Cell wall disassembly events accompanying softening in the core and external zones of the strawberry fruit receptacle

Softening is one of the most important changes determining the quality and postharvest life of strawberry. Though some studies have characterized the cell wall modifications accompanying firmness loss during storage, the reports on polysaccharide disassembly are widely variable and in some cases contradictory. To further understand strawberry postharvest softening, conducted a comprehensive cell wall analysis including polymer solubilization, depolymerization and composition of the Core and External zones of fruit´s receptacle during storage. Core tissues were firmer and stiffer and softened more than the External receptacle zone. Wall dismantling was remarkably different depending on the region evaluated. Core tissues showed greater losses and size downshift of hemicelluloses as well as more extensive depolymerization of pectin. Instead, softening in the External region occurred with limited depolymerization and with massive loss of arabinose and xylose. Xyloglucans showed active turnover in the Core, whereas xylans were the most degraded hemicelluloses in the External region. Results show that each discrete region of the strawberry fruit receptacle has a unique sequence of biochemical wall dismantling events leading to postharvest softening.