Green Plants’ History Could Be Rewritten By Mysterious Seaweed

Around 540 million years ago, a strange deep ocean seaweed separated from the rest of the green plant kingdom. The species independently evolved into a large body with an intricate structure that was different from all other plants found in water or on land. According to a new study, the present day relatives of the seaweed are unicellular plankton.

As per a study published in Scientific Reports, the discovery changes everything that is currently known about the early evolution of plants. "People have always assumed that within the green-plant lineage, all the early branches were unicellular," says Frederik Leliaert, evolutionary biologist from Belgium's Ghent University. "It is quite surprising that among those, a macroscopic seaweed pops up."

Today, there are only a few known species of the strange seaweed known as Palmophyllales, and all its types live deep below the ocean's surface, at depths more than 80 meters.  Leliaert was one of the first researchers who investigated the genetics of the species five years ago. At first, the Palmophyllales seaweed looked similar to the common types of green algae, however on careful analysis it was found to be only very remotely related to any other macroscopic green algae, or for that matter any plant found on land. The scientists understood that it was a different species at that time.

It is only now that researchers have traced the evolution map of the mysterious seaweed, and it position in the plant kingdom. A specimen was taken from the Gulf of Mexico, and with next generation sequencing technologies, it become more reasonable to study the genome of Palmophyllales' chloroplast, which is the structure that produces energy in a plant cell. The researchers could conduct a better comparison of Palmophyllales with green algae.

On the basis of the analysis, it was found out that the strange seaweed had separated from the rest just after green plants bifurcated into two main types during the very start of their evolution. The macroscopic size of the Palmophyllales developed much later, and scientists are wary of calling it multicellular. According to a report in Nature journal, researchers are saying "the tree of life will become a lot shrubbier ". The study show how little is actually known about green algae though they led to the evolution of plants on land.