Researchers believe they have solved the mystery of how plants spread on land

Around 400 million years ago, plants managed to grow outside of swamps and riverbanks in much less watery habitats. To do this, they have developed complex systems to extract water from the soil more efficiently and to use photosynthesis. An evolution that has profoundly changed the atmosphere and terrestrial ecosystems. But how did it happen? It is this puzzle that a research team led by Yale University’s Department of Environmental Studies believes they have solved (Yale School of the EnvironmentYSE).

To achieve their results, published in the journal Science On November 10, 2022, researchers compared plant anatomy of extinct plants from the fossil record with material from the Yale-Myers Forest and greenhouses — among others — owned by the American University. A simple change in the structure of plants’ then simple and cylindrical vasculature would eventually have been enough to make them more drought-resistant and allow them to “explore” new horizons, they explain in a press release. Otherwise they would surely still look like mosses.

Combat the effects of drought with complex shapes

In fact, the first plants in their aquatic habitats had a vascular system that resembled a bundle of straws. But as they conquered the land, drought-induced air bubbles got stuck in their xylem, a specialized tissue that transports water and nutrients from their roots to stems and leaves. Consequence: the movement of water was blocked by bubbles that spread throughout the network, the plants died. They therefore had to develop more complex shapes to prevent these famous bubbles from circulating. So today plants present themselves “a variety of shapes of xylem strands in cross section, ranging from elliptical to linear to multilobed”write the authors in the study.

Every time a plant deviates from this cylindrical vasculature, every time it changes a little, the plant receives a reward in terms of its ability to survive drought. And if that reward is there all the time, it will force plants away from the old cylindrical vessels and into these more complex shapes – Craig Brodersen, team leader and professor of plant ecophysiology at the YSE.

⋙ Trunks, roots, dead leaves… The incredible mysteries of trees

An evolutionary reason in xylem modifications

Historically, observations of this increased vascular complexation in the fossil record have been considered fortuitous. “It’s not a coincidence. There’s actually a good reason scalable, refuted the first author of the study, Martin Bouda, in the press release. The scientists show here that it was these progressive changes in the organization of the xylem network that led to greater plant resistance to drier conditions and reduced the risk of hydraulic failure. Moreover, this diversification—which coincides with increases in plant size and branching—would have occurred fairly rapidly (for paleontological times) over about 20 to 40 million years.

This latest research should now inform research into selecting drought-resistant crops, particularly in the context of climate change, say the report’s authors.

Also read:

Watering plants with alcohol could help them survive drought

In the face of environmental stress, some plants produce their own aspirin

In the face of environmental stress, some plants produce their own aspirin

Exotic plants reflect colonization by European empires, study finds

Exotic plants reflect colonization by European empires, study finds

Leave a Reply

Your email address will not be published. Required fields are marked *