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Dandelions for more sustainable rubber

Categorie(s): Agriculture, Biotechnology, Sustainable projects

Researchers and start-ups are nourishing the roots of a sustainable alternative to the rubber tree

 Cornish and her group at Ohio State’s College of Food, Agricultural & Environmental Sciences are growing a special variety of dandelion from Kazakhstan known by the scientific name Taraxacum kok-saghyz. They’ve renamed it ‘Buckeye Gold’. It looks very much like the dandelions that grow wild in the U.S.  and Europe. But unlike those backyard weeds, its roots contain 10–15% natural rubber.

Dandelion rubber’s quality and performance are nearly identical to that produced by Hevea rubber trees grown in Southeast Asia.

Turning dandelions into an industrial rubber crop will require further trait development to make it easier to grow and higher yielding. European researchers and companies are also working on improved varieties and processing technologies. They all share the same goal: finding a nontropical alternative to the venerable rubber tree.

People have been looking for an alternative rubber producing plant ever since Henry Ford: dandelions, goldenrod and sunflower. Whenever war, weather or disease makes natural rubber expensive, people start looking for alternatives. But the crises never last long enough for a new crop to gain a toehold.

Now, dandelion rubber proponents say long-term concerns about prices , sustainability and labor availability are strong enough to develop dandelion rubber seriously. Trees on rubber plantations in south east Asia take years to grow to maturity. Production can’t quickly respond to changes in demand. Meeting growing Asian demand for rubber will require clearing rain forest to expand plantations. And the price for hand-harvesting and shipping rubber around the world continues to rise.

Rubber from dandelions is technically viable, but it is not yet clear if the crop has commercial potential. Only 10–15% of the plant is rubber, so more work must be done to find by-product applications to reduce the waste. Much of that waste is inulin, a polysaccharide that is being used in dietary fiber and prebiotic applications.

For a real good crop next-generation dandelions shlould have some special traits: inability to cross-pollinate with native plants, ability to withstand weed and pest control and resistance to disease. It’s a tall order. But dandelions, like most weeds, have lots of genetic variety to work with. And gene-editing techniques such as CRISPR/Cas9 may speed up the process. “In history, establishing crops took thousands of years. We are trying to compress the time schedule as much as possible,” Cornish says.

She has shown that CRISPR/Cas9 gene editing makes it possible to increase the rubber content of the plant by decreasing the competing energy storage pathway that forms inulin. Her next task is to insert genes for herbicide resistance.

In the Netherlands, researchers at Wageningen University are working on varieties that will produce thicker roots to increase rubber output. The current limit of about 200 kg per hectare.

Durable tires

Tires are the biggest users of natural rubber, consuming 70% of the world production, which is concentrated in Thailand, Malaysia and Indonesia. A tire manufacturer has now demonstrated that latex from dandelions is strong enough to make durable tires. Their grip on wet roads could even be better than that of conventional tyies.

In addition to tires, natural rubber is also used for surgical gloves and tubing for medical applications. It is deployed in construction for wall cladding, roofing, flooring, sealing and in adhesives and coatings. All in all, more than 40,000 products are made from natural rubber.

Inulin for PET bottles

In addition to rubber, the EU project also aims to produce inulin from the dandelion. Once the rubber is extracted, the plant contains 40% cent inulin, a low-calorie sweetener that is currently produced from chicory. This sugar molecule is processed by the food industry in syrups and added to yogurt drinks as a prebiotic. “But this is a small market,” Van der Meer (the scientist in Wageningen University) underlines. “We prefer to split the fructose polymer for conversion to furan chemicals. These can, for instance, be used to make biodegradable plastic bottles – a much larger market.”

The combination of latex and inulin make cultivation of Russian dandelion economically attractive

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Dandelion rubber offers good qualities but brings several unknowns:

Pros
▸ Can be grown in northern regions
▸ Yields high-quality rubber
▸ Harvest can be automated
▸ Potentially sustainable
▸ Can quickly meet spikes in demand
▸ High genetic diversity

Cons
▸ Unknown cost of production
▸ Unknown pest, disease risk
▸ No easy way to control weeds
▸ No government support for growers
▸ Huge volume required for use in tires
▸ May lose support in times of low rubber prices


Dandelion researchers are also working on better processes to get the rubber out of the plant. To start, the roots are harvested using standard farm machinery, then cleaned, dried, and ground up. Cornish and Swiger have separately patented processes for separating the rubber from the inulin fiber. Ohio State has a processing plant where it uses water to extract liquid latex rubber as well as rubber solids.

Source: C&EN (chemical and engineering news) and Wageningen University &research