Exogenous application of glutathione and gamma amino-butyric acid alleviates salt stress through improvement in antioxidative defense system and modulation of CaXTHs stress-related genes
Musarrat Ramzan, Anis Ali Shah, Muhammad Zaheer Ahmed, Muhammad Adnan Bukhari, Liaqat Ali, Ryan Casini, Hosam O. Elansary
Abstract
• Salt stress reduced growth and physiological properties of Capsicum annum L. • Glutathione (GSH) and Gamma aminobutyric acid (GABA) reduced salt stress by decreasing electrolyte leakage, malondialdehyde content. • GSH and GABA enhanced the expression profiles of Caxths stress-related genes ( CaXTH1, CaXTH2 , and CaXTH3 ) and ATPase activity under salt stress. Globally, soil salinization has drastically affected the growth and production of many crops. A major challenge for environmentalists is mitigation of stress caused by the saline soil. Non-protein amino acids, namely glutathione (GSH) and γ-aminobutyric acid (GABA), accumulate in plants facing abiotic stresses. In the current study, it was hypothesized that non-antioxidant enzymes such as GSH and GABA at different concentrations in NaCl-stressed plants could effectively reduce salt-induced effects on chili ( Capsicum annuum L.) plants. This exploratory study focused on effects of exogenic GSH and GABA on photosystem-II performance, light energy distribution, osmoprotectants, and quenching of H 2 O 2 content in C. annuum seedlings induced by salt stress. In addition, the role of GSH and GABA in alleviating salt stress was also studied. Exogenous GSH and GABA enhanced plant salt tolerance index through reduction in electrolyte leakage (EL), malondialdehyde (MDA) content and incrementation in soluble components of sugar, proline and amino acid. Application of GSH and GABA also reduced H 2 O 2 content in salinity treated C. annuum seedlings by enhanced anti-oxidative defensive enzyme activity. Exogenous supplementation of GSH and GABA enhanced both the transfer of absorbed light towards PSII core and its utilization for photosynthetic electron transport, and finally optimized Fv/Fm ratio, increased photochemical quenching (qP) and PSII efficiency (YII) while decreased non-photochemical quenching (NPQ). Supplementation of GSH and GABA resulted in pronounced expression of CaXTHs stress-related genes ( CaXTH1, CaXTH2 and CaXTH3 ) and ATPase activity in C. annum plants exposed to salt-induced stress. In conclusion, exogenous application of GSH and GABA enhances salt tolerance level of C. annuum by improving antioxidant defense systems, ATPase enzymes and expression of CaXTH genes.