Large Lecture Theatre
Dr Olivier Hamant
Sainsbury Laboratory, Cambridge
Studies in animal single cells have shown that mechanical cues can affect important cell processes such as cell polarity, cell fate or cell division. Here we take advantage of the simpler plant mechanics to investigate this question in a tissue context. Using confocal live imaging, micromechanics and modeling, we found that mechanical signals control the orientation of cortical microtubules, which guide the deposition of cellulose and thus control the mechanical anisotropy of plant cell walls. This in turn supports multicellular morphogenetic events, such as tissue folding, which further consolidates the stress pattern. Interestingly, and depending on stress magnitude, this mechanical feedback loop may also add robustness to individual cell shapes. We also found that this mechanical feedback loop promotes growth heterogeneity in tissues. We propose that the maintenance of a basal level of growth heterogeneity potentiates organogenesis. Conversely, this raises the question of the role of growth heterogeneity in the formation of organs with consistent shapes, and the contribution of mechanical signals in this process. More recently, we started to analyze the contribution of mechanical signals in controlling gene expression patterns and cell fate within the meristem, the plant stem cell niche.