γ-aminobutyric acid (GABA) is considered a molecule that combines the properties of a stress metabolite and a signaling molecule. At the same time, the importance of its functional interaction with other signaling mediators, in particular, reactive oxygen species (ROS) and calcium ions, for the implementation of stress-protective action on plant cells remains poorly researched. The authors studied the effect of GABA on the resistance of wheat seedlings (Triticum aestivum L., cultivar Doskonala) to potentially lethal heat stress and the participation of ROS and calcium in the manifestation of the effects of GABA. Treatment of seedlings with GABA in concentrations of 0.5 and 1 mM caused a significant increase in their survival after damaging heating in a water thermostat (10 min at 45°C). Under the influence of GABA, there was a transient increase in the content of hydrogen peroxide in the roots of seedlings, followed by an increase in the activity of antioxidant enzymes: superoxide dismutase, catalase, and guaiacol peroxidase. The specified effects of GABA were eliminated by the preliminary application of the hydrogen peroxide scavenger dimethylthiourea (DMTU) to the root incubation medium and were significantly suppressed in the presence of the NADPH oxidase inhibitor imidazole. At the same time, the treatment of seedlings with the chelator of extracellular calcium EGTA only partially eliminated the increase in the content of hydrogen peroxide and hardly affected the increase in the activity of antioxidant enzymes in the roots under the influence of GABA. Treatment with neomycin, an inhibitor of calcium uptake from intracellular compartments, caused a partial reduction in the effect of GABA on indicators of the state of the pro-/antioxidant system in wheat roots but did not eliminate these effects. Under the influence of GABA, damage to root cell membranes caused by heat stress was significantly reduced, which was manifested in a decrease in the release of UV-B-absorbing compounds from the cells and a decrease in the content of lipid peroxide oxidation products. At the same time, the stress-protective effect of GABA was eliminated by DMTU treatment and changed in the presence of calcium antagonists. A conclusion was made about the important role of ROS generated with the participation of NADPH oxidase in the implementation of the protective effect of GABA on wheat seedlings under conditions of heat stress and the partial dependence of its protective effects on calcium homeostasis.

γ-氨基丁酸 (GABA) 被认为是一种结合了应激代谢物和信号分子特性的分子。与此同时，其与其他信号传导介质（特别是活性氧（ROS）和钙离子）的功能相互作用对于对植物细胞实施应激保护作用的重要性仍然缺乏研究。作者研究了 GABA 对小麦幼苗（Triticum aestivum L.，品种 Doskonala）对潜在致命热应激的抵抗力的影响，以及活性氧和钙在 GABA 影响表现中的参与。用浓度为 0.5 和 1 mM 的 GABA 处理幼苗，在水恒温器中进行破坏性加热（45°C 10 分钟）后，幼苗的存活率显着增加。在GABA的影响下，幼苗根部的过氧化氢含量出现短暂增加，随后抗氧化酶：超氧化物歧化酶、过氧化氢酶和愈创木酚过氧化物酶的活性增加。通过将过氧化氢清除剂二甲基硫脲 (DMTU) 预先施用到根培养介质中，GABA 的特定作用被消除，并且在 NADPH 氧化酶抑制剂咪唑存在的情况下被显着抑制。同时，细胞外钙螯合剂EGTA处理幼苗仅部分消除了过氧化氢含量的增加，几乎不影响GABA影响下根部抗氧化酶活性的增加。新霉素（一种细胞内钙吸收抑制剂）处理导致 GABA 对小麦根部促氧化/抗氧化系统状态指标的影响部分降低，但并没有消除这些影响。在GABA的影响下，热应激对根细胞膜的损伤显着减轻，表现为细胞中吸收UV-B的化合物释放减少和脂质过氧化物氧化产物含量减少。同时，GABA 的应激保护作用被 DMTU 处理消除，并且在钙拮抗剂存在下发生变化。总结了NADPH氧化酶参与产生的ROS在热胁迫条件下GABA对小麦幼苗保护作用的实现中的重要作用以及其保护作用部分依赖于钙稳态。