Sugarcane genes tweaks target a bio-fuelled future
Researchers are using genetic tools to reprogram sugarcane, constructing its fibres so they can be more easily broken down for use in new world of renewables.
By Melissa Marino
There’s a transformation underway for sugarcane in Australia. It is the quintessential Queensland crop, steeped in the Australian psyche and economy through popular culture and more than 150 years of cultivation. But before too long, sugar may not be its primary output.
In a world increasingly looking to alternatives to fossil fuel, the use of sugarcane in the production of biofuel is growing. But beyond this, scientists are also unlocking the potential for sugarcane as a 100 per cent recyclable bioplastic – a substitute for petroleum in the production of countless items from cosmetics to carpets to car parts.
“It’s about reinventing sugarcane as a crop with a wider range of end uses,” says Queensland Alliance for Agriculture and Food Innovation (QAAFI) director Robert Henry, who as Professor of Innovation in Agriculture is on the frontier of this work. “The sugarcane industry can produce sugar but it can also produce other things like electricity, biofuels for transportation and oils to replace traditional plastics.”
Professor Henry and his colleagues at the University of Queensland’s QAAFI are working on sequencing the sugarcane genome as part of a US Joint Genome Institute project. Much larger than the human genome, it is the last of the 20 major crops to be sequenced due to its complexity. Nevertheless, with DNA science continuing to improve, Professor Henry expects to see “the mighty sugarcane” decoded by 2020.
Combined with extensive field trails, the research is pinpointing which genes are responsible for which traits and furthermore, how genetic variation influences a plant’s composition and performance. These insights can then be used in breeding for specific outcomes such as maximising sugar production but also increased fibre or a fibre composition that is more easily broken down for conversion into biofuel or oils for plastics.
“It’s about deconstructing the plant – looking at all the things in the genetics that contribute to the structure of the plant material that leads to it working better in those processes,” he says.
Ultimately Professor Henry would like to see a level of versatility where varieties can be quickly bred and grown to suit different market conditions. This would allow growers to maximise the value of their crop and cope with fluctuating sugar prices by targeting different markets – whether it be food, fuel or plastics –at different times.
A falling sugar price, driven by declining demand in world markets and increased competition from India and Brazil, is one of a confluence of events making alternative end-uses more attractive for Australian producers.
Consumers and industry are also increasingly looking to alternatives to fossil fuels for power, transport and in the production of plastics. This provides new commercial opportunities for renewables.
The science is quickly developing to a point that will allow growers to take advantage of these opportunities, through the development of new varieties tailored for a particular function whether it be sugar, biofuel or bioplastics production.
“The technology advances and the needs are coming together and we really have the opportunity to do something in the relatively near-future,” Professor Henry says.
While sugar mills already burn bagasse (the fibrous residue that remains after juice is extracted from sugarcane stalks) to produce the energy for their milling operations, scientists are taking things further.
Supplying energy to the domestic electricity market is one possibility and genetic improvements to more efficiently convert the bagasse into low value sugars, and subsequently ethanol, will provide more options. “If we can turn those mountains of bagasse into a high value product then we have got a very attractive proposition from an industry point of view,” Professor Henry says.
To further this aim QAAFI has teamed with US Joint BioEnergy Institute and Sugar Research Australia as part of an Australian Research Council Linkage Project, testing a range of sugarcane varieties with different chemical compositions to understand which types produce ethanol most effectively and efficiently.
Meanwhile, in Delhi, with the Indian Institute of Technology, researchers are investigating processes to most efficiently break down lignin (a complex part of the fibre in the sugarcane bagasse) into an aromatic chemical compound used in the production of plastics. Drink bottles made from a sugarcane bioplastic are just one product on the agenda from this QAAFI collaboration.
“Those sorts of products are quite possible, it’s just all about the economics of doing it. Key to this is how suitable we can make the starting material for these processes, and that’s how the genetics can make these products commercially realistic,” he says.
Insights gained from the partnerships are being fed back into Professor Henry’s breeding program to ensure varieties are developed with traits suitable for end markets.
Several target genes have been identified, and the first gene-editing experiments planned aim to tailor sugarcane to more effectively produce biofuels and bioplastics.
For biofuels, this includes producing a higher yield of fermentable material from the bagasse. For bioplastics, it requires altering the composition of lignin so it breaks down more easily.
These molecular level changes will help make production of sugarcane biofuels and bioplastics more efficient and competitive in a market dominated by fossil fuels. “And that’s what all the genomics work is largely about,” Professor Henry says. “It’s working out how we can get more efficient conversion, higher yields of products and higher value products.”
Sugarcane, he says is ideal for the production of renewables because it is fast-growing with abundant biomass and has sophisticated processing systems already built around it.
“We grow a very large amount of sugarcane per hectare and producing that much biomass and capturing that much carbon from the atmosphere and turning it into plant material is done very efficiently by the sugarcane plant. That is a key thing if we’re trying to produce renewable materials from plants,” he says.
Diversification of the crop to help meet the global need for fossil fuel alternatives in transport and plastics will help Australian sugarcane industry to remain viable.
“Really sugarcane globally needs to make this transition from being just a sugar crop to being a crop with a wider range of uses if its going to have a long-term future,” he says.