Succinic acid as a central regulator of stress responses, fruit development, and sustainable biotechnology

Abstract Succinic acid (SucA), a key intermediate of the tricarboxylic acid (TCA) cycle, has emerged as a multifunctional metabolite with roles extending far beyond energy metabolism. In plants, SucA regulates mitochondrial function, ATP generation, and reactive oxygen species (ROS) signaling, thereby linking redox balance with salicylic acid-mediated defense pathways. Through its integration with the γ-aminobutyric acid (GABA) shunt, SucA contributes to carbon–nitrogen balance, rapid energy reprogramming, and stress-responsive metabolic adaptation. These functions highlight SucA as both a metabolic intermediate and a dynamic signaling molecule at the interface of primary and secondary metabolism. Recent evidence from apple, citrus, tomato, and date palm demonstrates that SucA accumulation enhances tolerance to abiotic stresses such as drought, salinity, and temperature extremes, while also contributing to biotic resistance by reinforcing defense gene expression and phytohormonal crosstalk. During fruit development and ripening, SucA plays a pivotal role in organic acid balance, flavor determination, and postharvest physiology, influencing storability and consumer quality traits. Parallel advances in microbial fermentation and metabolic engineering have further positioned SucA as a high-value bio-based platform chemical with applications in agriculture, pharmaceuticals, and sustainable industry. Despite its importance, key questions remain regarding the molecular mechanisms of SucA signaling and its crop-specific regulation. Future research integrating omics, metabolic flux analysis, and synthetic biology is essential to fully elucidate SucA dynamics and harness its dual potential as a plant biostimulant and renewable industrial resource. Collectively, SucA represents a critical nexus linking metabolism, stress resilience, and bioeconomy innovation.