The findings, published in Nature Communications, could help to improve revegetation efforts in regions affected by bushfires.
During bushfires, organic compounds called karrikins, named after the Noongar word ‘karrik’, meaning smoke, are produced from burning plant material. Karrikins soak into the soil with the first rain after a fire and stimulate the germination of buried seeds.
The scientists from UWA’s School of Molecular Sciences and the ARC Centre of Excellence in Plant Energy Biology examined more than 400 species, and found that some appeared to have developed an enhanced sensitivity to karrikins.
Lead researcher Dr Mark Waters said it was known that plants use a special receptor called KARRIKIN INSENSITIVE 2 (KAI2) to detect karrikins. However, unlike most plants that carry only a single type of KAI2, some species had more receptors.
“We looked at plants we knew responded well to karrikins and found that one of these, an Australian weed commonly called wild turnip (Brassica tournefortii), had three KAI2 receptors,”
Dr Waters said.
“On closer examination we found that mutations in one of these three receptors were responsible for the improved karrikin sensing.”
Dr Waters said the scientists also found that by changing two amino acids in the KAI2 receptor of a plant they could turn it into a karrikin super-sensor.
“This is exciting because we have discovered a way in which KAI2 protein can evolve to change its sensitivity to karrikins,” he said. “It will be interesting to see if this discovery could be used in areas where revegetation efforts are needed.”
Of 400 plant species examined subsequently, the scientists found to their surprise that there were similar KAI2 mutations in nine species of flowering plants.
“One of these species is Hakea drupacea, an Australian native that has become an invasive weed in South Africa, and relies on fire to spread,” he said.
By understanding which native species are karrikin super-sensors the scientists hope their study can guide predictions of which plant species may germinate best when treated with karrikins and apply this knowledge to the revegetation of fire and mining-affected land.
Read the paper: Nature Communications
Article source: ARC Centre of Excellence in Plant Energy Biology
One of the world’s most widely used glyphosate-based herbicides, Roundup, can trigger loss of biodiversity, making ecosystems more vulnerable to pollution and climate change, say researchers from McGill University.
The widespread use of Roundup on farms has sparked concerns over potential health and environmental effects globally. Since the 1990s use of the herbicide boomed, as the farming industry adopted “Roundup Ready” genetically modified crop seeds that are resistant to the herbicide. “Farmers spray their corn and soy fields to eliminate weeds and boost production, but this has led to glyphosate leaching into the surrounding environment. In Quebec, for example, traces of glyphosate have been found in Montérégie rivers,” says Andrew Gonzalez, a McGill biology professor and Liber Ero Chair in Conservation Biology.
To test how freshwater ecosystems respond to environmental contamination by glyphosate, researchers used experimental ponds to expose phytoplankton communities (algae) to the herbicide. “These tiny species at the bottom of the food chain play an important role in the balance of a lake’s ecosystem and are a key source of food for microscopic animals. Our experiments allow us to observe, in real time, how algae can acquire resistance to glyphosate in freshwater ecosystems,” says post-doctoral researcher Vincent Fugère.
The researchers found that freshwater ecosystems that experience moderate contamination from the herbicide became more resistant when later exposed to a very high level of it – working as a form of “evolutionary vaccination.” According to the researchers, the results are consistent with what scientists call “evolutionary rescue,” which until recently had only been tested in the laboratory. Previous experiments by the Gonzalez group had shown that evolutionary rescue can prevent the extinction of an entire population when exposed to severe environmental contamination by a pesticide thanks to the rapid evolution.
However, the researchers note that the resistance to the herbicide came at a cost of plankton diversity. “We observed significant loss of biodiversity in communities contaminated with glyphosate. This could have a profound impact on the proper functioning of ecosystems and lower the chance that they can adapt to new pollutants or stressors. This is particularly concerning as many ecosystems are grappling with the increasing threat of pollution and climate change,” says Gonzalez.
The researchers point out that it is still unclear how rapid evolution contributes to herbicide resistance in these aquatic ecosystems. Scientist already know that some plants have acquired genetic resistance to glyphosate in crop fields that are sprayed heavily with the herbicide. Finding out more will require genetic analyses that are currently under way by the team.
Read the paper: Nature Ecology & Evolution
Article source: McGill University
Image credit: Vincent Fugère
