The GmEIN3.1-GmERF3-GmABCI17 module coordinately regulates soybean root development and cadmium tolerance through the ethylene signaling.

Abstract

Soybean (Glycine max) is a critical oil crop and a key source of fat and protein for both humans and animals. Cadmium (Cd) stress is a severe heavy metal stresses limiting root growth and yield. Significant variations exist in Cd tolerance among different soybean varieties. However, the molecular mechanisms underlying Cd-induced root growth inhibition and Cd accumulation remain elusive. Here, we identified that the GmEIN3.1-GmERF3-GmABCI17 module in the ethylene signal transduction pathway coordinately regulates soybean root growth and Cd accumulation. We found Cd stress positively regulates the expression of GmEIN3.1 (Glyma.13G076700), which inhibits root development but reduces Cd accumulation and enhances Cd tolerance. Multiple lines of experimental evidence demonstrate that GmEIN3.1 represses the expression of GmERF3 (Glyma.14G050100), a transcription factor that promotes root development. In turn, GmERF3 binds to and suppresses the expression of the ABC transporter GmABCI17 (Glyma.08G055000), a Golgi-localized protein with Cd efflux transporter activity. Overexpression of GmABCI17 promotes Cd efflux, thereby reducing intracellular Cd accumulation and enhancing Cd tolerance. Collectively, the GmEIN3.1-GmERF3-GmABCI17 transcriptional cascade coordinates Cd-induced root growth inhibition, restricts Cd accumulation, and Cd tolerance in soybean. It provides exploitable targets for breeding low-Cd soybean cultivars and addresses critical food safety concerns.