Biography
As a PhD student working with Véronique Pautot (INRA, Versailles) and Gerrit Beemster (VIB, Ghent, Belgium), he studied the regulation of meristem function by a set of highly conserved transcription factors in Arabidopsis. He notably showed a role of the gaseous hormone ethylene in regulating the function of homeodomain proteins. He then moved to a completely different field, meiosis in maize, with the group of Zac Cande at UC Berkeley (USA), where he identified and characterized the first plant shugoshin, a protein controlling chromosome segregation.
After this, he moved to Lyon (France), where he started his current work on the role of mechanical signals in plant morphogenesis, bridging molecular and cellular biology with modeling and biophysics, notably through visits to SLCU from 2011 onwards. He received a number of awards, including “laurier jeune chercheur” from INRA and the Paul Doisteau - Emile Blutet prize from the French science academy. He now holds a research director position at the Plant Reproduction and Development lab (Lyon) and continues fruitful collaborations at SLCU with Elliot Meyerowitz, Ray Wightman and Henrik Jönsson.
Research
Development relies on a complex network of molecular effectors that ultimately modify the mechanical properties of cells and control shape changes. In turn, mechanical forces can also exert a feedback on the molecular network to channel development. Several mechanosensitive proteins have been identified in animals but their role in multicellular development remains poorly documented. Plants are ideal systems to study mechanotransduction in development because their mechanics are mainly mediated by the cell wall. We have already characterized the response of microtubules to mechanical stress using a set of micromechanical tools (e.g. Hamant et al., 2008 Science, Uyttewaal et al., 2012 Cell) and we are now exploring the many implications of these mechanical feedbacks in the robustness of shape changes in plants (e.g. Landrein et al., 2015; Hervieux et al., 2016). In parallel, we have started to explore how these mechanical signals are transduced molecularly, thus formally integrating the role of mechanotransduction in plant development, with a focus on the shoot apical meristem.
Publications
Hervieux N, Dumond M, Sapala A, Routier-Kierzkowska AL, Kierzkowski D, Roeder AH, Smith RS, Boudaoud A, Hamant O. (2016) A Mechanical Feedback Restricts Sepal Growth and Shape in Arabidopsis. Curr Biol. 26, 1019–1028
Landrein B, Kiss A, Sassi M, Chauvet A, Das P, Cortizo M, Laufs P, Takeda S, Aida M, Traas J, Vernoux T, Boudaoud A, Hamant O. (2015) Mechanical stress contributes to the expression of the STM homeobox gene in Arabidopsis shoot meristems. Elife. 4:e07811.
Uyttewaal M,Burian A, Alim K, Landrein B, Borowska-Wykręt D, Dedieu A, Peaucelle A, Ludynia M, Traas J, Boudaoud A, Kwiatkowska D, Hamant O
(2012) A katanin-dependent microtubule response to mechanical stress enhances growth gradients between neighboring cells in Arabidopsis. Cell 149 (2): 439-451.
Key Publications with SLCU
Gruel J, Landrein B, Tarr P, Schuster C, Refahi Y, Sampathkumar A, Hamant O, Meyerowitz EM, Jönsson H. (2016) An epidermis-driven mechanism positions and scales stem cell niches in plants. Sci Adv. 2(1):e1500989.
Sampathkumar A, Krupinski P, Wightman R, Milani P, Berquand A, Boudaoud A, Hamant O, Jönsson H, Meyerowitz EM. (2014) Subcellular and supracellular mechanical stress prescribes cytoskeleton behavior in Arabidopsis cotyledon pavement cells. eLife. 3:e01967.
Selected Reviews
Asnacios A, Hamant O (2012) The mechanics behind cell polarity. Trends Cell Biol. 22(11): 584-91
Hamant O (2013) Widespread mechanosensing controls the structure behind the architecture in plants. Curr Opin Plant Biol. 16(5):654-60
