Boosting NADPH with GABA: Converting aged seeds to functional soybean sprouts

Seed aging impairs soybean germination and sprout nutrition. This study investigated how γ-aminobutyric acid (GABA) revitalizes aged seeds via pentose phosphate pathway (PPP) activation. Aged soybean seeds were treated with 0.1 mM GABA, 20 μM dehydroepiandrosterone (G6PDH inhibitor), or their combination, with pharmacological inhibition confirming PPP dependency. GABA restored germination from 35% to 72%, enhanced G6PDH activity to 225% of aged control, and upregulated GmG6PD2 expression (6.8-fold). Antioxidant capacity (FRAP) recovered to 83% of fresh seed levels, with AsA/DHA and GSH/GSSG ratios restored from 2.6 to 6.3 and 3.2 to 9.2, respectively. NADPH/NADP⁺ ratio increased from 1.4 to 3.4. Metabolomics (3876 metabolites) revealed GABA specifically activated PPP intermediates and isoflavone biosynthesis. Notably, endogenous GABA increased ∼3-fold, producing dual-functional sprouts with elevated antioxidants and high GABA content. This study demonstrates GABA revitalizes aged seeds by activating PPP to replenish NADPH, offering a promising strategy to mitigate storage losses.