一氧化氮信号途径参与草地早熟禾耐镉机制的研究

为探究信号分子一氧化氮（Nitric Oxide，NO）对镉（Cadmium，Cd）胁迫下草地早熟禾（Poa pratensis）的调控机理，揭示草地早熟禾耐镉机理，本试验采取根施1000 μmol·L^-1氯化镉（Cadmium chloride hemidihydrate，CdCl₂·2.5H₂O）及叶面喷施NO合成酶抑制剂（L-硝基精氨酸甲酯（L-NAME））、硝酸还原酶抑制剂（钨酸钠（Tungstate））、NO清除剂（4-羧基苯-4，4，5，5-四甲基咪唑-1-氧-3-氧化物（cPTIO））处理草地早熟禾叶片，研究不同处理对草地早熟禾幼苗叶片生长及抗氧化酶活性、光合色素含量、丙二醛（Malondialdehyde，MDA）、游离脯氨酸、内源NO含量的影响。研究发现，镉胁迫下草地早熟禾内源NO含量增加，添加一氧化氮清除剂、一氧化氮合酶抑制剂、硝酸还原酶抑制剂可增加超氧化物歧化酶（Superoxide Dismutase，SOD）、过氧化氢酶（Catalase，CAT）、抗坏血酸过氧化物酶（Ascorbate peroxidase，APX）活性，降低过氧化物酶（Peroxidase，POD）活性，增加叶绿素a、叶绿素b、类胡萝卜素、丙二醛含量，降低脯氨酸（Proline，Pro）含量、叶片相对含水量（Relative Water Content，RWC）和干物质量（Dry matter content）。结果表明，一氧化氮合酶途径可能是早熟禾合成NO的主要途径，内源NO可通过调节抗氧化酶活性、光合色素含量、游离脯氨酸含量等途径缓解镉胁迫。

Study on Cadmium-resistant Mechanism of Poa pratensis Mediated by NO Signaling Pathway

The objective of this study is to investigate the regulation mechanism and pathway of endogenous NO in Kentucky bluegrass seedlings under cadmium stress. In this study,seedlings of Kentucky bluegrass under Cd stress (applying 1000 μmol·L^-1 CdCl₂·2.5H₂O to roots) were treated with nitric oxide synthase inhibitor,nitrate reductase inhibitor and nitric oxide scavenger for foliar spraying. The impacts of different treatments on leaf growth,the activity of antioxidase,photosynthetic pigment content,the malondialdehyde (MDA) content,the free proline (Pro) content and the endogenous NO content in leaves of Kentucky bluegrass were studied. The results showed that endogenous NO content was induced by cadmium stress in seedling leaves of Kentucky bluegrass. When applied with nitric oxide scavenger,nitric oxide synthase inhibitor and nitrate reductase inhibitor respectively,the activities of superoxide dismutase,catalase and ascorbate peroxidase were enhanced,while the activity of Peroxidase (POD) was inhibited;the content of chlorophyll a,chlorophyll b,carotenoids and malondialdehyde was significantly increased,while the free proline content,relative water content,dry matter content were declined. The results indicated that the nitric oxide synthase pathway may be the main pathway of NO synthesis in Kentucky bluegrass,and endogenous NO can alleviate cadmium stress by regulating antioxidant enzyme activity,photosynthetic pigment content and free proline content.