第1213回生物科学セミナー

Toward the identification of molecular players involved in the building of tension wood mechanical properties

Dr. Gilles Pilate(BioForA, INRA)

2018年06月11日(Mon)    15:00-16:00  理学部2号館 講堂   

In response to environmental cues, hardwood trees produce tension wood, a peculiar wood with remarkable mechanical properties. Indeed, tension wood generates strong tensile maturation stresses, much greater than those observed in normal wood. Thanks to the production of tension wood, the tree is able to withstand its own weight, to orientate its axes in response to gravity and light signals, and to provide the stem with greater resistance against the prevailing winds. In poplar, as in most temperate tree species, the cell wall of tension wood fibers possesses an additional layer, the G-layer, rich in crystalline cellulose with microfibrils oriented parallel to the fiber axis. The mechanism responsible for generating high tensile maturation stress in tension wood fibers remains unclear. It has been shown that the cellulose microfibrils of the G-layer are under high tensile stress. It remains unclear how cellulose microfibrils are placed under tension, and how this tension is transmitted to the other cell wall layers. Several models for the generation of TW maturation stress have been proposed, but none has been definitively validated. Some recent studies have shown that the G-layer has a gel-like structure leading to hypothesize that the swelling of this gel in response to changes in water content or ion concentrations underlies the generation of growth stress in the cellulose microfibrils of the G-layer. This implies that the formation of this gel results from changes in the composition of the G-layer matrix. In this talk, I will present the last results obtained toward identifying matrix components responsible for the strong tensile stress present in tension wood.