Thursday 26 January 2017
The interplay between global and local rules regulates multicellular morphogenesis
University of Birmingham UK
Multicellular organ development is driven by the combination of the division and expansion of cells, and the mechanical interactions between their neighbours. In plants, cells are immobilized through shared cell walls, and patterns emerge through the regulated placement of division planes. Rules following local cell geometry have been devised to predict where cells will divide, and it is proposed that the iterative repetition of these rules leads to the emergent cellular organization present within organs. While these local rules have been examined previously, it remains unknown whether global regulatory mechanisms also act to co-ordinate the organization of complex multicellular configurations. We explored this possibility by performing 4D imaging of each the tomato and Arabidopsis shoot apical meristems (SAM), and topologically analysing their intercellular connectivity using network science. This enabled the properties of cellular patterning and the outputs of the self-organizing process to be quantified. Using this approach, a previously undescribed global property of global cellular organization in the SAM was uncovered. Further analyses of these networks has provided compelling evidence for the presence of a global mobile signal that mediates the organization of cell across the shoot apex. These results indicate the presence of a higher-order regulatory mechanism which feeds down onto local rules within individual cells.
Contact : Benoît Lacombe