Arsenic (As) being a toxic metalloid adversely affects plant growth and yield, as well as poses severe risks to human health. Hydrogen sulfide (H2S) has emerged a vital signaling molecule regulating key plant growth processes under stress conditions. However, till date little information is available regarding the role of H2S in mitigating As toxicity in pea plants. In the present study, the effect of externally applied H2S and its scavenger hypotaurine (HT) on various morphological, physiological and biochemical parameters of pea plants was evaluated. Our results showed significant decline in root length (RL), shoot length (SL), dry biomass, photosynthetic parameters such as pigment content and gas exchange characteristics in pea plants subjected to As stress. However, H2S supplementation significantly decreased As accumulation in the roots and shoot, as well as considerably enhanced growth and photosynthetic parameters. Hydrogen peroxide (H2O2), malondialdehyde (MDA) and electrolyte leakage (EL) increased significantly in the As-treated plants, while H2S supplementation considerably reduced the levels of H2O2 and MDA as well as EL. Arsenic stress accelerated the activities of antioxidant and AsA-GSH cycle enzymes except that of CAT; however, the activities of these enzymes were found to be further increased by H2S supply including that of CAT. Furthermore, ascorbate (AsA), glutathione (GSH) and methylglyoxal (MG) levels were significantly enhanced by As stress, and were further intensified in the H2S-supplemented plants. Our results demonstrated significant role of H2S in reducing As accumulation and inducing upregulation of the AsA-GSH cycle to overcome ROS-mediated oxidative damage to the cellular components of pea plants. Hence, H2S reduced oxidative damage and promoted growth of pea plants under As stress, suggesting an important role of H2S in plant priming.

中文翻译：

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硫化氢 (H2S) 通过调节渗透调节、抗氧化防御系统、抗坏血酸谷胱甘肽循环和乙二醛酶系统减轻豌豆 (Pisum sativum L.) 植物中砷 (As) 诱导的毒性

砷 (As) 是一种有毒的准金属，会对植物生长和产量产生不利影响，并对人类健康构成严重威胁。硫化氢 (H2S) 已成为一种重要的信号分子，在胁迫条件下调节关键植物生长过程。然而，迄今为止，关于 H2S 在减轻豌豆植物中砷毒性方面的作用的信息很少。在本研究中，评估了外施 H2S 及其清除剂亚牛磺酸 (HT) 对豌豆植物各种形态、生理和生化参数的影响。我们的结果表明，受到砷胁迫的豌豆植株的根长 (RL)、枝条长 (SL)、干生物量、光合参数（如色素含量和气体交换特性）均显着下降。然而，H2S 补充显着降低了根和芽中砷的积累，并显着提高了生长和光合参数。过氧化氢 (H2O2)、丙二醛 (MDA) 和电解液泄漏 (EL) 在 As 处理的植物中显着增加，而 H2S 补充显着降低了 H2O2 和 MDA 以及 EL 的水平。砷胁迫加速了除CAT外的抗氧化酶和AsA-GSH循环酶的活性；然而，发现这些酶的活性通过 H2S 供应进一步增加，包括 CAT 的供应。此外，As 胁迫显着提高了抗坏血酸 (AsA)、谷胱甘肽 (GSH) 和甲基乙二醛 (MG) 的水平，并在补充 H2S 的植物中进一步增强。我们的结果表明 H2S 在减少 As 积累和诱导 AsA-GSH 循环上调以克服 ROS 介导的豌豆植物细胞成分氧化损伤方面的重要作用。因此，硫化氢在砷胁迫下减少了氧化损伤并促进了豌豆植株的生长，表明硫化氢在植物启动中起重要作用。