Department of Biology, College of Haql, University of Tabuk, Tabuk, 71491, Saudi Arabia.
Department of Botany and Microbiology, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia.
Environ Pollut. 2023 Oct 1;334:122008. doi: 10.1016/j.envpol.2023.122008. Epub 2023 Jun 23.
Crop plants face severe yield losses worldwide owing to their exposure to multiple abiotic stresses. The study described here, was conducted to comprehend the response of cucumber seedlings to drought (induced by 15% w/v polyethylene glycol 8000; PEG) and nickel (Ni) stress in presence or absence of titanium dioxide nanoparticle (nTiO). In addition, it was also investigated how nitrogen (N) and carbohydrate metabolism, as well as the defense system, are affected by endogenous potassium (K) and hydrogen sulfide (HS). Cucumber seedlings were subjected to Ni stress and drought, which led to oxidative stress and triggered the defense system. Under the stress, N and carbohydrate metabolism were differentially affected. Supplementation of the stressed seedlings with nTiO (15 mg L) enhanced the activity of antioxidant enzymes, ascorbate-glutathione (AsA-GSH) system and elevated N and carbohydrates metabolism. Application of nTiO also enhanced the accumulation of phytochelatins and activity of the enzymes of glyoxalase system that provided additional protection against the metal and toxic methylglyoxal. Osmotic stress brought on by PEG and Ni, was countered by the increase of proline and carbohydrates levels, which helped the seedlings keep their optimal level of hydration. Application nTiO improved the biosynthesis of HS and K retention through regulating Cys biosynthesis and H-ATPase activity, respectively. Observed outcomes lead to the conclusion that nTiO maintains redox homeostasis, and normal functioning of N and carbohydrates metabolism that resulted in the protection of cucumber seedlings against drought and Ni stress. Use of 20 mM tetraethylammonium chloride (K- channel blocker), 500 μM sodium orthovanadate (PM H-ATPase inhibitor), and 1 mM hypotaurine (HS scavenger) demonstrate that endogenous K and HS were crucial for the nTiO-induced modulation of plants' adaptive responses to the imposed stress.
作物因遭受多种非生物胁迫而导致全球产量严重损失。本研究旨在探究黄瓜幼苗对干旱（由 15%w/v 聚乙二醇 8000 诱导）和镍（Ni）胁迫的响应，以及在有无二氧化钛纳米颗粒（nTiO）存在的情况下的响应。此外，还研究了氮（N）和碳水化合物代谢以及防御系统如何受到内源性钾（K）和硫化氢（HS）的影响。黄瓜幼苗受到 Ni 胁迫和干旱的影响，导致氧化应激并触发防御系统。在胁迫下，N 和碳水化合物代谢受到不同程度的影响。向受胁迫的幼苗补充 nTiO（15mgL）可增强抗氧化酶、抗坏血酸-谷胱甘肽（AsA-GSH）系统的活性，提高 N 和碳水化合物代谢水平。nTiO 的应用还可增强植物螯合肽的积累和乙醛酸循环系统酶的活性，为金属和有毒的甲基乙二醛提供额外的保护。PEG 和 Ni 带来的渗透胁迫可通过脯氨酸和碳水化合物水平的增加得到缓解，这有助于幼苗保持最佳的水合状态。nTiO 的应用通过调节半胱氨酸生物合成和 H-ATPase 活性分别提高了 HS 的生物合成和 K 的保留。观察到的结果得出结论，nTiO 维持了氧化还原稳态以及 N 和碳水化合物代谢的正常功能，从而保护黄瓜幼苗免受干旱和 Ni 胁迫的影响。使用 20mM 四乙基氯化铵（K 通道阻断剂）、500μM 偏钒酸钠（PM H-ATPase 抑制剂）和 1mM 次牛磺酸（HS 清除剂）表明，内源性 K 和 HS 对 nTiO 诱导的植物适应胁迫的调节至关重要。
