Salt stress greatly disturbs the growth, morpho-physiological, and biochemical performance of plants. However, different physiological processes and acclimation mechanisms can be induced under stress, while some of them can be modulated by the appropriate chemical stimulus. The objective of this study was to evaluate the impact of exogenous pretreatment with 10 mM l-glutamic acid (l-Glu) on the physiological and biochemical parameters of lentil (Lensculinaris Medik.) under 110 mM NaCl stress. Salt stress inhibited the growth and reduced the photosynthetic pigment (chlorophylls and carotenoids) level, water content, and survival of lentil seedlings during recovery from the stress. Salt stress also induced oxidative damage, as indicated by higher hydrogen peroxide and malonaldehyde contents and electrolyte leakage, by interrupting the antioxidant defense system and promoting the accumulation of toxic levels of Na⁺. However, l-Glu pretreatment mitigated the salt-induced damage in lentil seedlings by reducing the accumulation of Na⁺, maintaining ion homeostasis, and increasing the activities of antioxidant enzymes (catalase and ascorbate peroxidase). As a result, salt-induced oxidative damage was reduced, seedling growth and photosynthetic pigment contents were enhanced, and the survival rate of the lentil seedlings was improved in response to salt stress, indicating an ameliorative role for l-Glu in lentil seedling growth under salt stress.

Using phosphate fertilizers and wastewater as a source of irrigation and residuals from industries have considerably increased the level of cadmium (Cd) in soil which severely reduced the growth and yield of crop. L-glutamic acid (L-Glu), an amino acid, plays key roles in plant stress tolerance. Hence, the current study was conducted to determine the potential role of L-Glu pre-treatment in alleviating Cd-induced toxicity in lentil (Lens culinaris Medik.). Lentil seedlings were exposed to two doses of Cd (1 and 2 mM CdCl2) with or without 10 mM L-Glu pre-treatment. The results suggested that a high dose of Cd negatively affected the shoot dry weight, root dry weight, and photosynthetic pigments (chlorophylls and carotenoids). Furthermore, Cd stress induced severe oxidative damage, a reduction in catalase (CAT) activity and ascorbate (AsA) content, and accumulation of Cd in both the roots and shoots. Adding L-Glu protected the photosynthetic pigments of the lentil seedlings and thus improved the growth of the seedlings. In addition, L-Glu pre-treatment enhanced the ascorbate (AsA) content; increased the activity of enzymes such as catalase, ascorbate peroxidase, monodehydroascorbate reductase, and glutathione peroxidase. L-Glu was also reduced Cd uptake and translocation, which in turn alleviated the oxidative damage in the Cd-stressed seedlings indicated the potential role of this chemical. Results suggest that pre-treatment with L-Glu reduces Cd toxicity in lentil seedlings by inhibiting Cd accumulation and by reducing oxidative damage.

Trehalose 6-phosphate (T6P) regulates sugar levels and starch metabolism in a plant cell and thus interacts with various signaling pathways, and after converting T6P into trehalose (Tre), it acts as a vital osmoprotectant under stress conditions. This study was conducted using wheat (Triticum aestivum L. cv. Norin 61) and mustard (Brassica juncea L. cv. BARI sharisha 13) seedlings to investigate the role of Tre and T6P in improving salt and water deficit stress tolerance. The seedlings were grown hydroponically using Hyponex solution and exposed to salt (300 and 200 mM NaCl for wheat and mustard, respectively) and water deficit (20 and 12% PEG 6000 for wheat and mustard, respectively) stresses with or without Tre and T6P. The study demonstrated that salt and water deficit stress negatively influenced plant growth by destroying photosynthetic pigments and increasing oxidative damage. In response to salt and water deficit stresses, the generation of H₂O₂ increased by 114 and 67%, respectively, in wheat seedlings, while in mustard, it increased by 86 and 50%, respectively. Antioxidant defense systems were also altered by salt and water deficit stresses due to higher oxidative damage. The AsA content was reduced by 65 and 38% in wheat and 61 and 45% in mustard under salt and water deficit stresses, respectively. The subsequent negative results of salinity and water deficit can be overcome by exogenous application of Tre and T6P; these agents reduced the oxidative stress by decreasing H₂O₂ and TBARS levels and increasing enzymatic and non-enzymatic antioxidants. Moreover, the application of Tre and T6P decreased the accumulation of Na in the shoots and roots of wheat and mustard seedlings. Therefore, the results suggest that the use of Tre and T6P is apromising strategy to alleviate osmotic and ionic toxicity in plants under salt and water deficit stresses.