Growth control by cell wall pectins

Abstract

Plant cell growth is controlled by the balance between turgor pressure and the extensibility of the cell wall. Several distinct classes of wall polysaccharides and their interactions contribute to the architecture and the emergent features of the wall. As a result, remarkable tensile strength is achieved without relinquishing extensibility. The control of growth and development does not only require a precisely regulated biosynthesis of cell wall components, but also constant remodeling and modification after deposition of the polymers. This is especially evident given the fact that wall deposition and cell expansion are largely uncoupled. Pectins form a functionally and structurally diverse class of galacturonic acid-rich polysaccharides which can undergo abundant modification with a concomitant change in physicochemical properties. This review focuses on homogalacturonan demethylesterification catalyzed by the ubiquitous enzyme pectin methylesterase (PME) as a growth control module. Special attention is drawn to the recently discovered role of this process in primordial development in the shoot apical meristem.

KNS4/UPEX1: A Type II Arabinogalactan β-(1,3)-Galactosyltransferase Required for Pollen Exine Development

“…2). It has been proposed that pectin plays an important role in both cell adhesion and cell separation in plant organ development (Micheli, 2001;Pelloux et al, 2007;Wolf and Greiner, 2012). We detected differences between wild type and kns4 both in the deposition of AGPs (Figs.…”

Monitoring Polysaccharide Dynamics in the Plant Cell Wall

“…The orientation of microfibrils is hypothesized to mechanically restrict the direction of cell extension, leading to anisotropic growth. Parallel cellulose microfibrils are separated during cell expansion (Marga et al, 2005), presumably yielding to internal turgor pressure and being loosened via the enzymatic modification of adjoining matrix polysaccharides (Wolf and Greiner, 2012;Cosgrove, 2016). Since microfibril diameters do not appear to decrease during the elongation process, the fibrils likely are not modified directly.…”

Homogenization of Biomechanical Models for Plant Tissues

“…In cell walls and middle lamella, pectin can be modified by the enzyme pectin methylesterase (PME), which removes methyl groups by breaking ester bonds. The de-esterified pectin is able to form calcium-pectin cross-links, and thus stiffen the cell wall and reduce its expansion; see, e.g., [50]. On the other hand, mechanical stresses can break calcium-pectin crosslinks and hence increase the extensibility of plant cell walls and middle lamella.…”

“…On the other hand, mechanical stresses can break calcium-pectin crosslinks and hence increase the extensibility of plant cell walls and middle lamella. It has been shown that chemical properties of pectin and the control of the density of calcium-pectin cross-links greatly influence the mechanical deformations of plant cell walls [34], and the interference with PME activity causes dramatic changes in growth behavior of plant tissues [50].…”

“…Pectin is deposited into the cell wall in a highly methylesterified state and is modified by the wall enzyme PME, which removes methyl groups [50]. It was observed experimentally that pectins can diffuse in a plant cell wall matrix; see, e.g., [18,35,48].…”