Billion-yr revision of plant evolution timeline may stem from discovery of lignin in marine algae

Washington, Jan 28 (ANI): A team of scientists has found lignin in marine algae, which may lead to a billion-year revision of the plant evolution timeline.

Lignin, a principal component of wood, is a glue-like substance that helps fortify cell walls and is instrumental in the transport of water in many plants.

Now, the chemical, which is vital to the self-supporting nature of land plants, and thought unique to them, has been found in marine algae by a team of researchers including scientists at UBC and Stanford University.

Study lead author Patrick Martone and colleagues used powerful chemical and microscopic anatomy techniques to identify and localize lignin within cell walls of a red alga that thrives along the wave-swept California coast.

Martone conducted the work in the laboratory of co-author Mark Denny, Professor of Biology at Stanford's Hopkins Marine Station.

"All land plants evolved from aquatic green algae and scientists have long believed that lignin evolved after plants took to land as a mechanical adaptation for stabilizing upright growth and transporting water from the root," said Martone, an assistant professor in the UBC Dept. of Botany, where he is continuing his work on lignin.

"Because red and green algae likely diverged more than a billion years ago, the discovery of lignin in red algae suggests that the basic machinery for producing lignin may have existed long before algae moved to land," he added.

Alternatively, algae and land plants may have evolved the identical compound independently, after they diverged.

"The pathways, enzymes and genes that go into making this stuff are pretty complicated, so to come up with all those separately would be really, really amazing," said Denny. "Anything is possible, but that would be one hell of a coincidence,"

The team's finding provides a new perspective on the early evolution of lignified support tissues - such as wood - on land, since the seaweed tissues that are most stressed by waves crashing on shore appear to contain the most lignin, possibly contributing to mechanical support, according to Martone.

The new discovery may affect one of the ways land plants are distinguished from aquatic algae in textbooks - by the presence of lignin.

It is also of interest to biofuel researchers since lignin binds cell walls and prevents the extraction of cellulose, a key component in biofuel production. (ANI)