Overexpression of GmJAZ5 Enhances Salt Tolerance in Soybean

Soil salinization poses a significant challenge to soybean production, yet the regulatory mechanisms underlying root responses to salt stress remain incompletely understood. In this study, we analyzed the expression patterns, subcellular localization, and functions of overexpressed GmJAZ5 in soybean roots. Under salt stress, GmJAZ5 expression was consistently downregulated in leaves, whereas roots exhibited initial suppression followed by a recovery phase. The GmJAZ5 protein was localized to the nucleus. GmJAZ5 overexpression markedly attenuated salt-induced growth inhibition and enhanced the activities of antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), and catalase (CAT). This manipulation also reduced malondialdehyde (MDA) accumulation and decreased both Na⁺ content and the Na⁺/K⁺ ratio in leaves. Additionally, it exerted tissue-specific effects on jasmonic acid (JA) and abscisic acid (ABA) levels. These results indicate that overexpression of GmJAZ5 enhances salt tolerance in soybean by strengthening antioxidant defenses, limiting Na⁺ translocation, and modulating phytohormone homeostasis, highlighting its potential as a candidate gene for breeding salt-tolerant soybean varieties.