Freezing Avocado Shoots: the ‘Han Solo Treatment’ Security Blanket

Brian German Fruits & Vegetables, Industry

Researchers have recently developed a protocol for preserving avocado shoots that will help ensure the integrity of the avocado germplasm. Successful cryopreservation of avocado plant material has taken more than 40 years of effort. In partnership with The Huntington Library, Art Museum and Botanical Gardens in California, University of Queensland Ph.D. student Chris O’Brien has finally developed a method for effectively cryopreserving avocado shoots.

Avocado Germplasm
Courtesy: University of Queensland

“It’s the first time that this work has been done with avocado shoot tips, so it’s quite exciting,” said O’Brien. “We basically just want to back up the germplasm because in America you guys have got a fungus called laurel wilt which the industry is quite worried about. The people in Florida are worried about losing their germplasm to this fungus. So, it’s just a way of backing up those trees.”

After encountering some issues with browning, O’Brien worked out a process to effectively freeze the plant material. The shoot tips are treated with cryoprotectants to protect the shoot tips from getting damaged by the liquid nitrogen. The material can then be stored indefinitely in liquid nitrogen. O’Brien noted that they have optimized the protocol for two cultivars. The Reed cultivar will be used for field testing the successful rewarming of the frozen shoot tip. “It’s a fully rooted plant and there’s 80 of those. We’re planning on planting those out to use in a field trial this year,” O’Brien explained

The U.S. Department of Agriculture’s Agricultural Research Service has germplasm repositories in Miami, Florida, and Mayaguez, Puerto Rico. The potential issue with field repositories is that the trees are still vulnerable to pests, disease, and weather. The cryopreservation protocol provides another method for safeguarding the avocado germplasm while offering added benefits compared to field repositories.

“It’s quite costly to maintain these field germplasms. You always need money to buy fertilizers and someone needs to prune the trees and you need to look after them…and it takes up quite a lot of room. Another advantage of cryopreservation is you can store thousands of trees within a small area,” said O’Brien. “Cryopreservation is not going to take over field repositories, it’s just going to be used as a complementary method.”

Listen to the interview below.

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Brian German

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Multimedia Journalist for AgNet West