3D deformation field in growing plant roots reveals both mechanical and biological responses to axial mechanical forces.
Strong regions and physical barriers in soils may slow root elongation, leading to reduced water and nutrient uptake and decreased yield. In this study, the biomechanical responses of roots to axial mechanical forces were assessed by combining 3D live imaging, kinematics and a novel mechanical sensor. This system quantified Young's elastic modulus of intact poplar roots (32MPa), a rapid <0.2 mN touch-elongation sensitivity, and the critical elongation force applied by growing roots that resulted in bending. Kinematic analysis revealed a multiphase bio-mechanical response of elongation rate and curvature in 3D. Measured critical elongation force was accurately predicted from an Euler buckling model, indicating that no biologically mediated accommodation to mechanical forces influenced bending during this short period of time. Force applied by growing roots increased more than 15-fold when buckling was prevented by lateral bracing of the root. The junction between the growing and the mature zones was identified as a zone of mechanical weakness that seemed critical to the bending process. This work identified key limiting factors for root growth and buckling under mechanical constraints. The findings are relevant to crop and soil sciences, and advance our understanding of root growth in heterogeneous structured soils.
UMR EEF, INRA, Université de Lorraine, 54280 Champenoux, France.
François
F
Bizet
James Hutton Institute, Ecological Sciences group, Dundee DD2 5DA, UK School of Science and Engineering, University of Dundee, Dundee DD1 4HN, UK glyn.bengough@hutton.ac.uk triboulo@nancy.inra.fr.
A Glyn
AG
Bengough
UMR EEF, INRA, Université de Lorraine, 54280 Champenoux, France.
Irène
I
Hummel
UMR EEF, INRA, Université de Lorraine, 54280 Champenoux, France glyn.bengough@hutton.ac.uk triboulo@nancy.inra.fr.
Marie-Béatrice
MB
Bogeat-Triboulot
James Hutton Institute, Ecological Sciences group, Dundee DD2 5DA, UK.
Lionel X
LX
Dupuy
D001696:Biomechanical Phenomena; D021621:Imaging, Three-Dimensional / Q000379:methods; D008954:Models, Biological; D018517:Plant Roots / Q000254:growth & development* / Q000502:physiology; D032107:Populus / Q000254:growth & development; D013314:Stress, Mechanical; D059008:Time-Lapse Imaging / Q000379:methods
3D imaging; Young’s elastic modulus.; biomechanics; buckling; kinematics; root growth
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