A Putative Plasma Membrane Na/H Antiporter GmSOS1 Is Critical for Salt Stress Tolerance in .

Soybean () is a staple crop and a major source of vegetable protein and vegetable oil. The growth of soybean is dramatically inhibited by salt stress, especially by the excessive toxic Na. Salt Overly Sensitive 1 (SOS1) is the only extensively characterized Na efflux transporter in multiple plant species so far. However, the role of GmSOS1 in soybean salt stress responses remains unclear. Herein, we created three mutants using the CRISPR-Cas9 system in soybean. We found a significant accumulation of Na in the roots of the mutants, resulting in the imbalance of Na and K, which links to impaired Na efflux and increased K efflux in the roots of the mutants under salt stress. Compared to the wild type, our RNA-seq analysis revealed that the roots of the showed preferential up and downregulation of ion transporters under salt stress, supporting impaired stress detection or an inability to develop a comprehensive response to salinity in the mutants. Our findings indicate that the plasma membrane Na/H exchanger GmSOS1 plays a critical role in soybean salt tolerance by maintaining Na homeostasis and provides evidence for molecular breeding to improve salt tolerance in soybean and other crops.