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Cuphea - plants with a beautiful future.

Cuphea - Plants With a Beautiful Future

The pink, red, and purple-flowered cuphea (coo-FEE-ah) plant may one day add a splash of color to the golden corn tassels and lavender soybean blooms that dot midwestern fields each summer.

ARS scientists hope to domesticate the plant, which grows wild in North, Central, and South America. Some species, members of the Lythraceae plant family, have already been released as ornamental ground cover for urban settings in the southeastern United States.

Once modern biotechnology taps the genetic diversity of cuphea and domesticates the plant - admittedly a long-term and high-risk undertaking - farmers should have a ready market for the seed it produces, says William W. Roath, an ARS agronomist at the North Central Regional Plant Introduction Station, Ames, Iowa.

Roath is curator of a collection of about 400 cuphea strains representing 90 of some 250 species believed to exist. He collected many of the strains in Brazil, working with scientists of that nation's germplasm resources laboratory.

Early this fall, he plans to explore for more species in southern Mexico, along with scientists of Mexico's National Herbarium.

Cuphea seed oil contains large amounts of fatty acids, such as lauric and capric acid, that help give soaps and detergents their cleaning power. Capric acid, a foam-stabilizing component in dessert whips, also shows promise for expanded use in medical, nutritional, and dietetic applications.

Currently, the U.S. soap and detergent industry gets about half of these fatty acids from petroleum. The other 50 percent comes from coconut and palm kernel oils. In an average year, the 500,000 tons of imported oil cost about $300 million.

Fluctuations in the price and supply of coconut and palm kernel oils are just one reason for developing cuphea as a U.S. crop, says Roath.

Cuphea oil's high certain fatty acids also makes it preferable to tropical oils. Coconut oil is 45 to 50 percent lauric acid while some strains of cuphea produce an oil that contains nearly 80 percent of the fatty acid.

ARS, the Oregon State University Agricultural Experiment Station, and member companies of the Soap and Detergent Association are working to develop cuphea's potential as a crop plant. The joint program began in 1984.

The work could pay off in just a couple of decades, instead of the centuries it took to develop other crop plants, Roath says, "because we have the tools of modern science."

Scientists are aiming for a seed production yield of 1 ton per acre. But first, researchers have to tame some of the wild traits that may be detrimental to a cultivated crop. For example, cuphea seed is difficult to harvest because it typically shatters easily from the pod and develops and ripens unevenly over a long time.

Moreover, seed dormancy makes establishing a crop stand unreliable. Few seeds germinate the first year; others may germinate years later.

Overcoming this dormancy has been a painstaking, yet necessary task to quickly grow seed needed for research projects. To do this, Roath removes the seed coat, germinates the seed on wet paper, and transplants the seedlings.

However, Steven J. Knapp, a plant geneticist at Oregon State University in Corvallis, has found a less tedious method to get similar results. He crosses strains of C. viscosissima with C. lanceolota, a species less prone to dormancy, to get fully fertile hybrids.

Roath believes that C. viscosissima holds the most promise for midwestern agriculture because of its adaptation in the wild to midwestern conditions. Interspecific hybridization - crossing species - is one procedure to assist in developing the plant for cropping because, so far, little genetic variation has been found.

Until 1987, the Plant Introduction Station had only three accessions of C. viscosissima from Missouri, Virginia, and West Virginia. Then Roath, and horticulturist Mark P. Widrlechner at Ames, added 77 more grown from seed they had collected in a 300-mile-wide area stretching from eastern Kansas to western North Carolina and Virginia.

Chemists Robert Kleiman and Bliss Phillips at the USDA National Center for Agricultural Utilization Research, Peoria, Illinois, helped evaluate the cuphea lines. Although genetic variability is less than researchers had hoped, there were some differences in seed size, yield, and oil content and composition that may one day be exploited to produce crop varieties.

Tests indicate that the C. viscosissima lines are rich in caprylic and capric acid, but low in lauric acid - around 4 percent. Both capric and caprylic acids are used in specialized clinical diets to alleviate digestive disorders.

Scientists believe that it may be possible to increase the lauric acid content through mutations. To induce these changes, Knapp is treating plants with chemical mutagens while graduate student Hamadi Ben-Salah at Iowa State University is searching for the mutations among tissue cultures. ISU graduate research assistant Weiping Chen is working with Roath and ISU biochemist Basil Nikolau to develop biotechnological approaches to tap the genetic diversity of cuphea.

Other hopes for increasing lauric acid lie in crossing C. viscosissima with other species.

To help identify plants with desired traits among the accessions of C. viscosissima and other species, Chen is searching for enzymes that might serve as genetic markers for those traits.

Traits that seem common among cuphea species include resistance to diseases and insects. But ARS entomologist Richard L. Wilson of the Plant Introduction Station says insect problems may arise when cuphea becomes a widely grown crop. So far, he's seen one possible pest - the larvae of the whitelined sphinx moth - crawling on cuphea plants.

Cuphea growers and landscapers may be pleased to find the plant provides some measure of protection against erosion. At Tifton, Georgia, ARS soil scientist Casimir A. Jaworski has identified selections of C. llavea and C. glutinosa that overwinter well in the southeastern United States and provide especially good ground cover as spread by rooting of shoots, by underground stolons, and by seeds.

Jaworski and his colleagues have developed four ornamental cuphea plants suitable for the southeast United States. Three of the selections in C. glutinosa have been named Lavender Lady, Lavender Lei, and Purple Passion. A single selection of C. llavea has been named Georgia Scarlett.

PHOTO : Inside a growth chamber, agronomist William Roath examines Cuphea viscosissima.
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Title Annotation:industrial applications of Cuphea
Author:Hardin, Ben
Publication:Agricultural Research
Date:Sep 1, 1991
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