Genetically fingerprinting the plant material used to prepare St. John's-wort can guarantee consumers that they are getting their money's worth of this herbal product. St. John's-wort is a widely used dietary supplement that is popularly taken as an antidepressant. Various species of the genus Hypericum contain many of the chemical constituents of St. John's-wort, but only the flowering tops of H. perforatum are supposed to be used in its preparation. Today, adulteration of commercial preparations often occurs, due mainly to the use of species other than H. perforatum. ARS scientists developed a molecular technology that uses genetic markers to reveal the identity of the plant material. Using these markers, they were able to detect contamination in seed packages sold as H. perforatum. This was possible because differences among the DNA sequences of the various Hypericum species can be detected in the form of genetic fingerprints. The continued public acceptance of herbal dietary supplements largely depends on the ability of manufacturers and regulatory agencies to ensure that botanical preparations are safe and appropriately labeled. In the current regulatory environment, the safety of herbal products is tightly linked to the positive identification of their ingredients. ARS scientists developed the technology in response to the Food and Drug Administration's request for means to guarantee the authenticity of St. John's-wort.

Natural Products Utilization Research Unit, Oxford, MS
Camilo Canel, (662) 915-7965, canel@oldmiss.edu

Genes needed for breeding superb new lesquerella plants for tomorrow might be easier to find, thanks to a simple new technique for extracting genetic material from this hardy native perennial. Oil from Lesquerella fendleri could reduce America's reliance on imported castor oil needed for lubricants, coatings, plastics, paints, lipstick, shampoo, and other products. To find genes that would enable tomorrow's lesquerellas to flourish on salty soils or to yield higher quantities of oil, for instance, scientists must decode the plant's genetic material. But procedures used successfully in biotech labs worldwide to coax DNA from other plants haven't worked with lesquerella. That's because its natural gums, or polysaccharides, form large pellets that firmly trap DNA inside. Now, a procedure from ARS scientists sidesteps this sticky problem by putting ground-up leaf tissue through a series of simple steps, including 10-minute and 15-minute spins at low or moderate speeds on the centrifuge. The procedure, adapted from an approach developed elsewhere in 1983, takes about as much time as conventional techniques for pulling out plant DNA—yet doesn't require harsh solvents. What's more, the new method might be ideal for extracting DNA from other high-polysaccharide plants like peanuts, cucumbers, or muskmelons. A member of the mustard family, lesquerella is native to Arizona, New Mexico, Colorado, Utah, Texas, and Mexico.

U.S. Water Conservation Laboratory, Phoenix, AZ
David A. Dierig, (602) 379-4356, ext. 265, dierig@uswcl.ars.ag.gov

Flooding injuries to soybeans have been found to be caused by a buildup of carbon dioxide—not by a lack of oxygen in waterlogged soils, as previously thought. This discovery by an ARS scientist has led to a greenhouse test to aid breeders in selecting flood-tolerant varieties. It screens soybean seedlings for flood tolerance based on their response to a 30-percent carbon dioxide (CO₂) solution. Nontolerant soybeans either stop growing or die, while tolerant soybeans show less signs of injury. In the field, CO₂ concentrations in air trapped in waterlogged soils were found to be as high as 50 percent; soybean yield losses became significant after exposure to 30-percent concentrations. For the new test, seedlings are placed in plastic pouches and dunked in a nutrient solution through which CO₂ is bubbled. A prototype system is being tested that uses special cameras to sense plant reactions to high CO₂. These reactions include drooping leaves, less root and shoot growth, and a yellowing that eventually deteriorates to black spots as tissue dies. When fully automated, the system could screen thousands of seedlings in a few weeks.

Soil Drainage Research Unit, Columbus, OH
Tara T. VanToai, (614) 292-9806, tvantoai@magnus.acs.ohio-state.edu

A DNA marker that can help breeders select flood-tolerant soybeans has been found. The marker is near genes that make soybean plants so flood-tolerant that they yield 50 percent higher after flooding than nontolerant plants. In both 1997 and 1998, 280 soybean lines were field-tested, growing in completely waterlogged soils for 2 weeks at the flowering stage. The work is being done jointly by ARS scientists and colleagues at the University of Arkansas-Fayetteville, University of Utah-Salt Lake City, and Ohio State University-Columbus. The scientists are also part of a national soybean genome mapping project partly funded by the United Soybean Board. For confirmation of the yield increase in the field, selected plants having the marker will be field-tested in Arkansas and Ohio. Field and greenhouse tests are being used to find germplasm lines containing additional genes that may account for further yield increases in flooded fields.

Soil Drainage Research Unit, Columbus, OH
Tara T. VanToai, (614) 292-9806, tvantoai@magnus.acs.ohio-state.edu

ARS scientists have found the largest number of new Penicillium species discovered by any person or group since the genus was first described in 1809. They accomplished this by sampling molds where penicillia are usually not sought—and by using modern biotechnological tools. Until now, researchers have focused mainly on Penicillium from moldy food, moldy livestock feed, and soil samples. Working with a collection of 600 molds that parasitize wood-decaying fungi, scientists found 39 Penicillium species new to science. To confirm that they were new, the researchers used an automated DNA sequencer to compare the particular sequences of genes in the molds with sequences in archived penicillia. Then they added the new species to the ARS Culture Collection's 102 previously known Penicillium species, including those that scientists used to help launch the antibiotics industry a half century ago. The addition of new species to the collection will help scientists learn more about the genus from which penicillin is obtained. And by using gene sequence information to improve identification and comparison, the researchers are better equipped to find more useful Penicillium isolates from nature.

National Center for Agricultural Utilization Research, Peoria, IL
Stephen W. Peterson, (309) 681-6384, peterssw@mail.ncaur.usda.gov

Jade peas, or edible vegetable soybeans, can be eaten just like green peas. Now, a new type of jade peas called BARC-18 can give farmers a crop they can tailor to their individual taste, needs, and growing conditions. ARS geneticists bred a vegetable soybean to a vigorous, tall-growing forage soybean to develop BARC-18. It provides soybean growers with source material for developing their own vegetable-type soybean of superior vigor for a variety of local conditions. Vegetable and soybean growers can use BARC-18 to develop their own, unique lines. BARC-18 produces a wide variety of plant types—tall and short, large and normal-size seed, early- and late-maturing, green seeds, and yellow or pale-cream seeds. Growers can select plants with suitable characteristics and preferred eating qualities after they grow selections of the plants for three generations. To cook jade peas, just boil them for about 3 minutes, pop them from their pods and season to taste. Seeds of BARC-18 have been sent to more than 25 growers, along with detailed instructions on growing and selecting offspring, preparing the soil, and cooking the beans. BARC-18 has genes for exceptional plant height and vigor, large seed size, green seed coat, and green embryo. It also has genes for resistance to lodging—toppling over as a result of wind or rain. The scientists developed BARC-18 by crossing the vegetable-type soybean Verde with several forage-type soybeans.

Weed Science Laboratory, Beltsville, MD
Thomas E. Devine, (301) 504-6375, tdevine@asrr.arsusda.gov