Major Factors Governing Growth in Pea Epicotyl Segments: The Cell Wall Mechanical Property, the Osmotic Potential and Solute Movement in the Apoplast.

Abstract

The rate of enlargement of pea stem segments was calculated with four parameters obtained by a stress-relaxation analysis of the cell wall and compared it with that observed under a certain experimental condition. Pea (Pisum sativum L.) stem segments were incubated in 0.4M mannitol for 120min at 0°C, then transferred to buffer at 0°C in order to create an in vivo turgor pressure. The observed enlargement was slower than the calculated processes, since mannitol in the segment apoplast diffused out gradually. If the gradual increase in turgor pressure due to diffusion of mannitol was introduced to the computation, the calculated enlargement process fits well the observed one. It is concluded that segment enlargement was physically described by the mechanical property of the cell wall, the osmotic potential and solute movement in the apoplast.