Year: 1993
Type: article
Abstract: Plant cells are constrained by a tough, yet flexible, polymeric wall that determines cell shape, permits high turgor pressures to develop, and confers important mechanical advantages.However, these walls present a special problem to growing cells, which must expand and deform this "exoskeleton" to enlarge and, yet, at the same time keep the wall strong enough to withstand the large mechanical stresses that arise from cell turgor pressure.These stresses may exceed 10' N m-' (1000 atm) because the expansive forces generated by turgor are focused on the thin cell wall.Because of this mechanical situation, plant cells cannot simply deposit more material to the wall to make it extend.Rather, the polymeric network that confines the cell must shear (slip) to create new surface area while still maintaining sufficient structural integrity to resist large tensile forces.This seems like a perfect recipe for disaster: local wall expansion would cause local wall thinning and, consequently, further weakening and expansion, leading to an aneurysm or a blowout of the wall.The fact that this rarely happens implies a built-in braking action in the mechanism of wall surface expansion.Current models of the walls of vascular plants show three interwoven polymeric networks: a network of cellulose microfibrils linked together by matrix polysaccharides, a gelled network of pectins ionically linked by calcium bridges, and a network of structural proteins covalently cross-linked to one another and perhaps to other elements in the wall matrix (Talbott and Ray, 1992a; Carpita and Gibeaut, 1993).In muro, these networks probably interact with one another in many ways and may not be as separable as implied in this description.At least one of these networks must bear the mechanical stresses in the wall, yet surprisingly little is known about the distribution of stresses among these wall components in growing cells.Biophysical and biochemical analyses of cell walls point to the matrix as being most significant for governing the growth properties of walls.Recent work on cells with modified walls has shown that walls can be modified to a remarkable degree and still maintain structural integrity (Shedletzky et al., 1992).Evidently, plant cells can adapt to a wide range of wall structures and still function well enough to survive and grow slowly in cultures.Such adaptability and developmental plasticity suggest that plant cells possess more than one mechanism for extending their walls.This article briefly summarizes recent work that identifies '
Source: PLANT PHYSIOLOGY
DOI: 10.1104/pp.102.1.1
Author: D. J. Cosgrove
Institution: Pennsylvania State University
Language: English
Subfield: Plant Science
Domain: Life Sciences
Open Access status: bronze
Funder: National Science Foundation
OpenAlex ID: W1989358436