Modulation of the Antioxidant Defense System by Exogenous <span style="font-variant: small-caps">l</span>-Glutamic Acid Application Enhances Salt Tolerance in Lentil (<i>Lens culinaris</i> Medik.)

• Main Authors: Jannatul Fardus, Md. Shahadat Hossain, Masayuki Fujita
• Format: Article
• Language: English
• Published: MDPI AG 2021-04-01
• Series: Biomolecules
• Subjects: salt stress; ROS; oxidative damage; ion homeostasis; antioxidant defense system; amino acid
• Online Access: https://www.mdpi.com/2218-273X/11/4/587

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 <span style="font-variant: small-caps;">l</span>-glutamic acid (<span style="font-variant: small-caps;">l</span>-Glu) on the physiological and biochemical parameters of lentil (<i>Lens</i><i>culinaris</i> 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, <span style="font-variant: small-caps;">l</span>-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 <span style="font-variant: small-caps;">l</span>-Glu in lentil seedling growth under salt stress.