Wine and frost don’t mix: University of Melbourne researchers tackle ice-triggering bacteria on grapevines.
Media Release, Thursday 6 March 2008
University of Melbourne researchers have identified bacteria in grapes which trigger frost damage - a problem that causes average crop losses of more than $33 million a year in Victoria and South Australia.
According to a recent study at the University of Melbourne's Dookie Campus, the ice nucleating strain of the bacterium Pseudomonas syringae - known to be present on vines in the US and Europe - has been identified for the first time in Australia.
Dr Tom Hill and Sonja Needs, researchers at VitUM, the University’s Viticultural Research Group, have found the bacteria trigger the freezing of dew on leaves at much higher temperatures than occurs on bacteria-free leaves, rapidly killing the entire plant shoot.
The study adds to recent findings that the same bacteria are found in snowfall and hail around the world, where they may initiate ice crystals- essential for both snow and rain in temperate climates (Science, 29th Feb 2008, p1214).
Climate change will, paradoxically, only increase their frequency. Existing counter-measures raise the temperature around the plants; an expensive, inefficient approach afforded by few. A novel strategy may be possible, to lower the temperature at which the plants freeze, by inactivating the ice bacteria that trigger freezing (without them the leaves to do not freeze until below -50C).
This could be achieved by killing the bacteria, displacing them with ‘friendly’ naturally-occurring strains of the same species that do not carry the ice genes, or by inhibiting their production of the ice protein.
Researchers are currently developing a method, using DNA-based tools, designed to count them, and develop novel, sophisticated and elegant anti-frost treatments that work in the vineyard.
“These microscopic predators live on the leaf and generate ice crystals which spread, penetrating like spears. This destroys the cell structure enabling the bacteria to engulf the leaf. Next morning, when it thaws, they feast, killing the entire shoot.” says Dr Hill.
“They are true Jekyll and Hyde bacteria”, added Tom Hill. “Their good side may be making rain, acting as organic cloud seeding particles. But their bad side is brutal: they may be responsible for causing the millions of dollars of frost damage to not only vines but other horticultural crops as well.”
For more information: www.landfood.unimelb.edu.au/vitum/
For more information:
Dr Tom Hill
VitUM (Viticultural Research at the University of Melbourne)
Faculty of Land and Food Resources
Office: 03 5833 9200
Mob: 0416 041 729
Email: tchill@unimelb.edu.au
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