The shoot apical meristem of plants is responsible for the upward growth of the plant. This small group of stem cells also leads to lateral branches and to flowering structures. Hamant et al. (see the Perspective by Mulder) analyzed the forces patterning the microtubule network, which seems to guide development of the cell wall. The microtubule network and the signaling by the plant hormone auxin both affect how the shoot apical meristem functions. Theoretical calculations of stresses in the meristem and during primordium outgrowth paralleled the pattern of microtubules. Interventions involving ablation of individual cells to change the stress pattern confirmed that microtubule networks generally follow the pattern of physical stresses imposed on the cells.
O. Hamant, M. G. Heisler, H. Jönsson, P. Krupinski, M. Uyttewaal, P. Bokov, F. Corson, P. Sahlin, A. Boudaoud, E. M. Meyerowitz, Y. Couder, J. Traas, Developmental patterning by mechanical signals in Arabidopsis. Science 322, 1650–1655 (2008). [Abstract] [Full Text]