The advanced gene editing technique used by the researchers was nearly 100 percent efficient in knocking out the master gene behind flower formation, known as LEAFY.
“The flowers never developed to the point where ovules, pollen or fertile seeds were observed,” said Professor Steven Strauss. “And there was no detectable negative effect on tree growth or form.”
“A field study should be the next step to take a more careful look at stability of the vegetative and floral sterility traits, but with physical gene mutation we expect high reliability over the life of the trees.”
There are more than 700 species of eucalyptus, and most of them are native to Australia. The study was focused on a hybrid of two species, Eucalyptus grandis and E. urophylla, that is commonly found in the Southern Hemisphere.
“Roughly 7% of the world’s forests are plantations, and 25% of that plantation area contains non-native species and hybrids,” said study lead author Estefania Elorriaga.
“Eucalyptus is one of the most widely planted genera of forest trees, particularly the 5.7 million hectares of eucalyptus in Brazil, the 4.5 million hectares in China and 3.9 million hectares in India.”
According to the researchers, these plantings can lead to undesirable mingling with native ecosystems. Therefore, eliminating the ability of eucalyptus trees to sexually reproduce would be an effective way to reduce the potential for invasive spreading.
“This was the first successful application of CRISPR to solve a commercial problem in forest trees,” said Elorriaga. “Research with CRISPR in forest trees to modify different traits is ongoing in many laboratories around the world. Global warming is having large impacts on forests of all kinds, and gene editing may be an important new breeding tool to supplement conventional methods.”
Strauss said that despite the promising findings, trees genetically modified as they were in this research could not legally be planted in Brazil, where the cultivation of eucalyptus trees is highly profitable.
“The trait could not be used there due to laws against modifying plant reproduction with recombinant DNA methods,” explained Strauss.
“It would also be disallowed for field research or commercial use under sustainable forest management certification in many parts of the world – something scientists have come together to severely criticize in recent years.”
Strauss recently joined a coalition of forestry researchers to call for a review of what they see as overly restrictive policies regarding biotech research.
“Hopefully, studies like this one, that show how precise and safe the technology can be in modifying traits, and that help to promote ecological safety, will help to change regulations and certification rules. Happily, such discussions are well underway in many nations.”
The study is published in the journal Plant Biotechnology Journal.