Why was the discovery of lignin in a red alga so surprising

Why was the discovery of lignin in a red alga so surprising?

What are the potential evolutionary implications of this discovery?

Be very specific and be sure that you carefully explain the classification of red algae as we knew it before this new discovery and the function of lignin in other plants groups.

THANK YOU!

Solution

Lignin is a chemical that gives wood its stiffness, was thought to be unique to land plants. But it has been found in red algae which emerged much earlier than land plants. As a result, it was much surprising to find lignin in a primitive life form. Scientists say that 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 existed long before algae moved to land. The discovery of polymerized hydroxycinnamyl alcohols (lignin) within the cell walls of a red alga has major evolutionary implications. Either the ability to synthesize lignin emerged in a single-celled ancestor or it emerged by convergent evolution in unrelated lineages. Since monolignol synthesis is quite complex, it seems unlikely that Calliarthron - the red alga and terrestrial plants evolved monolignol biosynthesis and polymerization totally independently. It seems more likely that relevant pathways like phenylpropanoid biosynthesis and polymerization by peroxidase-catalyzed oxidation are deeply conserved having evolved before the divergence of red and green algae more than 1 billion years ago. They also entertained the possibility that red algae and land plants converged on the highly-complex lignin pathways independently.