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Involvement of Nitric Oxide in γ-Aminobutyric Acid-Induced Cellular Mechanisms of Wheat Seedling Adaptation to Water Deficit - #γaminobutyricacid #nitricoxide #oxidativestress #antioxidantsystem #osmolytes #amylase #droughtresistance #Triticumaestivum #Triticum #wheat #waterdeficit #GABA - https://link.springer.com/article/10.3103/S0095452725060106

Involvement of Nitric Oxide in γ-Aminobutyric Acid-Induced Cellular Mechanisms of Wheat Seedling Adaptation to Water Deficit - Cytology and Genetics

Abstract γ-Aminobutyric acid (GABA) is one of the key stress metabolites involved in the functioning of the plant cell signaling network. However, its functional relationships with main signaling molecules, particularly nitric oxide (NO), are not well understood. This study aimed to determine NO’s involvement in GABA’s stress-protective effect on wheat seedlings (Triticum aestivum L., Etana cultivar) under model drought conditions (13% PEG 6000). Priming grains with a 0.5 mM GABA solution or a 0.1 mM solution of the NO donor sodium nitroprusside (SNP) increased germination energy, seed germination, and water content in seedlings under stressful conditions. Additionally, GABA and SNP treatment mitigated the inhibitory effect of drought on the accumulation of root and shoot biomass. Osmotic stress increased NO content in shoots, and priming with GABA and SNP enhanced this effect. Treatment with the nitric oxide scavenger methylene blue (MB, 0.1 mM) eliminated the increase in NO content caused by stress or GABA action. MB also negated the positive effects of GABA on growth processes. Under the action of GABA and SNP, total amylase activity in grains and soluble carbohydrate content in shoots increased under stressful conditions; MB eliminated GABA’s effect on these parameters. Under the model drought, the content of oxidative stress markers (superoxide anion radical, hydrogen peroxide, and malondialdehyde) increased in shoots, but pretreatment of grains with GABA or SNP significantly reduced these effects. Osmotic stress caused an increase in activity of catalase and guaiacol peroxidase in shoots. Preliminary priming with GABA, SNP, and MB did not affect the nature of the changes in activity of these antioxidant enzymes caused by model drought. Meanwhile, superoxide dismutase activity remained unchanged following exposure to the model drought; however, pretreatment seeds with GABA, SNP, and MB increased the enzyme activity. Priming seeds with GABA and SNP increased the total content of phenolic compounds in shoots and preserved the anthocyanin pool under stressful conditions, while MB treatment eliminated these effects. It was concluded that the enhancement of grain germination and seedling growth induced by GABA priming under model drought conditions is largely due to NO-mediated modulation of carbohydrate and secondary compound metabolism.

SpringerLink

Cytology and Genetics Oct 1, 2024

The Role of Reactive Oxygen Species and Calcium Ions in Implementing the Stress-Protective Effect of γ-Aminobutyric Acid on Wheat Seedlings Under Heat Stress Conditions - #Triticumaestivum #γaminobutyricacid #reactiveoxygenspecies #calcium #heatstress #oxidativedamage #antioxidantsystem #Triticum - https://link.springer.com/article/10.3103/S0095452724020063

The Role of Reactive Oxygen Species and Calcium Ions in Implementing the Stress-Protective Effect of γ-Aminobutyric Acid on Wheat Seedlings Under Heat Stress Conditions - Cytology and Genetics

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.

SpringerLink