Plasmodesmatal Structure and Function in Nectaries

Abstract

Elucidation of how water and solutes move from cell to cell and how stimuli are transmitted through plants constitutes a major question in plant cell biology. In the multicellular bodies of higher plants, cells are enclosed by a rigid cell wall which does not readily permit changes in shape, neither does it favour the exploitation of mechanical pumping mechanisms to face nutritional requirements, such as pinocytosis and reverse pinocytosis common in animal cells. Facing this inherent restriction, plant cells have instead evolved and utilised effectively alternative structures for their intercellular communication, the plasmodesmata. Plasmodesmata are fine strands of cytoplasm bounded by the plasma membrane that connect the living cells with their living neighbours by penetrating through perforations of the intervening cell walls. The presence of plasmodesmata subdivides the plant body into two major compartments, the symplast, comprising the interconnected protoplasts bounded by the continuous plasma membrane, and the apoplast, consisting of the non-living compartment outside the plasma membrane (for details see Gunning and Steer 1975, Gunning 1976).