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Tree heat memory

By Country News

An Aussie eucalypt can remember past exposure to extreme heat, which makes the tree and its offspring better able to cope with future heatwaves, according to new research from Macquarie University.

The research team believes the finding could have important implications for restoring ecosystems and climate-proofing forestry, as the number of hot days and heatwaves increase due to climate change.

‘‘Unlike animals, which can bury deeper into the soil or flee to cooler locations, plants are stuck in one spot and so must be able to withstand extreme conditions (on site),’’ senior author Dr Rachael Gallagher said.

Dr Gallagher and her team looked at how different populations of Eucalyptus grandis seedlings, commonly known as flooded gum or rose gum, responded when they were exposed to a simulated four-day 42°C heatwave in the lab.

The researchers found that seedlings whose parents had experienced more days of extreme heat in the wild were better able to cope with the simulated heatwave conditions, because they made more protective proteins to protect their cells from heat stress.

These protective proteins act as molecular chaperones — meaning they transport other proteins to their correct locations within the cell, and help the cell to keep functioning normally despite the stress it is under.

‘‘This is a significant new finding,’’ Dr Gallagher said.

‘‘We have shown that trees have a molecular memory for extreme heat.’’

Compared to other plants like herbs and grasses, trees typically take a long time to mature and make new seeds. This may limit their ability to adapt to our rapidly changing climate.

‘‘By using this approach we can work out which populations might provide the best seed for restoring ecosystems and climate-proofing forestry as temperatures become more extreme,’’ Dr Gallagher said.

The study was conducted by Macquarie University’s Department of Biological Sciences, Department of Molecular Sciences and the Australian Proteome Analysis Facility.