Advances in the functional research of pectin methylesterases in Arabidopsis thaliana.

Pectin methylesterases (PMEs) are key enzymes that regulate the structure and function of pectin in plant cell walls. By fine-tuning the degree and pattern of homogalacturonan (HG) de-methylesterification, PMEs profoundly influence cell wall mechanics and associated signaling processes. In recent years, substantial progress has been made in elucidating the functions of the PME gene family, and much of the current understanding of PME activity and regulation has been derived from studies in Arabidopsis thaliana. Accumulating evidence indicates that individual PME members play highly specialized roles in plant growth and development, including cell elongation, organ morphogenesis, pollen tube growth, and seed development. In addition, PME-mediated pectin remodeling is closely linked not only to plant immune responses against pathogen invasion, but also to cell wall integrity sensing and signal control, thereby influencing pathogen perception and downstream defense responses. Under abiotic stress and climate change-related environmental challenges, the dynamic interplay between PMEs and pectin methylesterase inhibitors (PMEIs) is essential for plant adaptation to salinity, drought, temperature extremes, and heavy metal stress, while maintaining the cell wall as a highly dynamic, plastic, and tightly regulated structure. With advances in molecular genetics, multi-omics approaches, and high-resolution imaging technologies, the spatiotemporal regulatory networks and mechanistic basis of PME/PMEI function are being progressively uncovered. Together, these insights underscore the central importance of PMEs in cell wall biology, plant adaptive responses, and crop improvement.