To make biofuel, cut the lignin

Researchers disable key protein, make plant sugars easier to access

PLANT SUPPORT  Lignin (stained red) keeps plant cell walls sturdy  and strong but is hard to break down during biofuel production. By maiming a protein that helps  make the woody molecule, researchers can cut lignin levels and gather more  biofuel-usable sugars from plants.

Courtesy of Lisa Sundin

Plant stems and leaves are tough, but breaking them down doesn’t have to be. By crippling a single protein, researchers can grow plants that have 36 percent less lignin, the sturdy plant-wall molecule that makes chewing up plants for biofuel production so difficult.

Lignin (the name comes from the Latin word for wood) forms the support beams of plant cell walls. The molecular beams stiffen stems, letting plants stand straight and tall. But for scientists trying to capture sugars studded throughout plants’ walls, stiff bits of lignin are a problem.

To pull out the sugars to make biofuels, scientists usually chop up lignin-reinforced plant pieces with chemicals and enzymes — a laborious and expensive process. So plant biologist Ruben Vanholme of Ghent University in Belgium and colleagues searched for a way to prevent plants from making the hardy molecule in the first place.

The researchers knocked out the enzyme caffeoyl shikimate esterase, a worker in lignin’s assembly line in a small flowering plant. Lignin production dropped and the plant’s sugars became easier to access, the researchers report August 15 in Science.

Because biofuel feedstock plants such as switchgrass, poplar and eucalyptus may also house the enzyme, disabling it may help scientists jack up biofuel production.

Meghan Rosen is a staff writer who reports on the life sciences for Science News. She earned a Ph.D. in biochemistry and molecular biology with an emphasis in biotechnology from the University of California, Davis, and later graduated from the science communication program at UC Santa Cruz.

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