Metabolomic analysis reveals that exogenous L-valine enhances saline-alkali tolerance in germinating adzuki bean (Vigna angularis)

Abstract At present, there is limited information available regarding the response of adzuki bean to saline-alkali stress. Here, we explored the saline-alkaline stress response mechanisms of two adzuki bean germplasms, namely the tolerant XD168 and the sensitive XD8, which were previously characterized by our laboratory, through a multi-level approach combining phenotypic evaluation, physiological assays, and metabolomic profiling. Phenotypic assays showed that stress inhibited germination traits in XD8, whereas XD168 exhibited stable germination. Physiological indices indicated that stress caused more severe damage to XD8 than to XD168. Further metabolomic profiling identified amino acid metabolism as a key pathway in the saline-alkali stress response. L-valine was positively correlated with germination traits and CAT activity, but negatively correlated with stress-related indices, such as O 2 .- , H 2 O 2 , and malondialdehyde contents. In addition, seed priming with exogenous L-valine significantly improved the germination rate, radicle length, vigor index, and CAT activity of adzuki bean germplasms XD31 and XD35 under saline-alkali stress, while simultaneously reducing reactive oxygen species accumulation, malondialdehyde content. Collectively, our findings reveal that L-valine may enhance saline-alkali tolerance in adzuki bean by potentially boosting CAT-mediated reactive oxygen species scavenging and alleviating oxidative damage, providing physiological and metabolic insights into amino acid-regulated stress resistance in plants.