article published yes Marçal Gallemi author 460C6802-F248-11E8-B48F-1D18A9856A870000-0003-4675-6893 Juan C Montesinos López author 310A8E3E-F248-11E8-B48F-1D18A9856A870000-0001-9179-6099 Nikola Zarevski author 18e95355-e05a-11ea-a9c0-8fba1b89e83a Jan Pribyl author Petr Skládal author Edouard B Hannezo author 3A9DB764-F248-11E8-B48F-1D18A9856A870000-0001-6005-1561 Eva Benková author 38F4F166-F248-11E8-B48F-1D18A9856A870000-0002-8510-9739 EdHa department EvBe department CaGu department Hormonal cross-talk in plant organogenesis project IST Austria Open Access Fund project Introduction: Acid-growth theory has been postulated in the 70s to explain the rapid elongation of plant cells in response to the hormone auxin. More recently, it has been demonstrated that activation of the proton ATPs pump (H+-ATPs) promoting acidification of the apoplast is the principal mechanism by which auxin and other hormones such as brassinosteroids (BR) induce cell elongation. Despite these advances, the impact of this acidification on the mechanical properties of the cell wall remained largely unexplored. Methods: Here, we use elongation assays of Arabidopsis thaliana hypocotyls and Atomic Force Microscopy (AFM) to correlate hormone-induced tissue elongation and local changes in cell wall mechanical properties. Furthermore, employing transgenic lines over-expressing Pectin Methyl Esterase (PME), along with calcium chelators, we investigate the effect of pectin modification in hormone-driven cell elongation. Results: We demonstrate that acidification of apoplast is necessary and sufficient to induce cell elongation through promoting cell wall softening. Moreover, we show that enhanced PME activity can induce both cell wall softening or stiffening in extracellular calcium dependent-manner and that tight control of PME activity is required for proper hypocotyl elongation. Discussion: Our results confirm a dual role of PME in plant cell elongation. However, further investigation is needed to assess the status of pectin following short- or long-term PME treatments in order to determine if pectin methyl-esterification might promote its degradation as well as the role of PME inhibitors upon PME induction. https://research-explorer.ista.ac.at/download/20080/20093/2025_FrontiersPlantSc_Gallemi.pdf application/pdfno Frontiers Media2025 eng 1664-462X 40688689 00153069090000110.3389/fpls.2025.1612366 16 Gallemi, Marçal, Juan C Montesinos López, Nikola Zarevski, Jan Pribyl, Petr Skládal, Edouard B Hannezo, and Eva Benková. “Dual Role of Pectin Methyl Esterase Activity in the Regulation of Plant Cell Wall Biophysical Properties.” <i>Frontiers in Plant Science</i>. Frontiers Media, 2025. <a href="https://doi.org/10.3389/fpls.2025.1612366">https://doi.org/10.3389/fpls.2025.1612366</a>. Gallemi, M., Montesinos López, J. C., Zarevski, N., Pribyl, J., Skládal, P., Hannezo, E. B., &#38; Benková, E. (2025). Dual role of pectin methyl esterase activity in the regulation of plant cell wall biophysical properties. <i>Frontiers in Plant Science</i>. Frontiers Media. <a href="https://doi.org/10.3389/fpls.2025.1612366">https://doi.org/10.3389/fpls.2025.1612366</a> Gallemi, Marçal, et al. “Dual Role of Pectin Methyl Esterase Activity in the Regulation of Plant Cell Wall Biophysical Properties.” <i>Frontiers in Plant Science</i>, vol. 16, 1612366, Frontiers Media, 2025, doi:<a href="https://doi.org/10.3389/fpls.2025.1612366">10.3389/fpls.2025.1612366</a>. M. Gallemi <i>et al.</i>, “Dual role of pectin methyl esterase activity in the regulation of plant cell wall biophysical properties,” <i>Frontiers in Plant Science</i>, vol. 16. Frontiers Media, 2025. M. Gallemi, J.C. Montesinos López, N. Zarevski, J. Pribyl, P. Skládal, E.B. Hannezo, E. Benková, Frontiers in Plant Science 16 (2025). Gallemi M, Montesinos López JC, Zarevski N, Pribyl J, Skládal P, Hannezo EB, Benková E. 2025. Dual role of pectin methyl esterase activity in the regulation of plant cell wall biophysical properties. Frontiers in Plant Science. 16, 1612366. Gallemi M, Montesinos López JC, Zarevski N, et al. Dual role of pectin methyl esterase activity in the regulation of plant cell wall biophysical properties. <i>Frontiers in Plant Science</i>. 2025;16. doi:<a href="https://doi.org/10.3389/fpls.2025.1612366">10.3389/fpls.2025.1612366</a> 200802025-07-27T22:01:26Z2026-05-20T07:53:03Z