New Observations on the Integrity, Structure, and Physiology of Flesh Cells from Fully Ripened Grape Berry

Abstract

The physiological/structural status of the soft ripened berry is still a matter of debate. The isolated mesocarp cells from ripened berries of both wine and table varieties were studied by bright-field, fluorescence, and confocal microscopy and flow cytometry to highlight the organization of berry flesh cell, function, and viability. Flow cytometry analysis confirmed that protoplasting from grape berry mesocarp tissue yields a single heterogenous population of intact and viable cells. Also, the integrity of the plasma membrane and the architecture and complexity of the intracellular membranous system were shown by FM1-43 staining coupled to confocal microscopy imaging. The observed incorporation of the fluorescent glucose analogue 2-NBDG suggests that endocytosis is involved in the transport and intracellular compartmentation of apoplastic sugars. Neutral Red staining confirmed the intricate organization, size, diversity, and integrity of the vacuolar apparatus that is probably related to the multifaceted roles of the vacuoles in the developing fruit.