Abstract
The water potential gradient in plants is generated mainly by transpiration and growth. Growth and metabolism occur in the aqueous medium provided by cells, and water flow is affected by complex multicellular structures. There are three pathways for water and solutes to move in roots. The apoplastic pathway refers to flows in the cell wall around cell protoplasts, whereas the syplasmic pathway is defined by a transport from cell to cell via plasmodesmata. In the transcellular pathway, water must cross two cell membranes per cell layer as well as the wall between adjacent cells. When HgCl2 was added to bathing solution of actively growing wheat seedlings, cell elongation of leaves was temporarily inhibited and subsequent leaf growth recovery was observed under transpiring conditions. Water pathways for growth process in leaves and the involvement of aquaporins are discussed.
