Regulatory role of cell wall–modifying enzymes in fruit softening and texture development: A comprehensive review

Fruit softening is a defining feature of ripening that directly affects texture, sensory quality, shelf life, and postharvest losses. At the cellular level, softening results primarily from structural modifications of the primary cell wall and middle lamella. These changes are mediated by a coordinated network of cell wall–modifying enzymes that act on pectins, hemicelluloses, and cellulose, leading to weakening of cell-to-cell adhesion and wall integrity. Key enzymes involved in this process include polygalacturonase, pectin methylesterase, pectate lyase, β-galactosidase, cellulase, xyloglucan endotransglycosylase/hydrolase, and expansins. Their activities are tightly regulated by developmental signals, hormonal pathways—particularly ethylene—and environmental factors. This review provides an in-depth synthesis of the structural basis of fruit softening, the roles and regulation of major cell wall–modifying enzymes, and differences between climacteric and non-climacteric fruits. Implications for texture development, shelf-life control, and postharvest management strategies are discussed. Understanding the regulatory mechanisms governing cell wall disassembly is essential for improving fruit quality and reducing postharvest losses.