2022 – Australian scientists discover “the largest plant on Earth” off the coast of Washington | Ocean

About 4,500 years ago, a single seed — grown from two different types of seaweed — was found in a niche somewhere in what is now Shark Bay off the west coast of Australia.

Left to its own devices and relatively undisturbed by human hands, the seed has grown into what is believed to be the largest plant on Earth, and covers about 200 square kilometers (77 square miles, or about 20,000 rugby fields, a little) more than three times the size of an island Manhattan).

Genre – A Posidonia australisAlso known as complex weeds or tape weeds – they are most commonly found on the southern coasts of Australia.

But when scientists began looking for genetic differences in the tape plant across the bay, they faced a mystery. The samples taken from the sites that are separated by a distance of 180 km indicated the absence of several samples from posidonia australia, But one plant.

Dr. said. Martin Breed, an ecologist at Flinders University. “We were confused.”

About 18,000 genetic markers were examined as they searched for differences in species that could help them select specimens for use in restoration projects, University of Western Australia (UWA) researcher Jane Idjello said.

Instead, they found that the plant itself propagated using roots in the same way that grass can spread from its edges by sending stolons.

“It appears that the existing meadows of 200 square kilometers have expanded from a single plant colony,” she said.

The lone plant now spreads out like meadows, providing a home to a variety of marine species including turtles, dolphins, dugongs, crabs, and fish.

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Tapegrass roots can grow up to 35 centimeters per year, and at this rate the authors of the paper — published in Proceedings of the Royal Society B — estimated that the plant would have taken at least 4,500 years to spread that far so far.

They did not give the plant a nickname, said Dr Elizabeth Sinclair, a co-author on the research at the University of Western Australia, and that the original samples – taken from a seagrass meadow – originally had 116 different labels with GPS coordinates when stored at freezing depth ready for sampling. genetic.

The plant forms huge, dense lawns, some of which extend as far as the eye can see in all directions. The strips of the plant are up to 10 cm long in some places and up to a meter in others.

The spread of the plant can be seen in this aerial view of Shark Bay. Photo: Angela Rosin

Conditions at Shark Bay itself are tough. The plant has found a way to survive in areas where the salinity is twice that of elsewhere in the bay and can thrive in temperatures as low as 15°C and as low as 30°C.

Sinclair said the survival of the seaweed plant appears to be linked to how it retains all of its parents’ chromosomes, giving it endogenous genetic diversity.

“Instead of getting half [of] Her genes are from my mom and half from my dad, she kept them all.”

Sinclair and her colleagues are still working on the mysteries of the giant specimen, but she said it appears “largely sterile” and therefore should rely on its ability to grow rather than disperse seeds.

The fact that the plant “didn’t have sex” but survived all this time is a mystery, Breid said.

“Asexual plants also tend to have lower genetic diversity, which is what they usually need when dealing with environmental changes,” he said.

Breed said they discovered some very subtle mutations in the plant’s genes in the places where it grew that could also explain its extreme longevity.

The Shark Bay Ribbon Weed has a size of about 20,000 hectares (49,000 acres)—much larger than the area of ​​Aspens in Utah. Often referred to as the largest plant in the world, it covers an area of ​​43 hectares.

Associate Professor Catherine McMahon of Edith Cowan University was not involved in Shark Bay research but is an expert in seaweed. She said the method the researchers used gave her confidence that they had identified one specimen, which she described as “amazing.”

Genetic studies of other seaweed species have estimated that plants can live anywhere from 2,000 to 100,000 years, so McMahon said the estimate that the Shark Bay sample was 4,500 years old fits that range.

“They have a versatile growth pattern that contributes to this long life,” she said. “They can grow toward nutrient-rich patches to get to the nutrients they need, toward gaps in a lawn where they have room to grow, or away from stressed places.

“All of these qualities mean that if it’s in the right place, it can last a long time.”