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Poster De Conférence Année : 2015

Long distance signaling of mechanical stress in trees: evidence of hydraulic pulse

Résumé

Plants are constantly subjected to external mechanical loads such as wind, rain or even neighbours. These stimuli are known to affect the growth of the plants, a process called thigmomorphegenesis. Typically, the bending of a tree stem leads to a local increase of the radial growth while the primary growth is rapidly stopped, suggesting a transport of the information from the stimulated zone to the apical zone. Among the different hypothesis found in the literature to account for this long-distance transport (electrical signal, hormone transport), it has been proposed that local mechanical stimuli, like bending, could generate an hydraulic signal that could move through the xylem. Using stems segments, we displayed that bending strains generate a transient high pressure variation that is able to propagate rapidly along the hydraulic network. We quantified these pressure pulses and we observed i) that living cells were not involved in the phenomenon, ii) an inter-specific variability of its magnitude. Using a biomimetic approach and poroelastic artificial beams, we analyzed the physics of phenomena. We concluded that these hydraulic pulses are driven by the poroelastic properties of the saturated wood material and we proposed a physical modeling to explain the mechanism: the stem bending generates a variation of volume of the conduits, that expulses the incompressible water. This generates a local transient hydraulic overpressure. In planta experiments confirmed that hydraulic pulses propagate along the vascular system of the xylem symmetrically to the upper and lower regions of the stem. Finally, molecular analysis in the apical part of trees showed the evidence of a remote signalling induced by the bending of the basis of their stem. As a signaling process, this hydraulic behavior could be an efficient candidate for a fast long distance signal transporting mecanobiological information to the extreme organs as leaves, roots and apices
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Dates et versions

hal-01269106 , version 1 (05-02-2016)

Identifiants

  • HAL Id : hal-01269106 , version 1
  • PRODINRA : 310455

Citer

Eric Badel, G. Guena, Jean-François Louf, Aude Tixier, Nathalie Leblanc-Fournier, et al.. Long distance signaling of mechanical stress in trees: evidence of hydraulic pulse. 3. International Symposium on Plant, Signaling & Behavior, Jun 2015, Paris, France. Univ. Paris Diderot Publischers, 134 p., 2015, 3. International Symposium on Plant Signaling & Behavior. ⟨hal-01269106⟩
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