Pectin Methylesterase Function in Plant Growth and Development

Pectin methylesterases (PMEs) are a class of cell-wall remodelling enzymes that catalyse the removal of methyl groups from homogalacturonan domains of pectin, a major structural polysaccharide. By altering the degree and pattern of methylesterification, PMEs influence the mechanical properties of the cell wall, including porosity, elasticity and adhesion between cells. This fine-tuning of cell-wall architecture underpins key developmental processes such as cell expansion, seed germination, pollen tube growth and organ abscission. PME activity is dynamically regulated by pectin methylesterase inhibitors (PMEIs), which bind to PMEs and modulate their processivity in a pH-dependent manner. Together, the interplay between PMEs and PMEIs governs the release of apoplastic calcium, dictates cell-wall stiffening or loosening and contributes to cell-to-cell signalling. Beyond growth and morphogenesis, PME-mediated demethylesterification generates oligogalacturonides that act as damage-associated molecular patterns in pathogen defence and as mediators of tolerance to abiotic stress. Harnessing PME function has practical implications for crop improvement, including grain-size optimisation, enhanced stress resilience and the tailoring of fruit texture for post-harvest quality.

Research from Nature Portfolio

Recent work has elucidated a pollen-expressed PME gene at a maize reproductive barrier locus that confers male function in unilateral cross-incompatibility. Transgenic expression of this PME in pollen restores fertilisation capacity in otherwise incompatible silks, revealing that PME-mediated maintenance of a precise pectin methylesterification state at the pollen tube apex is essential for successful tube growth. Interaction with a secondary pollen PME ensures correct patterning of demethylesterified pectin stretches, thereby controlling the biomechanics of pollen tube penetration in the style.

Pectin Methylesterase Function in Plant Growth and Development publication trend

The graph below shows the total number of articles in pectin methylesterase function in plant growth and development across all publications each year (not limited to Nature Index journals).

Technical terms

Pectin Methylesterase (PME): An enzyme that removes methyl esters from homogalacturonan pectin chains, affecting cell-wall rigidity and porosity.

Homogalacturonan (HG): A linear polymer of galacturonic acid units in pectin that is methylesterified during synthesis and demethylesterified by PMEs.

Pectin Methylesterase Inhibitor (PMEI): A small protein that binds to PMEs, regulating their activity and modulation of the pectin methylesterification pattern.

Degree of Methylesterification (DM): The proportion of galacturonic acid residues in HG that remain methylesterified; a key determinant of cell-wall mechanical properties.

Cell-Wall Porosity: The effective pore size within the cell-wall matrix, influenced by pectin methylesterification and critical for solute movement and cell expansion.

References

1. Ovule cell wall composition is a maternal determinant of grain size in barley. New Phytologist (2023).
2. Pectin Methylesterases: Cell Wall Remodeling Proteins Are Required for Plant Response to Heat Stress. Frontiers in Plant Science (2018).
3. Demethylesterification of Cell Wall Pectins in Arabidopsis Plays a Role in Seed Germination. Plant Physiology (2012).
4. PECTIN METHYLESTERASE48 Is Involved in Arabidopsis Pollen Grain Germination. Plant Physiology (2014).
5. A PECTIN METHYLESTERASE gene at the maize Ga1 locus confers male function in unilateral cross-incompatibility. Nature Communications (2018).
6. Tuning of Pectin Methylesterification PECTIN METHYLESTERASE INHIBITOR 7 MODULATES THE PROCESSIVE ACTIVITY OF CO-EXPRESSED PECTIN METHYLESTERASE 3 IN A pH-DEPENDENT MANNER*. Journal of Biological Chemistry (2015).