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Mint, DNA Sequencer, Irrigation Info

Posted by | February 1, 2012

Using Science to Rescue a Wilting Mint Industry

Peppermint growing in the Pacific Northwest.
Peppermint growing in the Pacific Northwest. Photo by Brian Charles Clark/WSU.

Although Washington is the largest peppermint producer in the United States, this status is being challenged. So too is the U.S. share of the global mint oil market, which has slipped from a position of dominance to under 50 percent from the flood of synthetic and different-quality oils produced in China and India. The flavor of chewing gum, candy, and toothpaste may be forever changed.

“It’s truly a crisis situation,” said Mark Lange, an associate professor in the Washington State University Institute of Biological Chemistry. Another culprit threatening the industry is verticillium, a type of fungus that causes “wilts” in peppermint due to reduced water and nutrient flow from a blockage in the plant’s vascular tissue. As with many diseases caused by fungal agents, there is no chemical treatment. Once soil is infected with verticillium, peppermint can’t be grown there.

“It’s similar to the plight papaya growers in Hawai’i were faced with 10 or so years ago,” Lange said. Ringspot virus threatened to wipe out the papaya industry. The only hope was to use science to transform the valuable crop into one that was also resistant to the virus. And that’s precisely what scientists did. By introducing a protein that blocks the virus’s attack on the plant, researchers were able to, in effect, vaccinate papaya. Today, the Hawai’ian papaya industry is thriving.

Mark Lange
Mark Lange

Lange and his colleagues are attempting something similar with mint. In order to survive in the United States, growers need a plant that produces an essential oil with the flavorful complexity of peppermint but that has resistance to verticillium. Classical breeding techniques won’t work with peppermint because it is a sterile hybrid and produces no seed. With no seed, there is no genetic variation to manipulate through crossbreeding, as humans have done with plants and animals for thousands of years. And with no chance of crossbreeding, the hope of finding a peppermint plant with verticillium resistance is nil.

Lange and his team are pursuing the most viable alternative by working with a type of mint that is resistant to the verticillium fungus and coaxing it to produce an oil of peppermint-like depth and complexity. “The mint we are working with is slightly different from peppermint but has mostly the same genetic components. So we are modifying it to produce the quality and quantity of essential oil that producers need to be economically competitive. If we don’t put this transformed plant into commercial production, we will lose the complexity of the flavor of peppermint.”

Lange pointed out that, unlike transformation of corn or soybeans, engineered mint cannot reproduce, so there is no chance of it spreading and interbreeding with wild types of mint. “The product is a distilled oil. The oil contains no genetic material, and the plant material is destroyed in the distillation process.” To distill the oil from the plant, the chopped plants are subjected to heat and pressure. The distillation takes place on the farm so there are no silos or other gathering points where contamination might take place.

–Brian Clark

Learn more about the cutting-edge plant science being conducted in WSU’s Institute of Biological Chemistry by visiting

New DNA Sequencer Speeds Research

Genomicist Amit Dhingra is featured on a tongue-in-cheek magazine cover designed by student Ken Dorrance. Dhingra and other WSU researchers now have access to one of the fastest, most powerful DNA sequencing machines in the world.
Genomicist Amit Dhingra is featured on a tongue-in-cheek magazine cover designed by student Ken Dorrance. Dhingra and other WSU researchers now have access to one of the fastest, most powerful DNA sequencing machines in the world.

WSU is among the first in the country to acquire a DNA sequencing machine that will let researchers across the university assemble and characterize genomes with dramatically improved speed and accuracy. The technology promises to enhance researchers’ understanding of the genetic blueprints of plants and animals and open new avenues for fighting diseases and improving the productivity of crops.

“This catapults our faculty into a unique and enviable position,” said Howard Grimes, vice president of research, whose office funded the $774,000 machine. “We expect this to drive our research programs into new territory extraordinarily quickly.”

Grimes said WSU is the nation’s first agriculture-veterinary medicine university in the country to acquire the Pacific Biosciences technology, which is up and running in the WSU Laboratory for Biotechnology and Bioanalysis.

The PacBio RS single molecule real time sequencer is effectively “a big laser with a really good camera,” illuminating and identifying thousands of a DNA molecule’s individual nucleotides at a time, said Derek Pouchnik, lab director. By decoding long sections of DNA that can later be pieced together, it will enable researchers to fathom “the cast of characters in a cell,” said Mark Wildung, senior scientific assistant in the lab. “It’s hard to work with an organism anymore without understanding the genome,” he said.

Possible applications include:

  • Sequencing the genomes of crops with an eye toward isolating genes responsible for disease resistance, greater productivity, and drought tolerance.
  • Decoding the genes of germs central to infectious diseases.
  • Finding enzymes that fungi use to crack cellulose, a major area of focus in developing a cost-effective biofuel from woody plants.

Horticultural genomicist Amit Dhingra, who led a team that in 2010 published the genome of the golden delicious apple, said the PacBio machine’s large gene sequences will help researchers piece together the genomic puzzle more efficiently. It also will complement other sequencing technologies at WSU. Already, he said, researchers are using the equipment to get new genetic information about apples, pears, and sweet cherries.

With a full suite of sequencing technology, said Dhingra, “we will have a much clearer image of what novel genes underlie the unique biology of these plants. Then we can find ways to make fruit trees productive sooner and how to make our crops fix carbon more efficiently to address burgeoning food and fuel demands.”

–Eric Sorensen

Watch a short video describing the possibilities the new sequencer makes possible by visiting

WSU Extension Launches Irrigated Agriculture Information Service

Center pivot irrigation system in eastern Washington. Photo courtesy J. Brew/brewbooks via Flickr.
Center pivot irrigation system in eastern Washington. Photo courtesy J. Brew/brewbooks via Flickr.

Water management is a key issue for all agricultural producers, said Andy McGuire, a WSU Extension educator based in Grant County. Wise use of this precious resource not only improves producers’ economic bottom lines, but also reduces dust in cities and the loss of valuable soil.

That’s why a team of WSU Extension experts launched the Irrigated Agriculture Information Service. The new system is based on a user-defined set of interests to email alerts and other customized information. Users can now choose from over 35 topic areas ranging from apples to cattle production and from drip irrigation to wine grape growing. Once users create an account and set up topic preferences, they can log back in at any time and change their options.

“We want to provide members of the irrigated agriculture industry with only the information they want, when and where they need it,” said Andy McGuire. “We want to get research results and other information out as quickly as possible to those that use it on a daily basis. This system replaces an older print-based information-delivery system. That not only saves money, it expedites the delivery of specific information to specific audiences. Email gives users the ability to receive timely water management information at home, in the office, or on a smart phone.”

Alerts will be topic specific, McGuire said. For instance, WSU’s pest-monitoring team will quickly notify potato growers when crop-damaging insects are spotted in potato fields. “Timely information helps growers be judicious about pesticide use, thus improving overall water quality.”

The new system is available at

–Brian Clark