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Once upon a time, the eucalyptus tree was as exclusively Aussie as kangaroos or koalas. But when 19th century botanists discovered the many advantages of eucalyptus, they took varieties of this hardy genus and planted them all around the world.
They had reason to do so. The eucalyptus grows fast, spreads quickly, and produces high quality wood for ships, power poles, pulp, and railroad ties, not to mention a very useful oil. It also sucks up so much water via its roots that it can be used to dry out wetlands and swamps.
Today, vast forests of eucalyptus dominate landscapes around the world and provide valuable harvests of wood products in places as diverse as California, Kenya, Brazil, India, and China.
But there's a problem. The eucalyptus is an aggressive life-form, and wherever it gains a foothold, it charges into its new local ecosystem, wreaks havoc on indigenous flora and fauna, and drives out existing species. What's more, the oily, aromatic leaf canopies of the eucalyptus are highly flammable. Wherever there's eucalyptus, there's a risk of forest fire.
So, the eucalyptus issue is a "hot topic" among forest management scientists. They debate strategies to keep the many advantages of the eucalyptus while somehow limiting its environmental aggressiveness.
But solutions are at hand. And some of the most promising come from CRISPR—a technology used to precisely edit genes. A team of scientists led by Dr. Steve Strauss of Oregon State University is now experimenting with CRISPR to limit the ability of the eucalyptus to reproduce sexually. Their goal: to keep the benefits of existing trees but not allow them to run amok like weeds.
Using CRISPR, Professor Strauss is directing efforts to knock out the tree's LEAFY gene which controls flower formation and, ultimately, reproduction. "This could be a great means to prevent future spread from new plantings," Strauss said.
His team, including Estefania Elorriaga and Cathleen Ma, is working with gene-editing scientists from the University of Colorado, Beijing Forestry University, and the University of Pretoria. The greenhouse study involved a hybrid of two species, Eucalyptus grandis and E. urophylla, that are widely planted in the Southern Hemisphere.
The ultimate benefits of their hothouse program could be enormous. "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," said Elorriaga, a postdoctoral researcher at North Carolina State.
CRISPR Controlling Eucalyptus
Eucalyptus is a resourceful plant. However, it is an aggressive life-form that wreaks havoc on existing species. But solutions are at hand including CRISPR.
Their research will enable local economies to continue to harvest the tree—to provide transmission poles for massive rural electrification programs, for instance—while controlling the aggressive spread of the species. And the tree's contribution to increased forest cover and carbon sequestration would continue to work against climate change.
Strauss' eucalyptus program provides one more example of how precise, carefully monitored gene-editing can bring real world benefits to huge numbers of people.