Salt stress limits crop productivity worldwide, particularly in arid and heavily irrigated regions. Salt stress causes oxidative stress, in which plant cells accumulate harmful levels of reactive oxygen species (ROS). Thioredoxins (Trxs; EC 1.8.4.8) are antioxidant proteins encoded by a ubiquitous multigene family. Arabidopsis thaliana Trx h-type proteins localize in the cytoplasm and other subcellular organelles, and function in plant responses to abiotic stresses and pathogen attack. Here, we isolated the Arabidopsis genes encoding two cytosolic h-type Trx proteins, AtTrx-h2 and AtTrx-h3 and generated transgenic oilseed rape (Brassica napus) plants overexpressing AtTrx-h2 or AtTrx-h3. Heterologous expression of AtTrx-h2 in B. napus conferred salt tolerance with plants grown on 50 mM NaCl having higher fresh weight and chlorophyll contents compared with controls in hydroponic growth system. By contrast, expression of AtTrx-h3 or the empty vector control did not improve salt tolerance. In addition, AtTrx-h2-overexpressing transgenic plants exhibited lower levels of hydrogen peroxide and higher activities of antioxidant enzymes including peroxidase, catalase, and superoxide dismutase, compared with the plants expressing the empty vector control or AtTrx-h3. These results suggest that AtTrx-h2 is a promising candidate for engineering or breeding crops with enhanced salt stress tolerance.

中文翻译：

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甘蓝型油菜中拟南芥硫氧还蛋白-h2的表达增强了抗氧化防御能力，并提高了耐盐性。

盐胁迫限制了全世界的作物生产力，特别是在干旱和严重灌溉的地区。盐胁迫导致氧化胁迫，其中植物细胞积累有害水平的活性氧（ROS）。硫氧还蛋白（Trxs; EC 1.8.4.8）是由无处不在的多基因家族编码的抗氧化剂蛋白。拟南芥Trx h型蛋白位于细胞质和其他亚细胞器中，并在植物对非生物胁迫和病原体侵袭的反应中起作用。在这里，我们分离了编码两种胞质h型Trx蛋白AtTrx-h2和AtTrx-h3的拟南芥基因，并生成了过表达AtTrx-h2或AtTrx-h3的转基因油菜（甘蓝型油菜）植物。AtTrx-h2在B中的异源表达 与水培生长系统中的对照相比，甘蓝型油菜对在50 mM NaCl上生长的植物具有更高的鲜重和叶绿素含量，从而提高了耐盐性。相比之下，AtTrx-h3的表达或空载体对照不能提高耐盐性。另外，与表达空载体对照或AtTrx-h3的植物相比，过表达AtTrx-h2的转基因植物表现出较低水平的过氧化氢和较高的抗氧化剂酶活性，包括过氧化物酶，过氧化氢酶和超氧化物歧化酶。这些结果表明，AtTrx-h2是具有增强的盐胁迫耐受性的工程或育种作物的有前途的候选者。与表达空载体对照或AtTrx-h3的植物相比，过表达AtTrx-h2的转基因植物显示出较低水平的过氧化氢和较高的抗氧化剂酶活性，包括过氧化物酶，过氧化氢酶和超氧化物歧化酶。这些结果表明，AtTrx-h2是具有增强的盐胁迫耐受性的工程或育种作物的有前途的候选者。与表达空载体对照或AtTrx-h3的植物相比，过表达AtTrx-h2的转基因植物显示出较低的过氧化氢水平和较高的抗氧化剂酶活性，包括过氧化物酶，过氧化氢酶和超氧化物歧化酶。这些结果表明，AtTrx-h2是具有增强的盐胁迫耐受性的工程或育种作物的有前途的候选者。