Baskin, Tobias .
Form follows Structure: Anisotropic Expansion of Higher Plants.
Who has not marveled at plant forms? The shapes of plant organs arise by expansion. Cell walls deform under turgor pressure and the shape of the organ represents the integral of all of this deformation over all of the cell walls. Turgor is hydrostatic pressure and is isotropic; plant cell walls almost always deform anisotropically. The origin of the anisotropy can derive from the distribution of stresses within the wall as well as from the anisotropic material properties of the cell wall. Pioneering work of Paul B. Green showed that expansion anisotropy in green algal cells tends to be constant. I will present data for the roots of vascular plants indicating that expansion anisotropy varies greatly as a function of tissue and treatment. Therefore, we need to explain how expansion anisotropy is controlled. My colleagues and I tested a hypothesis that posits the control is exerted by the degree of alignment among cellulose microfibrils. I will present evidence from polarized light microscopy and high resolution scanning electron microscopy to support that hypothesis, provided it be understood to mean that it is the variation of cellulose alignment globally over the whole organ and not the alignments of individual microfibrils.
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1 - University of Massachusetts, Biology Department
Presentation Type: Special Presentation
Location: Stevens 5/Hilton
Date: Wednesday, July 11th, 2007
Time: 10:00 AM