Pectin methylesterases as strategic modulators of plant–environment interactions

The plant cell wall is a dynamic and highly regulated structure that plays a pivotal role in plant growth, development, and adaptation to environmental stress. Among the key cell wall–modifying enzymes, pectin methylesterases (PMEs) control the methylesterification status of homogalacturonan, affecting wall properties and cell signaling (Lionetti 2015; Lionetti et al. 2017). Although PME activity has been linked to stress responses (Coculo et al. 2023), the specific functions of individual isoforms are still not fully understood. This study analyzed PME gene expression in Arabidopsis thaliana under various environmental stress conditions, including thermal, water-related, and salt-related treatments, and in response to biotic stresses. Our results revealed the involvement of PME isoforms in specific plant’s response to environmental cues. Intriguingly, PME isoforms reached the cell wall through distinct secretory routes, ranging from conventional or unconventional pathways. This diversity in secretion mechanisms may influence the localization and timing of PME activity, thereby affecting the plant's capacity to remodel its cell wall under stress. PME-mediated cell wall remodeling in plant responses to diverse environmental stresses will be discussed.