A researcher at the University of Pretoria (UP), Prof. Zander Myburg, was the lead investigator in a global project to unravel the genetic blueprint of Eucalyptus grandis, a species from a genus of fast-growing trees commonly known as "gum trees"("bloekoms" in Afrikaans) in South Africa.
The successful sequencing of this genome has been published in the prestigious, high-impact scientific journal Nature (advanced online publishing at 19h00 London time on 11 June 2014;, print edition 19 June 2014).
"Now that we understand which genes determine specific characteristics in these trees, we can breed trees that grow faster, have higher quality wood, use water more efficiently and will cope better with climate change," Prof. Myburg explains the significance of this major scientific milestone. "Even more, we can turn well-managed Eucalyptus plantations into bio-factories to produce specific kinds of sought-after materials and chemicals."
He added: "With this new knowledge about the molecular basis for superior growth and specific adaptations in plants, we can apply the same techniques to other woody plants that can be used as feedstock in the bio-economy of the future."
Gum trees are highly adaptable and grow exceptionally fast. While native to Australia, these trees are planted worldwide, mainly for timber, pulp and paper production, but increasingly also for "chemical cellulose" – a form of pure cellulose that is used in a wide variety of industrial products from textiles to pharmaceuticals.
The project to sequence the Eucalyptus grandis genome involved 80 researchers from 30 institutions across 18 countries. It took them five years to sequence and analyse the 640 million base-pair genome. Combing through the more than 36 000 genes found in Eucalyptus, the researchers homed in on those that may be able to boost the economic value of the trees by influencing the production of cellulosic raw materials that can be processed for pulp, paper, biomaterial and bio-energy applications.
"As one of the lead organisations, the University of Pretoria is delighted with the positive outcomes of the project and the exciting new opportunities for our genomic research programmes," says Prof. Anton Ströh, Dean of the Faculty of Natural and Agricultural Sciences at UP.
Prominent co-leaders on the project include Prof. Dario Grattapaglia of the Brazilian Agricultural Research Corporation (EMBRAPA) and Catholic University of Brasilia; Dr Gerald Tuskan of the Oak Ridge National Laboratory (ORNL) and the BioEnergy Science Center (BESC) and US Department of Energy Joint Genome Institute (DOE JGI); Prof. Dan Rokhsar of the DOE JGI; and Dr Jeremy Schmutz of the DOE JGI and the HudsonAlpha Institute for Biotechnology.
The US Department of Energy was a major funder via its Joint Genome Institute in Walnut Creek, California, where most of the DNA sequencing was done.
South Africa's Department of Science and Technology (DST), together with forestry companies Sappi and Mondi, supported Prof. Myburg and his team by funding the construction of the genome map used as a scaffold for genome assembly, as well as the sequencing of expressed genes used for annotation of the genome.
"The development of new knowledge and skills in tree genomics, and the application of that knowledge to enhance industry competitiveness, is directly aligned with the DST's vision of a bio-economy," says Dr Phil Mjwara, Director-General of the Department of Science and Technology. "This is a superb example of full value-chain thinking, and thus an important investment for the Department."
Prof. Myburg's research team identified genes encoding 18 final enzymatic steps for the production of cellulose and the hemicellulose xylan, both carbohydrates that are enriched in wood fibre cells and can be used for biofuel production. "By tracing their evolutionary lineages and expression in woody tissues, we defined a core set of genes for biopolymer production that are highly expressed in the development of xylem – the woody tissue that helps channel water throughout the plant and strengthens the tree," he explains.
Team members Dr Carsten Külheim and Prof. Bill Foley at the Australian National University (ANU) also found that, among sequenced plants to date, Eucalyptus showed the highest diversity of genes for specialised metabolites such as terpenes. These hydrocarbons serve as chemical self-defenses against pests, and also provide the familiar aromatic essential oils used in medicinal cough drops and in industrial processes.
Among the family of terpene compounds naturally produced in plants – and in particularly high abundance in Eucalyptus trees - derivatives of sesquiterpenes that contain 15 carbon atoms (diesel fuel typically contains 10 to 24 carbon atoms) may be promising alternatives for petroleum-based fuels. Researchers have already made important breakthroughs in engineering aspects of terpene biosynthesis into microbes such as bacteria and yeasts.
"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," Prof. Myburg says. "In future, jumbo jets may take off powered by renewable, Eucalyptus-based fuel!"
Photos:
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Prof. Zander Myburg, as well as plantations, trees and wood in South Africa:https://www.dropbox.com/sh/026wsnxz8xre4dl/AADLQrVPNWhnLJklZ49F8Nrta -
Flickr album with images/captions of collaborators abroad:https://www.flickr.com/photos/doe_jgi/sets/72157644739719441/
To interview Prof. Zander Myburg, please contact:
Nicolize Mulder (University of Pretoria)
Tel: 012 420 3023
Cell: 083 709 3041
E-mail: nicolize.mulder@up.ac.za,
or email Prof. Myburg directly at:
E-mail: zander.myburg@up.ac.za
Cell: 083 389 0325
Notes to editors
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Prof. Myburg is the director of the Forest Molecular Genetics Programme in the Department of Genetics, University of Pretoria. -
The paper may be cited via the following digital object identifier (DOI) number: 10.1038/nature13308. Once the paper is published electronically (11 June, 18:00 London time), the full text can be retrieved from the Nature web site at this URL: http://dx.doi.org/10.1038/nature13308 -
The Eucalyptus genome data are available publically through the DOE JGI’s comparative plant genomics portal known as Phytozome, now in its 10th revision (http://phytozome.jgi.doe.gov/pz/portal.html#!info?alias=Org_Egrandis). -
A short interview with Dr Gerald Tuskan on the implications of the team's Eucalyptus genome analysis can be viewed here: http://bit.ly/Tuskan-EucalyptusEucalyptustrees are commonly known as "gum trees", but in South Africa the wood is often sold as "saligna", due to the early (decades ago) misidentification of eucalypt trees in South Africa as the sister species Eucalyptus saligna. The well-known "blue gum" is a different species, Eucalyptus globulus. -
More than 500 000 hectares of Eucalyptus plantations are cultivated as timber and fibre crops in South Africa – accounting for about 40% of the country's forestry plantations. The rest is pine and wattle. Although eucalypts are on only 40% of the plantation land, they grow much faster and produce more than 50% of the wood products, including pulp and paper. Forestry products contribute about R21 billion per year to South Africa's GDP, of which R15 billion is from exports. Around 165 000 people are directly or indirectly employed in South Africa's forestry sector (data source: http://www.forestry.co.za/statistical-data/). -
More information about novel biofuels:
o High-performance aviation fuels from terpenes (http://arpa-e.energy.gov/?q=arpa-e-projects/high-performance-aviation-fuels-terpenes)
o New Biofuel Could Replace Today's Standard Fuel for Diesel Engines (http://oilprice.com/Alternative-Energy/Biofuels/New-Biofuel-Could-Replace-Todays-Standard-Fuel-For-Diesel-Engines.html)
o Joint BioEnergy Institute Scientists Identify New Microbe-Produced Advanced Biofuel as an Alternative to Diesel Fuel (http://newscenter.lbl.gov/news-releases/2011/09/27/jbei-scientists-identify-bisabolane-as-an-alternative-to-diesel-fuel/
