Master 2

Tension wood results from the differential maturation of wood cells derived from the cambium between opposite sides of the trunk of the tree to achieve its adaptive reorientation after tilting. Aquaporins PIP, channel proteins which facilitate the passage of water across the plasma membrane seem to be involved in the formation of normal wood. This study is based on the hypothesis that PIP aquaporins are involved in the formation of tension wood by differentially regulating the water flow between the two sides of the stem after gravistimulation.

Using an ecophysiological approach, changes in local water flow from the upper to the lower side of the 35° inclined stem were highlighted. Using qRT-PCR, modulations of expression of PIP were observed. Cytological techniques allowed to detect the change of PIP distribution in the stem after gravistimulation. These results suggest that the water movements caused by the inclination may be due to changes in radial transport of water in the stem and this, via the cellular regulation of PIP aquaporins.