Scientists have figured out the evolution of the first roots in terrestrial plants thanks to a fossil found in Scotland. Researchers in the UK and Austria have created a 3D reconstruction of a Devonian plant based solely on its fossilized footprint.
The data they obtained indicate that the evolutionary processes that led to the emergence of the root as a separate organ began shortly after the appearance of the terrestrial plants themselves, that is, just over 400 million years ago.
Let us explain that the first plants to emerge on land had no roots, were small and grew in close proximity to water, which guaranteed their survival. The emergence of the root was a watershed event in the evolution of plants and life on Earth as we know it.
After all, the roots allowed the plants to receive more nutrients from the soil, gave them support so that the stems could come off the surface and receive more sunlight. Plants gradually began to increase in size and create a new ecosystem, more and more suitable for other life forms.
"Their evolution, change and distribution around the world has had a significant impact on the Earth system. Plant roots have reduced atmospheric CO2 levels, stabilized the soil and dramatically altered the water cycle on the continental surface," says lead author Alexander J. Hetherington from the University of Edinburgh.
The plant, whose 3D model was recreated by scientists, belongs to the extinct species Asteroxylon mackiei from the also extinct genus Asteroxylon. It is a representative of the ancient division of lycopods. Today, such representatives of this department grow on the planet as the lamb, selaginella and polushnik.
The 3D reconstruction shows a branchy shoot (shown in green) and a root system (blue and purple).
Illustration by Sandy Hetherington.
3D reconstruction allowed scientists to recreate information not only about the structure, but also about the development of the organs of an ancient plant. The fact is that early interpretations of the structure of this fossil lymphoid were based only on a comparison of fragmentary prints with existing plants.
It turned out that the roots of this plant developed in a special way, which is no longer observed in modern plants. This suggests that such a root formation mechanism is a past stage of evolution.
"These are the oldest known structures, reminiscent of modern roots. We now know how they were formed. They emerged when the shoots formed a fork, in which one prong retained the properties of the shoot, and the other received the properties of the root," explains co-author Liam Dolan (Liam Dolan) of the Gregor Mendel Institute for Plant Molecular Biology.
The studied fossil has been waiting for its hour on the museum shelf for hundreds of years. The authors of the work note that this work is not the last of its kind: thousands of other exhibits are stored in museum storerooms. Studying them with the help of new technologies will provide exciting answers to key questions of science.
The results of the current study were published in eLife.