Transcriptomic and Metabolic Insights into the Regulation of Lignin and Cellulose Biosynthesis by Exogenous Potassium in Soybean Stems

In this study, the soybean cultivar "Heinong 40" was evaluated under two potassium (K) regimes: low potassium (K4) and sufficient potassium (K28). Through anatomical profiling, physiological characterization, and integrated transcriptomic and metabolomic analyses, we elucidated the phenotypic and molecular mechanisms by which exogenous potassium regulates the mechanical development of the fourth (D-4) internode.

The results demonstrated that K28 treatment significantly thickened the D-4 internode, enhanced K accumulation, enlarged vascular bundle areas, and thickened the secondary cell walls of mechanical tissues, accompanied by 33.19% and 52.05% increases in cellulose and lignin contents, respectively. Multi-omics integration further revealed that sufficient K supply stimulated sucrose catabolism and glycolytic flux, thereby supplying carbon precursors and energy for cellulose biosynthesis.