Plant geneticists including Sam Hazen at the University of Massachusetts Amherst and Siobhan Brady at the University of California, Davis, now have a handle on the gene regulatory networks that control cell wall thickening by the synthesis of the three polymers, cellulose, hemicellulose and lignin. This breakthrough could have a positive impact on developing more efficient production technologies to convert cellulose to biofuels and biochemicals.
The authors say that the most rigid of the polymers, lignin, represents “a major impediment” to extracting sugars from plant biomass that can be used to make biofuels. Their genetic advance is expected to “serve as a foundation for understanding the regulation of a complex, integral plant component” and as a map for how future researchers might manipulate the polymer-forming processes to improve the efficiency of biofuel production.
According to the researchers, the three key components, found in plant tissues known as xylem, provide plants with mechanical strength and waterproof cells that transport water. Working in the model plant Arabidopsis thaliana, Hazen, Brady and colleagues explored how a large number of interconnected transcription factors regulate xylem and cell wall thickening. Results appeared in a recent issue of Nature.
The researchers write in the paper that “understanding how the relative proportions of these biopolymers are controlled in plant tissue would open up opportunities to redesign plants for biofuel use.” Hazen, Brady and colleagues’ study identified hundreds of new regulators and offers “considerable insight,” the authors say, “into the developmental regulation of xylem cell differentiation.”
Specifically, using a systems approach to identify protein-DNA interactions, they screened more than 460 transcription factors expressed in root xylem to explore their ability to bind the promoters of about 50 genes known to be involved in processes that produce cell-wall components. Hazen says, “This revealed a highly interconnected network of more than 240 genes and more than 600 protein-DNA interactions that we had not known about before.”