Regulation of L-Glutamic Acid (L-Glu) on Physio-Biochemical Metabolism and Phenolics Biosynthesis in Wheat Sprouts Under NaCl Stress

The physio-biochemical metabolism of wheat sprouts under NaCl stress and its alleviation mechanism were studied under different concentrations of L-Glu. Results showed that NaCl stress induced oxidative damage to wheat sprouts. However, L-Glu decreased the accumulation of MDA, H2O2 and O2−· under NaCl stress, inhibited the absorption of Na+ by wheat sprouts and promoted the synthesis of free amino acids. In addition, L-Glu also increased the activities of phenylalanine ammonia lyase (PAL), cinnamic acid 4-hydroxylase (C4H) and 4-coumarate coenzyme A ligase (4CL) in wheat sprouts under NaCl stress, thus promoting the biosynthesis of phenolics. Specifically, after treatment with 0.1 mmol·L−1 L-Glu, the contents of ferulic acid and p-coumaric acid increased by 19.59% and 11.32% respectively, the content of dihydroquercetin increased by 8.5%, and the total flavonoid content was 2727.06 μg·g−1 DW, which increased by 10.01% compared with the NaCl stress group on the 6th day of germination. This research provides a food-grade strategy to improve wheat sprout nutrition and stress tolerance, advancing functional plant-based foods and amino acid-mediated stress alleviation.