459 / 2019-02-26 18:34:57

Cellular heterogeneity in turgor pressure and growth in the shoot apex

shoot apical meristem,turgor pressure,growth,mechanical property,physical modeling

Growth and Development > Growth and Development

Cell-to-cell fluctuations are observed in many biological phenomena like gene expression, signaling, cell size regulation and growth. Notably, heterogeneity in cell size and growth rate often prevails and impacts tissue patterning and macroscopic growth robustness (1). Plant cell expansion is driven by turgor pressure and restrained by cell wall. Despite numerous studies (2,3), the spatial variation of turgor and its relation with cell-to-cell growth variability remain elusive. Here, using micro-indentation by atomic force microscope, we demonstrate that turgor is heterogeneous between adjacent cells in the epidermis of Arabidopsis shoot apical meristem. Combining experiments and physical modelling of cell wall mechanics and water movement, we show that cell size and tissue topology pattern heterogeneities in pressure and growth, reminiscent of a liquid foam. Pressure correlates either positively or negatively with cellular growth rate depending on conditions, suggesting that the meristem is at a tipping point between limitation of growth by cell wall extensibility and by water conductivity. Together, our results shed light on spatial variations of pressure and growth rate, with potential roles in tissue homeostasis.

Co-correspondence to Yuchen Long and Arezki Boudaoud

References
1. L. Hong et al., Annual Review of Plant Biology. 69, 469–495 (2018).
2. J. K. Ortega, Plant Physiol. 79, 318–320 (1985).
3. J. H. Kroeger, R. Zerzour, A. Geitmann, PLoS ONE. 6, e18549 (2011).