Advance in understanding cellulose synthesis.

Cellulose is a fibrous molecule that makes up plant cell walls, gives plants shape and form and is a target of renewable, plant-based biofuels research. But how it forms, and thus how it can be modified to design energy-rich crops, is not well understood. Now a study led by researchers at the Carnegie Institution's Department of Plant Biology has discovered that the underlying protein network that provides the scaffolding for cell-wall structure is also the traffic cop for delivering the critical growth-promoting molecules where needed. The research, conducted in collaboration with colleagues at Wageningen University in the Netherlands and published in the advance online publication (AOP) of Nature Cell Biology on June 14th, is a significant step for understanding how the enzymes that make cellulose and determine plant cell shape arrive at the appropriate location in the cell to do their job (see also Carnegie Institution).

"Cellulose is the most abundant reservoir of renewable hydrocarbons in the world," remarked Carnegie's David Ehrhardt, a coauthor. "To understand how cellulose might be modified and how plant development might be manipulated to improve crop plants as efficient sources of energy, we need to first understand the cellular processes that create cellulose and build cell walls."

Plant cells have rigid walls that cannot easily change shape. There are many cell types, spiky trichomes to fend off bugs and sausage-shaped guard cells that regulate the plant's breathing pores, as examples. In a previous study using the model plant Arabidopsis, Ehrhardt and team used groundbreaking imaging techniques to watch the molecules that create this array of shapes. It provided the first direct evidence for a functional connection between synthesis of the cell wall and an array of protein fibers--called microtubules--that provide the scaffolding that allow diverse plant cell shapes to be created as the cell wall pushes outward.

In that study, the group engineered plants to produce a fluorescent version of cellulose synthase, the enzyme that creates cellulose fibers. They also included a fluorescent version of tubulin, the protein from ...