An Indole‐3‐Acetic Acid‐Amido Synthetase, GmGH3.2, Negatively Regulates Salt Tolerance in Soybean

Soil salinization severely restricts soybean growth and productivity. Therefore, uncovering salt‐tolerance genes and their regulatory mechanisms is critical for breeding salt‐tolerant soybean varieties. In this study, a genome‐wide association study (GWAS) was conducted across four environments, and 7 quantitative trait locus (QTLs) associated with salt‐tolerance traits were identified. Furthermore, the candidate gene GmGH3.2 was cloned at qSTG2‐1 , which encodes an indole‐3‐acetic acid‐amido synthetase. Functional analyses revealed that interfering with expression of GmGH3.2 in soybean hairy roots significantly enhanced salt tolerance, as evidenced by an increase in total root length, surface area, volume, and tip number. Conversely, the overexpression of GmGH3.2 markedly inhibited root growth under salt stress when compared with the control. Additionally, GmGH3.2 negatively regulates salt tolerance by influencing K + ‐Na + homeostasis and the expression of six salt tolerance‐associated genes ( GmSOS1 , GmNHX1 , GmSALT3 , GmAKT1 , GmHKT1 , and GmSKOR ). Moreover, GmGH3.2 interacts with GmKH1 in the nucleus and may collaboratively participate in the regulation of salt tolerance. In summary, our findings establish GmGH3.2 as a negative regulator of salt tolerance in soybean, providing valuable theoretical insights and genetic resources for molecular breeding of salt‐tolerant cultivars.