06 January 2016
Plants crawled ashore earlier than thought
Researchers from the University of Copenhagen and Carlsberg laboratories were actually looking for a simpler model plant when they made a discovery that changes our current knowledge about the evolution of plants. They found evidence that today’s plants evolved from algae living on land – and not directly from algae living in water as previously assumed. The discovery is published in the scientific journal Trends in Plant Science.
Plant biologists generally agree that it all started with green algae. It is believed that this common ancestor of trees, ferns and flowers at a time in the history of life developed a new, alternative life cycle - probably with the result that their offspring were able to live on land.
But now science manager Jesper Harholt from Carlsberg Laboratories together with the University of Copenhagen professors Øjvind Moestrup from Department of Biology and Peter Ulvskov from the Department of Plant and Environmental Sciences, claim that some green algae have lived on land for hundreds of millions of years before this adjustment happened, and that land plants actually evolved directly from these land-based - and not aquatic - algae.
Botanists around the world have considered this possibility since 1980, but supporters of the theory have been lacking the evidence, that is now being presented by the Danish researchers in the form of decisive genetic and morphological discoveries. The strongest evidence is, that the features, which land plants use to survive on land today, is also found quite well-preserved in particular kinds of green algae.
The greatest challenge facing the researchers now to prove that an initial period of adjustment led to the complex cell walls of terrestrial plants today. The scientists believe that the land-based green algae were advanced enough to survive on a sandy surface with rainfall as the only source of water. The challenge is that only spores remain of plants from that period so the researchers a highly dependent on genetic studies to substantiate the theory.