Fita daninha, Posidonia australis, prado em Shark Bay, Austrália Ocidental. Crédito: Rachel Austin, Universidade da Austrália Ocidental
Cientistas australianos acreditam ter descoberto a maior planta do mundo – e estimam que ela tenha pelo menos 4.500 anos.
A antiga e incrivelmente resiliente erva marinha que se estende por 180 km foi localizada por pesquisadores da Universidade da Austrália Ocidental (UWA) e da Universidade Flinders.
A descoberta da única planta ou ‘clone’ das ervas marinhas Posidonia australis nas águas rasas e ensolaradas da Área de Patrimônio Mundial de Shark Bay, na Austrália Ocidental, é detalhada em um novo estudo publicado em Anais da Royal Society B.
A autora sênior, bióloga evolucionária Dra. Elizabeth Sinclair, da Escola de Ciências Biológicas da UWA e do Instituto UWA Oceans, diz que o projeto começou quando os cientistas queriam entender quão geneticamente diversificados eram os prados de ervas marinhas em Shark Bay e quais plantas deveriam ser coletadas para ervas marinhas. restauração.
“Muitas vezes nos perguntam quantas plantas diferentes estão crescendo em prados de ervas marinhas e desta vez usamos ferramentas genéticas para responder”, diz o Dr. Sinclair.
A pesquisadora da UWA Jane Edgeloe, principal autora do estudo, diz que a equipe coletou amostras de brotos de ervas marinhas de ambientes variáveis de Shark Bay e gerou uma ‘impressão digital’ usando 18.000 marcadores genéticos.
As águas rasas e salgadas de Shark Bay. Crédito: Ângela Rossen
“A resposta nos surpreendeu – havia apenas uma!” disse a Sra. Edgeloe. “É isso, apenas uma planta expandiu mais de 180 km em Shark Bay, tornando-se a maior planta conhecida na Terra.
“Os 200 km existentes2 de prados de ervas daninhas parecem ter se expandido a partir de uma única muda colonizadora.”
Coautor[{” 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.
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