Function of Nodulation-Associated GmNARK Kinase in Soybean Alkali Tolerance

Soybean (Glycine max) is a vital crop that is rich in high-quality protein and edible oil for human nutrition and agriculture. Saline–alkali stress, a severe environmental challenge, significantly limits soybean productivity. In this study, we found that the nodule receptor kinase GmNARK enhances soybean tolerance to alkali stress besides nodulation. GmNARK could be induced by alkali stress in soybean roots. Ectopic overexpression of the GmNARK gene in Arabidopsis could significantly improve plant tolerance to alkaline stress. Moreover, overexpression or silencing of the GmNARK gene in soybean hairy roots also enhanced composite soybean plant tolerance to alkaline stress on plates and in soils. Additionally, overexpression of the GmNARK gene upregulated expression levels of the genes that are involved in the reactive oxygen species (ROS) signaling pathways. These findings provide a critical theoretical basis for further elucidating the role of GmNARK kinase in salt–alkali resistance and lay a foundation for improving soybean productivity under salt–alkali stress.