A researcher at the University of Queensland in Australia has become the first person ever to freeze the tips of avocado shoots in liquid nitrogen and successfully revive them to create healthy plants in a bid to protect the world’s avocado supplies.
PhD student Chris O’Brien has developed the first critical steps to create a cryopreservation protocol for avocado which had never been achieved until now, despite more than 40 years of research.
The future of the fruit has been under threat in recent years due to bushfires, pests and diseases such as laurel wilt – a fungus which has the capacity to wipe out all the avocado germplasm in Florida, O’Brian said.
But thanks to O’Brian’s world-first research, important avocado cultivars and key genetic traits have been preserved and saved from possible destruction.
“Liquid nitrogen does not require any electricity to maintain its temperature, so by successfully freezing avocado germplasm, it’s an effective way of preserving clonal plant material for an indefinite period,” O’Brian said.
Cryopreservation is the technology used to freeze human biological material such as sperm and eggs at minus 196 degrees Celsius and has been used to freeze other plants such as bananas, grape vines and apple.
The avocado shoot tips are placed on an aluminium foil strip, which allows for ultra-fast cooling and rewarming, then placed into a ‘cryotube’ before being stored in liquid nitrogen.
The frozen shoot tips can be revived in a petri dish containing a sucrose mixture to rehydrate.
“It takes about 20 minutes to recover them. In about two months they have new leaves and are ready for rooting before beginning a life in the orchard,” O’Brian said.