Identification of Key Regulators Mediating Gamma-Aminobutyric Acid (GABA) and Organic Acid Accumulation in Strawberry.

Growing market demand exists for strawberry, with nutrient-rich and health-promoting properties, beyond mere taste and flavor. Genetic biofortification is a powerful strategy to enhance nutrient metabolites in strawberry. Both GABA and organic acids contribute to human health by supporting nervous system relaxation and enhancing metabolic and digestive functions, respectively. However, the regulatory mechanisms underlying their accumulation remain poorly understood. In this study, we analyzed the accumulation patterns of GABA and organic acids across four fruit developmental stages in two representative cultivars, 'Monterey' and 'Benihoppe'. Ripening 'Benihoppe' fruits accumulated higher levels of GABA and citric acid, whereas 'Monterey' fruits contained more malic acid. Integrated transcriptome analysis identified key structural genes and transcription factors (TFs) involved in GABA biosynthesis. Notably, functional characterization revealed that FaGAD4 significantly promotes GABA accumulation and simultaneously enhances the content of anthocyanin and ascorbic acid (AsA). Overall, this study provides novel insights into the regulatory mechanisms of GABA accumulation in strawberry fruit and identifies FaGAD4 and potential TFs as valuable genetic targets for molecular breeding.