Sunflower rubber research expands with new funding

ST. LOUIS—Sunflower fields aren't just for photo opportunities.

David Woodburn, CEO of Edison Agrosciences Inc., has high hopes for developing technology aimed at increasing the natural rubber content in sunflower plants. His company now is armed with a new bushel of funding to help.

Sunflowers contain small amounts of natural rubber in their leaves, and Woodburn and his company are working to increase the yield through genetic modification. It's a project that could help the U.S. become more independent for its natural rubber supply, which currently is chiefly harvested in just one part of the world.

When it comes to natural rubber, hevea brasiliensis—the rubber tree—is the world's titan, and production overwhelmingly is concentrated in Southeast Asia.

But Woodburn and Edison have a different idea.

"The plants themselves, without any improvement or modification, produce about 0.2 percent to 1.6 percent of their leaf weight in natural rubber," he said about sunflowers.

While that doesn't sound like a lot, doubling, tripling or even quadrupling the output through genetic modification could lead to a viable business opportunity on U.S. soil, Woodburn said. "That's what we're doing. We're just trying to increase the amount of natural rubber already being produced in these plants."

There already are other efforts under way in the U.S. to return commercial natural rubber production to domestic soil decades after the country did just that during World War II.

Guayule, a shrub that grows in the Southwest and Mexico, is considered a potential candidate for increased rubber production. That's what was used during the war when Southeast Asia rubber supply chains were choked off by Japan.

Because guayule provides rubber during emergency times, research now is heating up to make that source viable during today's economic conditions. Dandelions also are viewed as a potential domestic source of natural rubber as research continues on those plants.

Edison is being boosted in its efforts with the recent award of an additional $1 million in grant money from the Defense Advanced Research Projects Agency (DARPA), part of the U.S. Department of Defense. This is a phase two grant from the agency that continues the work that DARPA initially funded through a $225,000 grant.

Blake Bextine is a program manager for DARPA and sees what he calls a "ton of potential" in sunflower rubber development.

"Our natural rubber supply depends on a single plant (rubber trees) that are grown outside of the U.S. The cropping system used still depends on rudimentary methods of latex collection so harvesting is time intensive," he said in an email interview.

"With the sunflower, we have an opportunity to transition to a domestically grown crop that could fit into a traditional, high-yield agricultural cropping system. This would reduce our dependence on an external source of natural rubber that is susceptible to fluctuation in supply because of environmental impacts due to weather, pests and pathogen damage," Bextine said.

The initial DARPA grant is for two years, but there is an opportunity to extend the funding for another year and an additional $500,000.

"A million dollars can go pretty quickly over two years. We continue to work with sunflower in the lab to try different combinations of our biotechnology on the plants to see if it makes a difference at all in the amount of rubber, the type of rubber that's produced," Woodburn said.

The new funding also will allow some small field trials on varieties of sunflowers to compare the rubber output of those outside plants with those grown in a greenhouse environment.

Researchers will dive deeper into genetic modification of sunflower seeds in an effort to boost rubber production. That potentially can include efforts to "turn on more rubber or turn off the brakes, so to speak, on whatever holds back the plant from producing more rubber," he said.

The company also is doing full genetic sequencing of sunflower varieties to see if they can find clues regarding why some plants produce more or less rubber.

Woodburn sees work to find alternative sources of natural rubber as imperative because the industry faces the potential of a "rubber apocalypse."

"It sounds kind of silly, but there are thousands of products made from natural rubber that we interface with every day. All of that comes from the hevea rubber tree," he said.

The species was wiped out in South America due to disease, and Woodburn said the potential exists for that to eventually happen in Asia. "At that point, the only thing you can do is A: Look for an alternative crop or B: Deforest tons of rainforest in Africa and expand production there.

"There is seriously a risk to the world's supply of natural rubber," he said. "When you apply logic to what has the most potential in terms of an alternative crop, it's not dandelion, it's not guayule desert shrub. It's probably an already cultivated crop called sunflower. We know how to grow it. We know we have the seed infrastructure for it. We even know what fertilizer and chemical treatments to use on it. The only difference is improving the plant and developing the extraction capacity to do that," Woodburn said.

Edison will continue work in the company's laboratory as well as with the nearby Donald Danforth Plant Science Center in St. Louis on the project.

"Edison presented a vision that combined fundamental discovery that would lay the foundation for sunflower as a viable natural rubber source and also short-term research goals that would demonstrate feasibility. This diverse approach was well received," Bextine said.