Scientists have found the largest plant on Earth – estimated to be at least 4,500 years old

Ribbon grass, Posidonia australis, grass in Shark Bay, Western Australia. Credit: Rachel Austin, University of Western Australia

Australian scientists believe they have discovered the largest plant in the world, and it is believed to be at least 4,500 years old.

Researchers at the University of Western Australia (UWA) and Flinders University found an old and extremely resistant seagrass that stretches for 112 miles (180 km).

Find a single seagrass plant or ‘clone’ Posidonia australis A new study published in the year shows water in shallow, sun-drenched waters of the Shark Bay World Heritage Area of ​​Western Australia. Proceedings of the Royal Society B.

The lead author, Dr. Elizabeth Sinclair, an evolutionary biologist at the UWA School of Biological Sciences and the UWA Oceans Institute, says the project began when scientists wanted to understand that Shark Bay meadows are genetically diverse and that marine plants should be harvested. restoration.

“We are often asked how many different plants grow in the seagrass and this time we have used genetic tools to address that,” says Dr. Sinclair.

UWA student researcher Jane Edgeloe, the lead author of the study, says the group sampled seagrass shoots in changing environments in Shark Bay and created a “fingerprint” using 18,000 genetic markers.

Shark Bay Western Australia

Shark Bay surface and salt water. Credit: Angela Rossen

“The answers surprised us: there was only one!” said Mrs. Edgeloe. “That is the only plant that has spread over 180 km in Shark Bay, and is the largest plant on Earth.

“It simply came to our notice then2 ribbon-grass meadows seem to have spread from a single colonizing plant. ‘

Co-author[{” attribute=””>Flinders University ecologist Dr. Martin Breed was part of the research group. He says the study presents a real ecological conundrum.

“This single plant may in fact be sterile; it doesn’t have sex. How it’s survived and thrived for so long is really puzzling. Plants that don’t have sex tend to also have reduced genetic diversity, which they normally need when dealing with environmental change,” says Dr. Breed, from the College of Science and Engineering at Flinders University.

“Our seagrass has seen its fair share of environmental change too. Even today, it experiences a huge range of average temperatures; from 17 to 30 °C. Salinities from normal seawater to double that. And from darkness to extreme high light conditions. These conditions would typically be highly stressful for plants. Yet, it appears to keep on going.

“How does it do it? Well, we reckon its genes are very well-suited to its local, but variable, environment and it also has subtle genetic differences across its range that help it deal with the local conditions,” Dr. Breed says.

Dr. Sinclair said what makes this seagrass plant unique from other large seagrass clones, other than its enormous size, is that it has twice as many chromosomes as its oceanic relatives, meaning it is a polyploid.

“Whole genome duplication through polyploidy – doubling the number of chromosomes – occurs when diploid ‘parent’ plants hybridize. The new seedling contains 100 percent of the genome from each parent, rather than sharing the usual 50 percent,” Dr. Sinclair says.

“Polyploid plants often reside in places with extreme environmental conditions, are often sterile, but can continue to grow if left undisturbed, and this giant seagrass has done just that.

“Even without successful flowering and seed production, it appears to be really resilient, experiencing a wide range of temperatures and salinities plus extreme high light conditions, which together would typically be highly stressful for most plants.”

The researchers have now set up a series of experiments in Shark Bay to understand how this plant survives and thrives under such variable conditions.

For more on this discovery, see World’s Largest Plant Stretches 112 Miles in Western Australia’s Shark Bay.

Reference: “Extensive polyploid clonality was a successful strategy for seagrass to expand into a newly submerged environment” by Jane M. Edgeloe, Anita A. Severn-Ellis, Philipp E. Bayer, Shaghayegh Mehravi, Martin F. Breed, Siegfried L. Krauss, Jacqueline Batley, Gary A. Kendrick and Elizabeth A. Sinclair, 1 June 2022, Proceedings of the Royal Society B.
DOI: 10.1098/rspb.2022.0538

The research was made possible through a collaboration between UWA, Flinders University and Kings Park Science (WA Department of Biodiversity Conservation and Attractions). It was funded by the Australian Government’s National Environmental Science Program Marine Biodiversity Hub and the Australian Research Council.

Leave a Comment