Sehar Zebus, Mir Iqbal R, Khan Sheen, Masood Asim, Khan Nafees A
Plant Physiology and Biochemistry Laboratory, Department of Botany, Aligarh Muslim University, Aligarh 202002, India.
Plants (Basel). 2023 Mar 10;12(6):1256. doi: 10.3390/plants12061256.
The effects of exogenously-sourced NO (nitric oxide, as 100 µM SNP) and proline (50 mM) in the protection of the photosynthetic performance of wheat ( L.) plants against heat stress were investigated. The study focused on the mechanisms of proline accumulation, activity, gene expression of antioxidant enzymes, and NO generation. Plants were exposed to a temperature of 40 °C for 6 h per day over 15 days, then allowed to recover at 28 °C. Heat-stressed plants showed increased oxidative stress, with higher levels of HO and TBARS (thiobarbituric acid reactive substances) and increased proline accumulation, ACS activity, ethylene evolution, and NO generation, which in turn leads to increased accumulation of antioxidant enzymes and reduced photosynthetic attributes. In the tested wheat cultivar, the exogenous application of SNP and proline under heat stress improved the photosynthesis and reduced oxidative stress by enhancing the enzymatic antioxidant defense system. Potentially, the promoter AOX (alternative oxidase) played a role in maintaining redox homeostasis by lowering HO and TBARS levels. The genes for GR antioxidant and photosystem II core protein encoding psbA and psbB were highly up-regulated in nitric oxide and proline treated heat-stressed plants, indicating that ethylene positively impacted photosynthesis under high temperature stress. Moreover, nitric oxide supplementation under high temperature stress optimized ethylene levels to regulate the assimilation and metabolism of proline and the antioxidant system, lowering the adverse effects. The study showed that nitric oxide and proline increased high temperature stress tolerance in wheat by increasing the osmolytes accumulation and the antioxidant system, resulting in enhanced photosynthesis.
研究了外源一氧化氮（NO，以100μM的硝普钠形式）和脯氨酸（50 mM）对小麦植株光合性能的保护作用，使其免受热胁迫影响。该研究聚焦于脯氨酸积累、抗氧化酶活性、基因表达以及NO生成的机制。将植株在15天内每天置于40°C温度下6小时，随后在28°C下恢复。热胁迫植株表现出氧化应激增加，过氧化氢（HO）和硫代巴比妥酸反应性物质（TBARS）水平升高，脯氨酸积累、ACS活性、乙烯释放和NO生成增加，进而导致抗氧化酶积累增加和光合特性降低。在受试小麦品种中，热胁迫下外源施用硝普钠和脯氨酸通过增强酶促抗氧化防御系统改善了光合作用并降低了氧化应激。潜在地，交替氧化酶（AOX）启动子通过降低HO和TBARS水平在维持氧化还原稳态中发挥了作用。在经一氧化氮和脯氨酸处理的热胁迫植株中，编码psbA和psbB的GR抗氧化剂和光系统II核心蛋白的基因高度上调，表明乙烯在高温胁迫下对光合作用产生了积极影响。此外，高温胁迫下补充一氧化氮优化了乙烯水平，以调节脯氨酸的同化和代谢以及抗氧化系统，降低了不利影响。该研究表明，一氧化氮和脯氨酸通过增加渗透溶质积累和抗氧化系统来提高小麦对高温胁迫的耐受性，从而增强光合作用。
