First multicellularity: algae (Evolution)

by David Turell , Monday, May 09, 2016, 21:57 (3118 days ago) @ David Turell

Amoeba can come together and make stalk like structures and spores. Now an algae is found that is unicellular but the cells are held together in a gel and it has slightly differentiated parts:-http://www.scientificamerican.com/article/strange-seaweed-rewrites-the-history-of-green-plants/?WT.mc_id=SA_DD_20160509-"A mysterious deep-ocean seaweed diverged from the rest of the green-plant family around 540 million years ago, developing a large body with a complex structure independently from all other sea or land plants. All of the seaweed's close relatives are unicellular plankton.-"The finding, published today in Scientific Reports, upends conventional wisdom about the early evolution of the plant kingdom. “People have always assumed that within the green-plant lineage, all the early branches were unicellular,” says Frederik Leliaert.-***-"With more genes in hand, the scientists could better compare Palmophyllales to an ever-growing collection of green algae. It also allowed the researchers to use phylogenetic software to pinpoint when Palmophyllales branched off from related plant species.-"It turns out that the group diverged from the rest just after the green plants themselves split into their two main lineages, back when such plants were newfangled upstarts.-"Brent Mishler, a botanist at the University of California, Berkeley, finds the new work to be convincing. “It nails down the relationships,” he says. “The green plants are one of the most diverse branches on the tree of life, with a half million species that range in size from planktonic unicells to redwood trees. This paper makes a huge contribution to unravelling how this enormous and important lineage got started.”-"But although Palmophyllales split off early from other plants, its macroscopic size might not have developed until later in its evolution. And Leliaert says that he's wary of calling the seaweed “multicellular” because its cells are undifferentiated and suspended in a stiff gel. Still, he says, the whole plant has a distinct structure that includes a root-like holdfast, a stem, and blades. How the cells of the plant communicate with one another remains unknown.-"For Charles Delwiche, a molecular systematist at the University of Maryland in College Park, and one of the principal investigators of the Assembling the Green Algal Tree of Life project that supported the work, the result shows how little is known about green algae, despite the fact that they gave rise to all land plants."-Comment: We still don't know the full story but it looks lie a beginning for plant multicellularity.