Abstract text: Pectin methylesterases (PMEs) are major regulators of plant cell wall dynamics. By modulating the methylesterification pattern of homogalacturonan, PMEs control key physicochemical properties of the wall, including stiffness, porosity, and the formation of calcium-mediated pectin crosslinks (Lionetti et al., 2012; Pecatelli et al., 2026). Tight regulation of PME activity is therefore essential for the spatial and temporal control of pectin remodeling. One important regulatory mechanism involves the proteolytic activation of inactive pro-PMEs by subtilases (SBTs) within the secretory pathway (Coculo et al., 2023). However, how PME and SBT trafficking, secretion, and activation are coordinated remains largely unknown. Here, we investigate the secretion routes, subcellular targeting, and post-translational regulation of selected Arabidopsis PMEs and SBTs. Our findings reveal distinct trafficking pathways and regulatory steps that control PME maturation and delivery to the cell wall. These mechanisms provide a framework for understanding how protease-mediated activation and secretory dynamics contribute to the fine spatial control of pectin modification and, ultimately, to the regulation of cell wall architecture and plasticity.

Lionetti, V., et al 2012, Journal of Plant Physiology, 169:1623-30.

Coculo, D., et al 2023, Plant Physiology and Biochemistry, 201:107865

Pecatelli G. et al 2026, Plant Communication, in Press