Response of the Antioxidant System of Wheat Seedlings to Osmotic and Salt Stresses after Preliminary Priming of Grains with β-Aminobutyric Acid

Recently, progress has been made in establishing the molecular mechanisms of inducing plant resistance to pathogens by β-aminobutyric acid (BABA), which is considered one of the new plant stress metabolites. However, the mechanisms and even the phenomenology of BABA’s effect on plant resistance to major abiotic stressors remain insufficiently studied. This study aimed to determine the effect of priming wheat grains (Triticum aestivum L.) with BABA on their germination under osmotic (12% PEG 6000) and salt (120 mM NaCl) stress conditions as well as its connection with changes in the functioning of the antioxidant system of seedlings. Priming grains with an optimal concentration of BABA (0.5 mM) significantly mitigated the adverse effects of osmotic and salt stress on the germination rate of grains and the accumulation of shoot and root biomass but had hardly any effect on these indicators under normal conditions. When treated with BABA, the water content in the shoots of seedlings increased against the background of stresses that caused dehydration. Simultaneously, treatment of grains with BABA significantly reduced the level of superoxide radical generation by shoot cells and the accumulation of lipid peroxidation products (primarily malondialdehyde, or MDA) under conditions of osmotic and salt stress. Under the influence of BABA, an increase in superoxide dismutase (SOD) activity in shoots was observed under normal conditions and its stabilization under stress conditions. BABA treatment also prevented a decrease in catalase activity under osmotic and salt stress conditions and stabilized guaiacol peroxidase activity under osmotic stress. Additionally, BABA priming of grains contributed to an increase in the total content of phenolic compounds and anthocyanins in shoots under optimal seedling growth conditions and significantly mitigated the stress-induced decrease in the content of secondary metabolites. Correlation analysis and principal component analysis showed a close direct relationship between growth indicators and the activity of SOD and catalase and the content of phenolic compounds and anthocyanins. At the same time, these indicators were in close inverse correlation with MDA content. It was concluded that wheat grain priming with BABA is a promising and cost-effective biotechnological tool for managing plant stress in the early stages of development.