Lignin, according to Dr. Clint Chapple, Distinguished Professor of Biochemistry and the principal investigator (PI) in the new DOE-BER project, represents the single largest metabolic sink for phenylalanine in the biosphere—i.e., it is a huge metabolic commitment for plant metabolism. More than 108 gigatons of lignin are synthesized annually in the biosphere, Chapple notes.

Lignin is also a significant barrier to the use of crops for livestock feed, pulp and paper production, and to the generation of cellulosic biofuels.

The regulation of carbon allocation to the phenylpropanoid metabolism has been a focus of Dr. Chapple’s lab. Dr. Chapple is also the PI on a separate BER-funded award, “Regulation of Carbon Allocation to Phenylpropanoid Metabolism”, which was renewed in September 2011 for three years.

In 2010, members of the Purdue team reported finding the last undiscovered gene responsible for the production of phenylalanine, a discovery that could lead to processes to control the amino acid to boost plants’ nutritional values and produce better biofuel feedstocks. A paper on the work was published in the journal Nature Chemical Biology. (Earlier post.)

Scientists have been focused on getting the sugars out of cell walls and using microorganisms to ferment those sugars into fuel. We want to take advantage of a plant's metabolic pathways to make biofuel directly. We wouldn’t be able to literally squeeze fuel from the plants, but it would be close.

—Clint Chapple

Co-investigator Natalia Dudareva, a distinguished professor of horticulture, will focus on increasing phenylalanine production in plants. John Morgan, an associate professor of chemical engineering, will analyze the results of these efforts and develop mathematical models to determine the most efficient methods for rerouting phenylalanine and for making phenylethanol.

Chapple said the team would work with the common research plant Arabidopsis before applying any findings to a biofuel plant such as poplar trees or switchgrass.