Tobias Baskin, biology, recently received a $238,000 grant from the Department of Energy to study cellulose and plant control of anisotropic growth, that is, growth rates that are not equal in all directions.
As he explains, “Anisotropy is a hallmark of plant growth. Almost without exception, cells grow faster in one direction than in another.” He will study such questions as how a plant makes organs with specific and heritable shapes, for example, how it builds flat leaves appropriate for catching the sun’s rays and cylindrical roots for foraging soil nutrients.
“In plants, the shapes of organs are controlled by growth. When growth is the same in all directions, it is isotropic, and this kind of growth gives rise to spherical structures, such as a blueberry,” he points out. However, “most plant organs are far from spherical and require growth to differ in different directions, that is to be anisotropic. Growth in plant cells is powered by hydrostatic pressure, which in typical plant cells exceeds that of the typical automobile tire, and is controlled by the mechanical anisotropy of the cell wall.”
Further, “the latter is in turn controlled by cellulose, a polymer with a tensile strength rivaling that of steel. Plant cells control growth anisotropy by controlling the direction in which cellulose is deposited in the cell wall.”
His renewed grant aims to understand this process, taking advantage of a single cell system. He will quantify the rate and direction of cellulose synthesis in living cells, perturbed experimentally, and related to the expansion patterns of the same cells.