According to experts from The University of Western Australia (UWA) and Flinders University, an Australian seagrass clone has gained the title of “world’s biggest plant,” despite being 4,500 years old and spanning only 180 kilometers (112 miles). The finding happened by chance when researchers were looking at how many plants were in a seagrass meadow in Shark Bay and were surprised to find only one. The entire meadow was made up of a single large plant.
Poseidon’s ribbon weed, Posidonia australis, is the name of this award-winning seagrass. The clone stretches for at least 180 kilometers in the shallow seas of Shark Bay World Heritage Area in Western Australia, making it the world’s biggest known example of a clone in any habitat.
Poseidon’s meadow was discovered when researchers were requested to analyze the genetic diversity of seagrass meadows in the region. They collected seagrass shoots from Shark Bay, where marine plants can withstand temperature and salinity variations, and used 18,000 markers to create genetic fingerprints for the species they discovered.
How many plants did they discover?
“The answer blew us away – there was just one!” said Jane Egeloe of the University of Western Australia, who is the main author of a study on the plant published in Proceedings of the Royal Society B.
“That’s it; just one plant has spread over 180 kilometers in Shark Bay, making it the biggest known plant on the planet.” The current 200km2 of ribbon weed meadows appear to have grown from a single colonizing seedling.”
Aside from being a record-breaking seagrass clone, the gigantic plant is perplexing scientists since it lacks a sex life (sorry, P. australis) and hence has low genetic variety, making it sensitive to environmental change. However, the Poseidon Meadow appears to be adapting well to the recent alterations in Shark Bay.
“It experiences a tremendous variety of typical temperatures; from 17 to 30 °C,” said co-author and Flinders University ecologist Dr Martin Breed in a statement. “Salinities range from regular saltwater to double that.” And from complete darkness to extremely bright light. Plants would be extremely stressed in these settings. Nonetheless, it appears to be continuing.”
Its tolerance for extremes might be attributed to the fact that it contains twice as many chromosomes than its cousins, a condition known as polyploidy.
“When diploid ‘parent’ plants hybridize, whole genome duplication through polyploidy — doubling the number of chromosomes – happens,” explained UWA evolutionary scientist and lead author Dr Elizabeth Sinclair. “The new seedling possesses 100% of the genome from each parent, rather than the standard 50%.”
“Polyploid plants can live in harsh environmental circumstances, are often infertile, but may continue to grow if left alone, and this huge seagrass has done exactly that.”
The researchers intend to continue their research on Shark Bay’s Supersized Seagrass to learn more about how this mega-plant has grown so rapidly despite its ever-changing environment.