Advances in Fruit Organic Acid Metabolism and Molecular Regulation in Fruit Trees

Organic acids are the core of fruit flavor quality and cell metabolism, but a comprehensive review of their metabolism and regulatory networks in fruit trees is still limited. Here, we systematically summarized the biosynthesis, degradation and transport of major organic acids in fruits of horticultural crops. We focused on the distribution and molecular regulation of organic acids in citrus, pome fruits, stone fruits, grapes and tropical–subtropical fruits, and emphasized the regulation of transcription factors, epigenetic modifications and environmental signals. We also evaluated the progress of various omics strategies for dissecting organic acid metabolism and identifying key regulatory genes. Finally, we discuss the current research gaps and propose future directions for multi-gene editing and molecular design breeding. This review provides a theoretical framework for improving fruit flavor quality and breeding excellent varieties.