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

Abstract

Softening is one of the most significant changes determining the quality and postharvest life in strawberry. Though some studies have attempted to characterize the cell wall modifications accompanying firmness loss during storage, the reports on polysaccharide disassembly are widely variable. Herein, we determined the changes in firmness, stiffness, cell wall solubilization, depolymerization and composition in the Core and External zone of strawberry receptacle during storage. Core tissues were firmer and stiffer and showed more softening after storage than the External zone. Softening occurred in the fruit Core with a more extensive loss of non-cellulosic (pectin and hemicelluloses) polysaccharides. Remarkable differences in wall degradation were identified between fruit regions: firmness loss in the External zone occurred with extensive solubilization of hemicelluloses (loosely-bound) and pectin and massive arabinose loss, but with very limited polysaccharide depolymerization. In contrast, softening of the fruit Core showed substantial depolymerization of both hemicelluloses and polyuronides (water-soluble). Moreover, xyloglucans were the most degraded hemicelluloses within the Core zone as opposed to xylan-type cross-linking glycans within the External region. Altogether, results dissect, for the first time, the differences in postharvest wall disassembly events between the Core and External region of the strawberry.