Overexpression of GmSCAMP4 Enhances the Tolerance of Soybeans to Low Phosphorus Stress.

The secretory carrier membrane proteins (SCAMPs), which are an evolutionarily conserved transmembrane protein family ubiquitously present in plants and animals, are implicated in various abiotic stress responses. However, their functional roles in plant adaptation to phosphate limitation remain unexplored. Through systematic genomic and transcriptomic analyses of soybean under low-phosphate (LP) stress, we identified GmSCAMP4 as a key LP-responsive candidate, exhibiting root-predominant expression and strong transcriptional induction under phosphorus deprivation. Functional validation revealed that GmSCAMP4 overexpression in soybean hairy roots significantly enhanced LP tolerance, marked by optimized root architecture, elevated biomass production, and increased phosphorus accumulation. Conversely, RNAi-mediated knockdown of GmSCAMP4 exacerbated LP sensitivity, mirroring inverse phenotypic trends. Molecular investigations demonstrated that GmSCAMP4 orchestrates the expression of important LP-responsive genes and physically interacts with GmZFP2, modulating its transcription level during phosphate stress. These findings collectively establish GmSCAMP4 as a central regulator of soybean's phosphate starvation response, driving adaptive root remodeling to enhance phosphorus acquisition efficiency. This study not only elucidates a novel molecular mechanism underlying LP adaptation but also positions GmSCAMP4 as a strategic genetic target for breeding phosphorus-efficient soybean varieties.