Integrated metabolomic and transcriptomic profiling with organic acid quantification unveils metabolic signatures and basis of sour flavor formation in Begonia edulis

Begonia edulis possesses dual values in ornamental horticulture and edible applications. Its fresh leaves and petioles demonstrate a sour flavor profile, making them preferable among consumers of wild vegetables. Previous investigations into the edibility of Begonia species have primarily concentrated on fundamental nutrient profiling, with limited elucidation of the metabolic constituents responsible for their characteristic sour flavor. Furthermore, the prevailing assumption that oxalic acid is the primary contributor to this sourness has significantly hampered their wider application for edible purposes. To address these gaps and achieve a more comprehensive understanding of Begonia metabolism, this study employed an integrated metabolomics and transcriptomics approach to analyze the metabolic profiles and gene expression patterns in leaves, petioles, and rhizomes of B. edulis . A total of 1818 metabolites and 28 structural gene families associated with organic acid biosynthesis were identified. The UPLC-based quantification of organic acids subsequently revealed the tissue-specific high accumulation of citric, malic, quinic, tartaric, and ascorbic acid in leaves and petioles. This accumulation pattern is likely a key in the formation of the distinctive sour flavor of B. edulis . Furthermore, the antioxidant capacity assays showed that the petioles and leaves had higher antioxidant activity than the rhizomes, indicating coordinated regulation of organic acids accumulation and antioxidant metabolism. In conclusion, this study established metabolic profiles for edible tissues of B. edulis , providing a reference for understanding their metabolic composition and the formation of its sour flavor characteristic.