Lignin Discovery May Lead to Revision of Plant Evolution Timeline

What sets land plants apart from their aquatic counterparts is their ability to sprout upward through the air, unsupported except by their own woody tissues. Wood is composed of cellulose fibers impregnated with lignin molecules. Lignin-containing cell walls are considered to be key innovations in the evolution of terrestrial plants from aquatic ancestors some 475 million years ago. Lignin is of particular interest to biofuel researchers since it binds cell walls and prevents the extraction of cellulose, a key component in biofuel production.

Secondary growth and lignified cells are unique to vascular plants, or so scientists thought. A team of researchers from the University of Columbia and Stanford University has recently identified a marine alga with lignified cells. The scientists, in a paper published by Current Biology, noted that the finding “raises many questions about the convergent or deeply conserved evolutionary history of these traits, given that red algae and vascular plants probably diverged more than 1 billion years ago.”

Download the full paper at http://dx.doi.org/10.1016/j.cub.2008.12.031