Work

Alkalization and cell wall remodeling mark the maturation of the fruit abscission zone in table olive

Year: 2026

Type: article

Abstract: Abscission zones mediate organ separation through coordinated changes in cell wall architecture and intercellular signaling. To elucidate mechanisms of fruit abscission zone (FAZ) transitions preceding fruit detachment in the non-climacteric fruit olive (Olea europaea), we integrated physiological, transcriptomic, and cellular analyses during natural maturation and after ethylene treatment. A mesocarp-subtraction RNA-seq strategy uncovered a FAZ-enriched module of 733 genes, representing core regulators of FAZ maturation. Induction of β-1,3-glucanase genes corresponded with elevated glucanase activity and callose depletion at plasmodesmata, indicating increased symplastic signaling required to initiate the abscission. A previously undocumented rise in cytoplasmic and apoplastic pH of the olive FAZ, coupled with reduction of low-methylesterified homogalacturonan, represents a hallmark of pH-dependent wall remodeling. Transcriptomic enrichment of transporters and pH-responsive wall-modifying enzymes positions pH homeostasis as a central regulator upstream of wall reconfiguration. Concurrent activation of pectate lyases and key phenylpropanoid pathway enzymes suggests a dual remodeling trajectory involving reduction of de-methylesterified pectin, which weakens intercellular cohesion, and localized lignin deposition, defining the separation boundary. Our findings establish a conserved molecular circuit that confers ethylene competence to the FAZ and a mechanistic framework in which symplastic connectivity, pH-driven enzymatic activation, and modulation of wall polymer chemistry orchestrate FAZ maturation and fruit detachment in table olive.

Source: Journal of Experimental Botany

DOI: 10.1093/jxb/erag233