Plant Molecular Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
Plant Mol Biol. 2013 May;82(1-2):1-22. doi: 10.1007/s11103-013-0031-6. Epub 2013 Feb 28.
The exact mechanism of helicase-mediated salinity tolerance is not yet understood. We have isolated a DESD-box containing cDNA from Pisum sativum (Pea) and named it as PDH45. It is a unique member of DEAD-box helicase family; containing DESD instead of DEAD/H. PDH45 overexpression driven by constitutive cauliflower mosaic virus-35S promoter in rice transgenic [Oryza sativa L. cv. Pusa Basmati 1 (PB1)] plants confers salinity tolerance by improving the photosynthesis and antioxidant machinery. The Na(+) ion concentration and oxidative stress parameters in leaves of the NaCl (0, 100 or 200 mM) treated PDH45 overexpressing T1 transgenic lines were lower as compared to wild type (WT) rice plants under similar conditions. The 200 mM NaCl significantly reduced the leaf area, plant dry mass, net photosynthetic rate (PN), stomatal conductance (gs), intercellular CO2 (Ci), chlorophyll (Chl) content in WT plants as compared to the transgenics. The T1 transgenics exhibited higher glutathione (GSH) and ascorbate (AsA) contents under salinity stress. The activities of antioxidant enzymes viz. superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (GPX) and glutathione reductase (GR) were significantly higher in transgenics; suggesting the existence of an efficient antioxidant defence system to cope with salinity induced-oxidative damage. Yeast two-hybrid assay indicated that the PDH45 protein interacts with Cu/Zn SOD, adenosine-5'-phosphosulfate-kinase, cysteine proteinase and eIF(4G), thus confirming the involvement of ROS scavenging machinery in the transgenic plants to provide salt tolerance. Furthermore, the T2 transgenics were also able to grow, flower, and set viable seeds under continuous salinity stress of 200 mM NaCl. This study provides insights into the mechanism of PDH45 mediated salinity stress tolerance by controlling the generation of stress induced reactive oxygen species (ROS) and also by protecting the photosynthetic machinery through a strengthened antioxidant system.
螺旋酶介导耐盐性的确切机制尚不清楚。我们从豌豆（Pea）中分离出一个含 DESD 框的 cDNA，并将其命名为 PDH45。它是 DEAD-box 螺旋酶家族的独特成员；含有 DESD 而不是 DEAD/H。PDH45 在水稻转基因[Oryza sativa L. cv. Pusa Basmati 1 (PB1)]植株中由组成型花椰菜花叶病毒 35S 启动子驱动过表达，通过改善光合作用和抗氧化机制来赋予耐盐性。在相同条件下，与野生型（WT）水稻植株相比，用 NaCl（0、100 或 200 mM）处理的 PDH45 过表达 T1 转基因系叶片中的 Na+离子浓度和氧化应激参数较低。与转基因植物相比，200 mM NaCl 显著降低了 WT 植物的叶片面积、植物干重、净光合速率（PN）、气孔导度（gs）、胞间 CO2（Ci）、叶绿素（Chl）含量。在盐胁迫下，T1 转基因植物的谷胱甘肽（GSH）和抗坏血酸（AsA）含量较高。抗氧化酶活性，如超氧化物歧化酶（SOD）、抗坏血酸过氧化物酶（APX）、愈创木酚过氧化物酶（GPX）和谷胱甘肽还原酶（GR）在转基因植物中显著升高；表明存在有效的抗氧化防御系统来应对盐诱导的氧化损伤。酵母双杂交分析表明，PDH45 蛋白与 Cu/Zn SOD、腺苷-5'-磷酸硫酸激酶、半胱氨酸蛋白酶和 eIF(4G)相互作用，从而证实 ROS 清除机制参与了转基因植物以提供耐盐性。此外，T2 转基因植物也能够在持续 200 mM NaCl 盐胁迫下生长、开花和产生有活力的种子。这项研究深入了解了 PDH45 介导的耐盐性的机制，通过控制应激诱导的活性氧（ROS）的产生，以及通过强化抗氧化系统来保护光合作用机制。
