Molecular Biology of Plant Pathways / Biochemistry and Molecular Biology of Cellulose Biosynthesis in Plants
Summary
Cellulose is a component of all plant cells, and modification of the cellulose
content or properties can have dramatic effects on the form and function(s) of
specific parts or the entire plant. Cellulose synthase is the enzyme required for
biosynthesis of cellulose, and a number of genes encoding this protein form part of a gene family in plants. Although plants are well endowed with genes for
cellulose synthases, and expression of most of the
CesA genes have been observed
in most tissues, mutations in some of them can have very different effects. At the
same time increased expression of some of the
CesA genes may result in increased
synthesis of cellulose in specific cells and tissues. More importantly, the direction
in which the cellulose microfibrils are assembled in the primary cell wall helps
determine the direction of cell elongation. In cells with a secondary cell wall, the
orientation of the cellulose microfibrils influences the properties of the cell.
Although the general view is that microtubules play a role in determining the
direction of cellulose synthesis, not much is known as to how this occurs. For
effective manipulation of cellulose synthesis in plant cells, it is necessary that we
not only understand the machinery responsible for cellulose biosynthesis, but also
as to how it is assembled, localized, and regulated.