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

Author(s): Sassi, Massimiliano; Ali, Olivier; Boudon, Frédéric; Cloarec, Gladys; Abad, Ursula; Cellier, Coralie; Chen, Xu; Gilles, Benjamin; Milani, Pascale; Friml, Jiří; Vernoux, Teva; Godin, Christophe; Hamant, Olivier; Traas, Jan A
Article Title: An auxin-mediated shift toward growth isotropy promotes organ formation at the shoot meristem in Arabidopsis
Affiliation IST Austria
Abstract: 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.
Journal Title: Current Biology
Volume: 24
Issue 9
ISSN: 0960-9822
Publisher: Cell Press  
Date Published: 2014-10-06
Start Page: 2335
End Page: 2342
Sponsor: This work was funded by grants from EraSysBio+ (iSAM) and ERC (Morphodynamics).
DOI: 10.1016/j.cub.2014.08.036
Notes: We thank Dolf Weijers (Wageningen University) and Zhenbiao Yang (Riverside University) for generously providing seeds. We thank all the member of the J.T. laboratory for helpful discussions and Arezki Boudaoud and Roberta Galletti for helpful discussions and critical reading of the manuscript.
Open access: yes (repository)