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Eucalypt genome shows jet fuel potential

Iconic blueprint The genetic blueprint of an iconic Australian tree opens the way for better production of wood, medicines and possibly even eucalypt-based jet fuels.

The genome of Eucalyptus grandis (flooded gum) is published today in the journal Nature.

Native to the coastal regions of New South Wales and Queensland, flooded gum has become the species of choice for timber plantations across the world due to its hardy nature, fast growth rate and excellent quality of wood.

And now, armed with its genetic sequence, Professor Alexander Myburg from the University of Pretoria in South Africa, says there is tremendous potential to further improve the commercial value of this important species.

"Eucalypts are by far the most widely-grown fibre crop in the world and so there is big interest in understanding why they grow so fast and why they produce such large amounts of wood," says Myburg, who led the study.

"In one sweep we now have access to the full genetic blueprint of the tree, so we can see under what circumstances which particular genes are turned on or off."

By knowing which genes are important for determining key characteristics, Myburg says there is potential for breeding trees that grow faster, use water more efficiently and which will be better able to cope with climate change.

The process of selectively breeding the eucalypts will also be accelerated as there is no longer the need to wait decades for them to mature to see what traits they possess.

"If you can already predict a tree's qualities with good reliability at the seedling stage, then you can grow only the ones that are predicted to have very good properties," Myburg says.

The new study, which also provided insight into the evolutionary history of eucalypts, took five years of research involving 80 scientists from 18 countries.

Terpenes and jet fuel

Dr Carston Küllheim from the Australian National University, who was also involved in the study, says the research provides insight into eucalypt production of useful chemicals known as terpenes.

The eucalypt genome had the largest number of genes for producing terpenes of any plant species that has been genetically sequenced so far.

Terpenes are hydrocarbons that act as chemical defences against pests, and that provide aromatic oils used in medicinal and pharmaceutical applications.

They also increase the flammability of eucalyptus leaves, adding to their susceptibility to fire.

Some derivatives of terpenes may be converted into advanced biofuels, which Küllheim says could provide an alternative to petroleum-based fuels in the future.

The terpene derivatives have the same number of carbon in the backbone like diesel fuel, adds Myburg.

"This means that in future we could use specially selected eucalyptus genes in bacteria and yeasts, turning them into bio-factories to manufacture advanced biofuels on a large scale," he says.

"In future, jumbo jets may take off powered by renewable, eucalyptus-based fuel."