An auxin-mediated shift toward growth isotropy promotes organ formation at the shoot meristem in Arabidopsis

article An auxin-mediated shift toward growth isotropy promotes organ formation at the shoot meristem in Arabidopsis published yes Massimiliano Sassi author Olivier Ali author Frédéric Boudon author Gladys Cloarec author Ursula Abad author Coralie Cellier author Xu Chen author 4E5ADCAA-F248-11E8-B48F-1D18A9856A87 Benjamin Gilles author Pascale Milani author Jirí Friml author 4159519E-F248-11E8-B48F-1D18A9856A870000-0002-8302-7596 Teva Vernoux author Christophe Godin author Olivier Hamant author Jan Traas author JiFr department To control morphogenesis, molecular regulatory networks have to interfere with the mechanical properties of the individual cells of developing organs and tissues, but how this is achieved is not well known. We study this issue here in the shoot meristem of higher plants, a group of undifferentiated cells where complex changes in growth rates and directions lead to the continuous formation of new organs [1, 2]. Here, we show that the plant hormone auxin plays an important role in this process via a dual, local effect on the extracellular matrix, the cell wall, which determines cell shape. Our study reveals that auxin not only causes a limited reduction in wall stiffness but also directly interferes with wall anisotropy via the regulation of cortical microtubule dynamics. We further show that to induce growth isotropy and organ outgrowth, auxin somehow interferes with the cortical microtubule-ordering activity of a network of proteins, including AUXIN BINDING PROTEIN 1 and KATANIN 1. Numerical simulations further indicate that the induced isotropy is sufficient to amplify the effects of the relatively minor changes in wall stiffness to promote organogenesis and the establishment of new growth axes in a robust manner. Cell Press2014 eng Current Biology 00034274760003110.1016/j.cub.2014.08.036 24192335 - 2342 Sassi, Massimiliano, Olivier Ali, Frédéric Boudon, Gladys Cloarec, Ursula Abad, Coralie Cellier, Xu Chen, et al. “An Auxin-Mediated Shift toward Growth Isotropy Promotes Organ Formation at the Shoot Meristem in Arabidopsis.” Current Biology. Cell Press, 2014. <a href="https://doi.org/10.1016/j.cub.2014.08.036">https://doi.org/10.1016/j.cub.2014.08.036</a>. Sassi, Massimiliano, et al. “An Auxin-Mediated Shift toward Growth Isotropy Promotes Organ Formation at the Shoot Meristem in Arabidopsis.” Current Biology, vol. 24, no. 19, Cell Press, 2014, pp. 2335–42, doi:<a href="https://doi.org/10.1016/j.cub.2014.08.036">10.1016/j.cub.2014.08.036</a>. Sassi M, Ali O, Boudon F, Cloarec G, Abad U, Cellier C, Chen X, Gilles B, Milani P, Friml J, Vernoux T, Godin C, Hamant O, Traas J. 2014. An auxin-mediated shift toward growth isotropy promotes organ formation at the shoot meristem in Arabidopsis. Current Biology. 24(19), 2335–2342. Sassi, M., Ali, O., Boudon, F., Cloarec, G., Abad, U., Cellier, C., … Traas, J. (2014). An auxin-mediated shift toward growth isotropy promotes organ formation at the shoot meristem in Arabidopsis. Current Biology. Cell Press. <a href="https://doi.org/10.1016/j.cub.2014.08.036">https://doi.org/10.1016/j.cub.2014.08.036</a> M. Sassi, O. Ali, F. Boudon, G. Cloarec, U. Abad, C. Cellier, X. Chen, B. Gilles, P. Milani, J. Friml, T. Vernoux, C. Godin, O. Hamant, J. Traas, Current Biology 24 (2014) 2335–2342. Sassi M, Ali O, Boudon F, et al. An auxin-mediated shift toward growth isotropy promotes organ formation at the shoot meristem in Arabidopsis. Current Biology. 2014;24(19):2335-2342. doi:<a href="https://doi.org/10.1016/j.cub.2014.08.036">10.1016/j.cub.2014.08.036</a> M. Sassi et al., “An auxin-mediated shift toward growth isotropy promotes organ formation at the shoot meristem in Arabidopsis,” Current Biology, vol. 24, no. 19. Cell Press, pp. 2335–2342, 2014. 18522018-12-11T11:54:22Z2025-09-29T13:10:45Z