植物的发育模式部分依赖于局部生长和定向生长。局部生长由植物生长激素调控，定向生长由细胞微管骨架管调控。加州理工学院的Marcus Heisler及其同事发现，当拟南芥细胞壁受到机械震动时，其茎尖微管的生长发育显示出胁迫模式。为验证胁迫是否影响生长素输出蛋白（PIN1）聚集，研究人员给拟南芥施加异恶草胺（isoxaben），抑制其细胞壁纤维素合成。
结果证实，机械应力影响PIN1的导向。通过数学建模，研究人员发现一个与机械信号相互作用的生长素运输系统，这个系统与活体样本中的发现类似，它可以驱动拟南芥器官的快速生长。因此在植物正常生长发育和损伤修复的过程中，机械信号的其他潜在功能值得进一步探究。
推荐英文摘要：
PLoS Biol 8(10): e1000516. doi:10.1371/journal.pbio.1000516
Alignment between PIN1 Polarity and Microtubule Orientation in the Shoot Apical Meristem Reveals a Tight Coupling between Morphogenesis and Auxin Transport
Marcus G. Heisler1#¤, Olivier Hamant2#, Pawel Krupinski3#, Magalie Uyttewaal2, Carolyn Ohno1¤, Henrik J?nsson3#*, Jan Traas2*, Elliot M. Meyerowitz1*
1 Division of Biology, California Institute of Technology, Pasadena, California, United States of America, 2 INRA, CNRS, ENS, Université de Lyon, Lyon Cedex, France, 3 Computational Biology and Biological Physics Group, Department of Theoretical Physics, Lund University, Lund, Sweden
Morphogenesis during multicellular development is regulated by intercellular signaling molecules as well as by the mechanical properties of individual cells. In particular, normal patterns of organogenesis in plants require coordination between growth direction and growth magnitude. How this is achieved remains unclear. Here we show that in Arabidopsis thaliana, auxin patterning and cellular growth are linked through a correlated pattern of auxin efflux carrier localization and cortical microtubule orientation. Our experiments reveal that both PIN1 localization and microtubule array orientation are likely to respond to a shared upstream regulator that appears to be biomechanical in nature. Lastly, through mathematical modeling we show that such a biophysical coupling could mediate the feedback loop between auxin and its transport that underlies plant phyllotaxis.
