Ginger heterografting induces LOX2 succinylation to develop novel low-off-flavor soybean varieties

Developing soybean cultivars with reduced off-flavor is a vital agricultural goal, as lipid-derived volatile compounds significantly impair the sensory quality of processed soy products. This study established an interfamily grafting system utilizing soybean scions and ginger (Zingiber officinale) rootstocks to generate novel low-off-flavor germplasm. A modified side-plug grafting technique achieved a survival rate of 65.97%, forming functional vascular connections. Xylem reconnection occurred six days post-grafting, while phloem reconnection was observed at three days, facilitating bidirectional metabolite transport. Metabolomic analyses revealed significantly elevated levels of rootstock-derived metabolites, particularly nicotinamide (with a 118.54-fold increase) and tetracosanoic acid (5.47-fold increase), in heterografted soybean scions, potentially inducing heritable phenotypic variations. Mechanistically, increased succinylation at lysine residues K257, K263, and K472 within the lipoxygenase 2 (LOX2) protein reduced its enzymatic activity by 58.6%, thereby inhibiting the formation of off-flavor precursors. After five generations of self-pollination, stable graft-derived lines (e.g., DS222) demonstrated a 61.33% to 89% reduction in total volatile off-flavor compounds and a 45% to 68% improvement in sensory preference scores compared to the original scion (HN48). These findings suggest that interfamily grafting enhances soybean quality through metabolic crosstalk and post-translational modifications.