紫外联合酸胁迫红小豆萌发富集GABA工艺优化及其合成通路分析OA

This study aimed to investigate the effect of combined ultraviolet(UV)and acid stress on GABA enrichment in germinating adzuki beans(Vigna angularis).Single-factor experiments were conducted to analyze the impacts of germina-tion time,temperature,UV stress duration,and citric acid concentration on GABA synthesis.Response surface method-ology was applied to optimize the germination conditions,and the activities of related metabolic enzymes and the GABA synthesis pathway were analyzed.The results indicated that the optimal conditions for GABA enrichment in germinating adzuki beans under combined UV and acid stress was as follows:Germination time of 73 h,germination temperature of 34℃,UV stress duration of 4.5 h,and citric acid concentration of 0.45 mmol/L.Under these conditions,the maximum GABA content was 159.83±1.32 mg/100 g(dry weight),which was 6.32 times higher than that in non-germinating adzuki beans.Enzyme activity assays demonstrated that the activity of DAO,a key rate-limiting enzyme,was significantly increased at 24 h of germination in the combined treatment group.In comparison,the activities of GAD and PAO peaked at 48 h.Although their activities slightly decreased afterwards,the catalytic capacity was maintained,leading to the maximum GABA content at 73 h.To further explore the biosynthetic mechanism of GABA enrichment in germinating adzuki beans under combined UV and acid stress,transcriptomic analysis was performed.The analysis revealed that this combined stress promoted GABA synthesis primarily by regulating eight pathways including MAPK signaling pathway-plant,glutathione metabolism,and nitrogen metabolism.This study confirmed that combined UV and acid stress could significantly promote GABA enrichment in germinating adzuki beans.It provides a theoretical reference for elucidating its metabolic regulation mechanism and the processing of functional adzuki bean products.