Relating the mechanics of the primary plant cell wall to morphogenesis

Abstract

Regulation of the mechanical properties of the cell wall is a key parameter used by plants to control the growth behavior of individual cells and tissues. Modulation of the mechanical properties occurs through the control of the biochemical composition and the degree and nature of interlinking between cell wall polysaccharides. Preferentially oriented cellulose microfibrils restrict cellular expansive growth, but recent evidence suggests that this may not be the trigger for anisotropic growth. Instead, non-uniform softening through the modulation of pectin chemistry may be an initial step that precedes stress-induced stiffening of the wall through cellulose. Here we briefly review the major cell wall polysaccharides and their implication for plant cell wall mechanics that need to be considered in order to study the growth behavior of the primary plant cell wall.

Branched Pectic Galactan in Phloem-Sieve-Element Cell Walls: Implications for Cell Mechanics

“…In Muro Testing of Cell Wall Nanomechanics of Nondermal Cells AFM-based techniques in plant biology have allowed the direct testing of cell wall mechanics on a submuro, cellular, and tissue level (Cosgrove 2016;Bidhendi and Geitmann 2016;Carter et al, 2017). Technically, to-date, analyses of developing plant systems have been limited to readily accessible unadhered cells and surface cell walls of epidermal tissues, with internal tissue mechanics only being inferred by large-scale indentations through multiple cell layers (Peaucelle et al, 2011).…”

Finite Element Modeling of Shape Changes in Plant Cells

“…While this is a reasonable hypothesis (Bidhendi and Geitmann, 2016), the study provides no evidence for the fact that the weakly esterified pectin was gelated by calcium or whether the mechanical properties of the cell wall materials were altered in any way. The antibody 2F4 was not used on the mutant, let alone micromechanical testing of cell wall properties.…”

“…This would entail an initial turgor-induced change in geometry from elliptical to circular (inflation), followed by an accommodation of any further increase in pressure by cell wall stretching, a process that requires higher turgor differentials to produce visible results. Therefore, the matrix strain-stiffening conjecture proffered by Woolfenden et al (2017), while consistent with polymer chemistry (Bidhendi and Geitmann, 2016), could be a secondary mechanism responsible for the apparent low sensitivity of aperture opening at high pressures. These concepts certainly merit further validation.…”

A Distinct Pathway for Polar Exocytosis in Plant Cell Wall Formation

“…Previous studies indicate that NtPPME1 plays essential roles in pollen tube apical cell wall formation by determining its rigidity via demethylesterification of pectins (Bosch et al, 2005;Fayant et al, 2010;Chebli et al, 2012;Wang et al, 2013;Bidhendi and Geitmann, 2016). However, the subcellular localization and polar exocytosis of NtPPME1 remains unexplored.…”

“…They also should be strong enough to withstand the internal turgor pressure and thereby maintain the shape of the cell (Zonia and Munnik, 2011;Hepler et al, 2013). Recent studies have demonstrated that pectins are important for both cytokinesis and cell expansion (Moore and Staehelin, 1988;Bosch et al, 2005;Chebli et al, 2012;Altartouri and Geitmann, 2015;Bidhendi and Geitmann, 2016). Pectins are one of the major cell wall components of the middle lamella and primary cell wall.…”