GABA Enhances Muskmelon Chloroplast Antioxidants to Defense Salinity-Alkalinity Stress

Abstract

Salinity-alkalinity stress is a pivotal factor influencing plant growth, development, and yield. γ-Aminobutyric acid (GABA) protects plants against a variety of environmental stresses. However, it is remains largely unknown whether exogenous GABA increases the tolerance of Cucumis melon L. seedlings via effects on the chloroplast antioxidant system. In this study, the role of exogenous GABA application on the malondialdehyde content and antioxidant enzyme activities and the ascorbate-glutathione (AsA-GSH) cycle in seedlings of muskmelon was investigated. Plants were treated with foliar spraying of GABA (50 mM) under control or salinity-alkalinity stress conditions. Salinity-alkalinity stress induced cellular membrane damage. Treatment with GABA protected muskmelon seedlings from salinity-alkalinity stress by enhancing antioxidant enzyme activity and reducing malondialdehyde content. These effects of GABA resulted in maintenance of the membrane integrity of the muskmelon seedling. In addition, the status of both GSH and AsA redox played key roles in the regulation of the oxidative stress response in muskmelon seedlings under salinity-alkalinity stress.