Functional Characterization of Soybean MADS-Box Gene GmMADS3  in Salt Tolerance

Soil salinization is a major abiotic stress severely limiting global crop productivity, particularly in legumes such as soybean. In this study, we characterized the soybean MADS-box transcription factor GmMADS3 and its role in salt tolerance. GmMADS3 encodes a protein with conserved MADS and K domains, and its expression was strongly induced by salt stress. Overexpression GmMADS3 in Arabidopsis thaliana and soybean promoted seed germination and seedling survival under high salinity, maintained photosystem II (PSII) efficiency, enhanced non-photochemical quenching, and reduced reactive oxygen species (ROS) accumulation. Transgenic plants exhibited higher superoxide dismutase (SOD) and peroxidase (POD) activities, lower malondialdehyde (MDA) content, and increased proline accumulation, consistent with strengthened antioxidant capacity and osmotic adjustment. Transcript analyses further reveal up-regulation of multiple salt-responsive genes in both species. These findings indicate that GmMADS3 enhances salt tolerance through photoprotection, antioxidant defense, osmotic homeostasis, and regulate stress-responsive pathways, providing a promising target for breeding salt-tolerant soybean.