Ethylene-Responsive Transcription Factor 013 Regulates Physiological and Molecular Responses to Salt Stress in Arabidopsis thaliana

Soil salinity severely limits plant growth by disrupting cellular homeostasis and inducing oxidative damage. Although ethylene-responsive transcription factors (ERFs) are central regulators of stress responses, the function of ERF013 in salt stress responses remains poorly understood. In this study, we investigated the role of ERF013 in Arabidopsis thaliana using ERF013 overexpression lines (OE-ERF013) and genome-edited (ge-erf013) under 250 mM NaCl stress, in comparison with wild-type control (CK) and salt-treated wild-type (WT) plants. Under salinity stress, OE-ERF013 plants maintained vigorous shoot and root growth, exhibiting a 17% increase in shoot fresh weight and a 100% in root fresh weight relative to WT-T plants, whereas ge-erf013 mutants displayed severe growth inhibition. Salt stress markedly elevated superoxide (O2−) and hydrogen peroxide (H2O2) levels in WT-T (62% and 134%) and ge-erf013 plants (122% and 193%) compared with CK, while OE-ERF013 plants showed a significant reduction in O2−·and H2O2 levels, which decreased by 34% and 64%, respectively, relative to WT-T. Improved redox homeostasis in OE-ERF013 plants was associated with enhanced catalase (CAT) and superoxide dismutase (SOD) activities (55% and 44%), increased DPPH radical-scavenging activity (62%), maintained total antioxidant capacity (ABTS), and reduced lipid peroxidation, whereas ge-erf013 plants exhibited a 47% increase in malondialdehyde (MDA) content relative to WT-T. Furthermore, OE-ERF013 plants displayed reduced electrolyte leakage and sustained higher relative water content (RWC), with only a 15% decline under salt stress. Transcript analysis revealed strong upregulation of key ion homeostasis genes (SOS1, SOS2, NHX1, and HKT1) in OE-ERF013 plants, while their expression was suppressed in ge-erf013 mutants relative to WT-T. Additionally, OE-ERF013 plants accumulated higher abscisic acid (ABA) levels and showed increased expression of ABA biosynthesis-related genes (ATAO3 and ATABA3), accompanied by enhanced osmotic adjustment through elevated proline, soluble sugars, and sucrose accumulation, as well as improved chlorophyll stability. Collectively, these results demonstrate that ERF013 acts as a positive regulator of responses to salinity by coordinating ABA signaling, antioxidant defense, ion homeostasis, and osmotic regulation in Arabidopsis thaliana.