To make biofuel, cut the lignin

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.