article published yes Maciek Adamowski author 45F536D2-F248-11E8-B48F-1D18A9856A870000-0001-6463-5257 Lanxin Li author 367EF8FA-F248-11E8-B48F-1D18A9856A870000-0002-5607-272X Jiří Friml author 4159519E-F248-11E8-B48F-1D18A9856A870000-0002-8302-7596 JiFr department Polarity and subcellular dynamics in plants project International IST Doctoral Program project IST Austria Open Access Fund project Cortical microtubule arrays in elongating epidermal cells in both the root and stem of plants have the propensity of dynamic reorientations that are correlated with the activation or inhibition of growth. Factors regulating plant growth, among them the hormone auxin, have been recognized as regulators of microtubule array orientations. Some previous work in the field has aimed at elucidating the causal relationship between cell growth, the signaling of auxin or other growth-regulating factors, and microtubule array reorientations, with various conclusions. Here, we revisit this problem of causality with a comprehensive set of experiments in Arabidopsis thaliana, using the now available pharmacological and genetic tools. We use isolated, auxin-depleted hypocotyls, an experimental system allowing for full control of both growth and auxin signaling. We demonstrate that reorientation of microtubules is not directly triggered by an auxin signal during growth activation. Instead, reorientation is triggered by the activation of the growth process itself and is auxin-independent in its nature. We discuss these findings in the context of previous relevant work, including that on the mechanical regulation of microtubule array orientation. https://research-explorer.ista.ac.at/download/6627/6645/2019_JournalMolecularScience_Adamowski.pdf application/pdfno MDPI2019 eng 1422-0067 31284661 00047704110022110.3390/ijms20133337 2013 https://research-explorer.ista.ac.at/record/10083 Adamowski M, Li L, Friml J. Reorientation of cortical microtubule arrays in the hypocotyl of arabidopsis thaliana is induced by the cell growth process and independent of auxin signaling. <i>International Journal of Molecular Sciences</i>. 2019;20(13). doi:<a href="https://doi.org/10.3390/ijms20133337">10.3390/ijms20133337</a> Adamowski, M., Li, L., &#38; Friml, J. (2019). Reorientation of cortical microtubule arrays in the hypocotyl of arabidopsis thaliana is induced by the cell growth process and independent of auxin signaling. <i>International Journal of Molecular Sciences</i>. MDPI. <a href="https://doi.org/10.3390/ijms20133337">https://doi.org/10.3390/ijms20133337</a> Adamowski, Maciek, Lanxin Li, and Jiří Friml. “Reorientation of Cortical Microtubule Arrays in the Hypocotyl of Arabidopsis Thaliana Is Induced by the Cell Growth Process and Independent of Auxin Signaling.” <i>International Journal of Molecular Sciences</i>. MDPI, 2019. <a href="https://doi.org/10.3390/ijms20133337">https://doi.org/10.3390/ijms20133337</a>. Adamowski, Maciek, et al. “Reorientation of Cortical Microtubule Arrays in the Hypocotyl of Arabidopsis Thaliana Is Induced by the Cell Growth Process and Independent of Auxin Signaling.” <i>International Journal of Molecular Sciences</i>, vol. 20, no. 13, 3337, MDPI, 2019, doi:<a href="https://doi.org/10.3390/ijms20133337">10.3390/ijms20133337</a>. Adamowski M, Li L, Friml J. 2019. Reorientation of cortical microtubule arrays in the hypocotyl of arabidopsis thaliana is induced by the cell growth process and independent of auxin signaling. International Journal of Molecular Sciences. 20(13), 3337. M. Adamowski, L. Li, and J. Friml, “Reorientation of cortical microtubule arrays in the hypocotyl of arabidopsis thaliana is induced by the cell growth process and independent of auxin signaling,” <i>International Journal of Molecular Sciences</i>, vol. 20, no. 13. MDPI, 2019. M. Adamowski, L. Li, J. Friml, International Journal of Molecular Sciences 20 (2019). 66272019-07-11T12:00:32Z2026-04-16T22:33:23Z