Growing Straight : Evidences of active proprioceptive control in plants

International audience

Inglés. Straight growth of slender organs under gravity is unstable. This has been known for long for vertical straight growth, due to Euler self-buckling. However, both primary and secondary growth lock-in and amplify any curvature, leading to a slow instability of the straight configuration [1, 2]. Moreover, mechanisms that were thought to control growth orientation and organ shape, such as gravitropism and phototropism were shown not to solve the problem and even to generate more dynamical instabilities in growth control [2,3,4]. Ten years ago, we proposed and demonstrated that proprioception -the sensing by the plant of its local curvatures -, and proprioception-driven autotropism could solved this problem [3]. This was achieved by combining spatiotemporal modelling, mathematical analysis, and model assessment in 13 species sampling the phylogeny on land plants. Later on, further evidences converged toward the genericity of proprioception in plants [5]. However direct experimental demonstration of proprioception and the active drive of autotropic straightening was missing. Here we show, using novel set-ups allowing to deconvolution of proprioceptive drive, that proprioception is occurring in the primary growth of the herbaceous model plant Arabidopsis thaliana and in the secondary growth of the tree model species Populus temula x alba. Finally we also illustrate an At myosin mutant with modified proprioceptive sensitivity. All this opens a straight…forward avenue toward a more complete understanding of the mechanosensitive shape control in plants [5,6,7]. [1]MOULIA B , BASTIEN, R., CHAUVET H, LEBLANC-FOURNIER N., 2019 Posture control in land plants: growth, position sensing, proprioception, balance, and elasticity. Journal of Experimental Botany, Vol. 70 (14) :. 1 3467-3494,[2]R.BASTIEN, S.DOUADY†, B. MOULIA.†* , 2014, A Unifying Modeling of Plant Shoot Gravitropism With an Explicit Account of the Effects of Growth . Frontiers in Plant Sciences (Plant Biophysics) 5:136. doi: 10.3389/fpls.2014.00136. ( † co-PI last authors, * corresponding author )[3]R.BASTIEN, T. BOHR, B. MOULIA.† * , S.DOUADY.† , 2013 . A unifying model of shoot gravitropism reveals proprioception as a central feature of posture control in plant. PNAS 110 (2 ): 755–760 († co-PI last authors, * corresponding author )[4]BASTIEN, R., DOUADY, S†., MOULIA, B †*. 2015. A Unified Model of Shoot Tropism in plants: Photo-, Gravi- and Propio-Ception. PLOS Computational Biology, DOI:10.1371/journal.pcbi.1004037 Feb (co PI authors, * corresponding author)[5]MOULIA B., DOUADY S. AND HAMANT O., 2021 Fluctuations shape plants through proprioception. Science 372, eabc6868 doi: 10.1126/science.abc686[6]BASTIEN, R., GUYASAMIN, O, DOUADY, S., MOULIA, B . 2018 Coupled ultradian growth and curvature oscillations during gravitropic movement in disturbed wheat coleoptiles. PLoS One, 13(3): e0194893.[7]MEROZ Y (2021) Plant tropisms as a window on plant computational processes. Tansley Insight, New Phytologist, 229(4),1911–1916