/剂，并减轻了质子泵中H(+)-ATP酶的抑制作用。有趣的是，SNP显著上调了植物组织中茉莉酸（JA）和脯氨酸的水平，但仅下调了地上部和根部乙烯（ET）的水平以及根部水杨酸（SA）的水平，这可能与NO合成增加有关。此外，SNP（25 - 200μM）调节了矿物质吸收，特别是在50μM时，显著提高了地上部镁（Mg）和铜（Cu）以及根部钙（Ca）、镁和铁（Fe）的吸收。然而，cPTIO和L-NAME逆转了SNP对植物生长的影响，表明SNP的保护作用可能与体内NO合成有关。此外，SNP类似物未表现出与SNP类似的作用。这些结果表明，NO通过消除氧化损伤、增强矿物质吸收、调节质子泵以及维持激素平衡来减轻镉毒性。
