The role of glycolate oxidase in regulating Arabidopsis thaliana response to short-term salt stress

Salt stress is a major abiotic factor limiting plant growth and productivity. One of the primary consequences of salinity is the enhanced production of reactive oxygen species (ROS). This study investigates the role of glycolate oxidase (GOX), a key enzyme in photorespiration and a source of ROS, in the salinity response of Arabidopsis thaliana. We used two GOX T-DNA insertion mutants, gox1 and gox2, alongside wild-type (WT) plants, grown hydroponically under control conditions or exposed to 100 mM NaCl for 24 h. Results showed that shoot and root fresh weight did not differ significantly between genotypes and after 24 h of NaCl treatment. In addition, both mutants, particularly gox2, accumulated less Na⁺ and Cl^- in shoots and roots than WT. This result was supported by ion flux analysis in roots. This fact was associated with the upregulation of key ion transporters: NHX1 (Na⁺compartmentalization), SOS1 (Na⁺ exclusion), and KUP11 and HAK5 (K⁺ uptake). Additionally, gox2 showed differential regulation of nitrate/Cl^- transporters, with downregulation of NPF2.4, SLAH1, and SLAH3 and upregulation of NPF2.5 and NPF7.2. Furthermore, gox2 exhibited reduced oxidative damage and increased peroxidase activity under salt stress. These findings suggest that GOX2 expression may regulate plant resilience to salinity by improving ion homeostasis and antioxidative responses.