Limits...
Cell wall mechanics and growth control in plants: the role of pectins revisited.

Peaucelle A, Braybrook S, Höfte H - Front Plant Sci (2012)

Bottom Line: How is the extensibility of growing plant cell walls regulated?In the past, most studies have focused on the role of the cellulose/xyloglucan network and the enigmatic wall-loosening agents expansins.Here we review first how in the closest relatives of the land plants, the Charophycean algae, cell wall synthesis is coupled to cell wall extensibility by a chemical Ca(2+)-exchange mechanism between Ca(2+)-pectate complexes.

View Article: PubMed Central - PubMed

Affiliation: Institut Jean-Pierre Bourgin, UMR1318 INRA/AgroParisTech, Saclay Plant Sciences, INRA Centre de Versailles, Versailles, France.

ABSTRACT
How is the extensibility of growing plant cell walls regulated? In the past, most studies have focused on the role of the cellulose/xyloglucan network and the enigmatic wall-loosening agents expansins. Here we review first how in the closest relatives of the land plants, the Charophycean algae, cell wall synthesis is coupled to cell wall extensibility by a chemical Ca(2+)-exchange mechanism between Ca(2+)-pectate complexes. We next discuss evidence for the existence in terrestrial plants of a similar "primitive" Ca(2+)-pectate-based growth control mechanism in parallel to the more recent, land plant-specific, expansin-dependent process.

No MeSH data available.


Chemorheological control of wall extensibility.(A) Principle: microfibrils (brown), which in most cases form parallel arrays, are cross-linked by load-bearing (violet) and relaxed (light blue) bonds. The number and strength of the load-bearing bonds determines cell wall strength. Wall extensibility is controlled by chemorheological mechanisms that remove load-bearing bonds. The cell wall relaxes and undergoes turgor-driven mechanical deformation until previously relaxed bonds become load-bearing. (B) Cartoon of cell wall architecture showing microfibrils (brown) and XG chains (green). A small portion of the XG is intertwined or complexed with cellulose, thus sticking the microfibrils together at these points. The endoglucanase Cel12A as well as expansin may act on these relatively inaccessible XG–cellulose interaction domains.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC3368173&req=5

Figure 1: Chemorheological control of wall extensibility.(A) Principle: microfibrils (brown), which in most cases form parallel arrays, are cross-linked by load-bearing (violet) and relaxed (light blue) bonds. The number and strength of the load-bearing bonds determines cell wall strength. Wall extensibility is controlled by chemorheological mechanisms that remove load-bearing bonds. The cell wall relaxes and undergoes turgor-driven mechanical deformation until previously relaxed bonds become load-bearing. (B) Cartoon of cell wall architecture showing microfibrils (brown) and XG chains (green). A small portion of the XG is intertwined or complexed with cellulose, thus sticking the microfibrils together at these points. The endoglucanase Cel12A as well as expansin may act on these relatively inaccessible XG–cellulose interaction domains.

Mentions: Plant cell growth reflects the balance between the extensibility of the cell wall and the forces exerted on the wall by the turgor pressure. Although growth in principle can be controlled by changing either parameter, in most documented cases growth changes reflect changes in cell wall extensibility (Cosgrove, 2005). The paradoxical properties of cell walls, which combine extensibility with extreme strength, can be easily understood by keeping in mind that wall strength is determined by the number and strength of load-bearing bonds and by assuming that a wall relaxation mechanism exists that can break these bonds and transfer the load to new bonds (Figure 1). Wall relaxation and cell expansion can occur, in principle, with or without a change in wall strength, depending on whether or not this chemorheological process causes a net change in the number or strength of the load-bearing bonds.


Cell wall mechanics and growth control in plants: the role of pectins revisited.

Peaucelle A, Braybrook S, Höfte H - Front Plant Sci (2012)

Chemorheological control of wall extensibility.(A) Principle: microfibrils (brown), which in most cases form parallel arrays, are cross-linked by load-bearing (violet) and relaxed (light blue) bonds. The number and strength of the load-bearing bonds determines cell wall strength. Wall extensibility is controlled by chemorheological mechanisms that remove load-bearing bonds. The cell wall relaxes and undergoes turgor-driven mechanical deformation until previously relaxed bonds become load-bearing. (B) Cartoon of cell wall architecture showing microfibrils (brown) and XG chains (green). A small portion of the XG is intertwined or complexed with cellulose, thus sticking the microfibrils together at these points. The endoglucanase Cel12A as well as expansin may act on these relatively inaccessible XG–cellulose interaction domains.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3368173&req=5

Figure 1: Chemorheological control of wall extensibility.(A) Principle: microfibrils (brown), which in most cases form parallel arrays, are cross-linked by load-bearing (violet) and relaxed (light blue) bonds. The number and strength of the load-bearing bonds determines cell wall strength. Wall extensibility is controlled by chemorheological mechanisms that remove load-bearing bonds. The cell wall relaxes and undergoes turgor-driven mechanical deformation until previously relaxed bonds become load-bearing. (B) Cartoon of cell wall architecture showing microfibrils (brown) and XG chains (green). A small portion of the XG is intertwined or complexed with cellulose, thus sticking the microfibrils together at these points. The endoglucanase Cel12A as well as expansin may act on these relatively inaccessible XG–cellulose interaction domains.
Mentions: Plant cell growth reflects the balance between the extensibility of the cell wall and the forces exerted on the wall by the turgor pressure. Although growth in principle can be controlled by changing either parameter, in most documented cases growth changes reflect changes in cell wall extensibility (Cosgrove, 2005). The paradoxical properties of cell walls, which combine extensibility with extreme strength, can be easily understood by keeping in mind that wall strength is determined by the number and strength of load-bearing bonds and by assuming that a wall relaxation mechanism exists that can break these bonds and transfer the load to new bonds (Figure 1). Wall relaxation and cell expansion can occur, in principle, with or without a change in wall strength, depending on whether or not this chemorheological process causes a net change in the number or strength of the load-bearing bonds.

Bottom Line: How is the extensibility of growing plant cell walls regulated?In the past, most studies have focused on the role of the cellulose/xyloglucan network and the enigmatic wall-loosening agents expansins.Here we review first how in the closest relatives of the land plants, the Charophycean algae, cell wall synthesis is coupled to cell wall extensibility by a chemical Ca(2+)-exchange mechanism between Ca(2+)-pectate complexes.

View Article: PubMed Central - PubMed

Affiliation: Institut Jean-Pierre Bourgin, UMR1318 INRA/AgroParisTech, Saclay Plant Sciences, INRA Centre de Versailles, Versailles, France.

ABSTRACT
How is the extensibility of growing plant cell walls regulated? In the past, most studies have focused on the role of the cellulose/xyloglucan network and the enigmatic wall-loosening agents expansins. Here we review first how in the closest relatives of the land plants, the Charophycean algae, cell wall synthesis is coupled to cell wall extensibility by a chemical Ca(2+)-exchange mechanism between Ca(2+)-pectate complexes. We next discuss evidence for the existence in terrestrial plants of a similar "primitive" Ca(2+)-pectate-based growth control mechanism in parallel to the more recent, land plant-specific, expansin-dependent process.

No MeSH data available.