Department of Biology, Faculty of Science, University of Tabuk, Tabuk 71491, Saudi Arabia.
Chair of Climate Change, Environmental Development and Vegetation Cover, Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia.
Int J Mol Sci. 2018 Dec 11;19(12):3981. doi: 10.3390/ijms19123981.
Hydrogen sulfide (H₂S) has emerged as an important signaling molecule and plays a significant role during different environmental stresses in plants. The present work was carried out to explore the potential role of H₂S in reversal of dehydration stress-inhibited -acetylserine (thiol) lyase (OAS-TL), l-cysteine desulfhydrase (LCD), and d-cysteine desulfhydrase (DCD) response in arugula ( Mill.) plants. Dehydration-stressed plants exhibited reduced water status and increased levels of hydrogen peroxide (H₂O₂) and superoxide (O₂) content that increased membrane permeability and lipid peroxidation, and caused a reduction in chlorophyll content. However, H₂S donor sodium hydrosulfide (NaHS), at the rate of 2 mM, substantially reduced oxidative stress (lower H₂O₂ and O₂) by upregulating activities of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase) and increasing accumulation of osmolytes viz. proline and glycine betaine (GB). All these, together, resulted in reduced membrane permeability, lipid peroxidation, water loss, and improved hydration level of plants. The beneficial role of H₂S in the tolerance of plants to dehydration stress was traced with H₂S-mediated activation of carbonic anhydrase activity and enzyme involved in the biosynthesis of cysteine (Cys), such as OAS-TL. H₂S-treated plants showed maximum Cys content. The exogenous application of H₂S also induced the activity of LCD and DCD enzymes that assisted the plants to synthesize more H₂S from accumulated Cys. Therefore, an adequate concentration of H₂S was maintained, that improved the efficiency of plants to mitigate dehydration stress-induced alterations. The central role of H₂S in the reversal of dehydration stress-induced damage was evident with the use of the H₂S scavenger, hypotaurine.
硫化氢（H₂S）已成为一种重要的信号分子，在植物应对不同环境胁迫时发挥着重要作用。本研究旨在探索 H₂S 在逆转脱水胁迫抑制的乙酰丝氨酸（硫醇）裂解酶（OAS-TL）、L-半胱氨酸脱硫酶（LCD）和 D-半胱氨酸脱硫酶（DCD）响应中的潜在作用在芝麻菜（Mill.）植物中。脱水胁迫下的植物表现出降低的水势和增加的过氧化氢（H₂O₂）和超氧阴离子（O₂）含量，这增加了膜通透性和脂质过氧化作用，并导致叶绿素含量降低。然而，H₂S 供体硫氢化钠（NaHS）以 2mM 的速率显著降低了氧化应激（较低的 H₂O₂和 O₂），方法是上调抗氧化酶（超氧化物歧化酶、过氧化物酶和过氧化氢酶）的活性并增加渗透物脯氨酸和甘氨酸甜菜碱（GB）的积累。所有这些共同导致了膜通透性、脂质过氧化、水分损失的减少，以及植物水合水平的提高。H₂S 通过激活碳酸酐酶活性和参与半胱氨酸（Cys）生物合成的酶（如 OAS-TL），介导对植物耐受脱水胁迫的有益作用。H₂S 处理的植物表现出最大的 Cys 含量。H₂S 的外源应用还诱导了 LCD 和 DCD 酶的活性，这些酶有助于植物从积累的 Cys 中合成更多的 H₂S。因此，维持了足够浓度的 H₂S，提高了植物缓解脱水胁迫诱导的变化的效率。使用 H₂S 清除剂硫代牛磺酸（Hypotaurine），H₂S 在逆转脱水胁迫诱导损伤中的核心作用显而易见。
