Higher levels of atmospheric carbon dioxide facilitate the flow of genes from wild or weedy rice plants to domesticated rice varieties, which could interfere with future rice production, according to new ARS research. Click the image for more information about it.

USDA scientists study effects of rising carbon dioxide on rangelands   Elevated carbon dioxide spurs shrub growth   Elevated carbon dioxide has uneven influence on longleaf communities

USDA Links Gene Flow Between Weedy and Domesticated Rice to Rising Carbon Dioxide Levels

By Ann Perry
May 23, 2012

Beltsville, Md.—New research at the U.S. Department of Agriculture (USDA) confirms that rising levels of atmospheric carbon dioxide facilitate the flow of genes from wild or weedy rice plants to domesticated rice varieties. As a result, domesticated plants could take on undesirable weedy characteristics that may interfere with future rice production.

This is the first study to demonstrate that the effects of increasing atmospheric carbon dioxide concentrations include not only an influence on gene flow between closely related domesticated and wild plant genotypes, but that this gene flow is not the same in both directions. The investigation was conducted by researchers at the Agricultural Research Service (ARS), which is USDA's chief intramural scientific research agency.

"We know that global climate change will require some farmers to revise production strategies in response to shifting weather patterns and crop demands," said ARS Administrator Edward B. Knipling. "These new findings will help plant breeders design and interpret studies on how changes in climate may affect crop response."

ARS plant physiologist Lew Ziska led the investigation. Collaborators included David Gealy, Martha Tomecek, Aaron Jackson, and Howard Black. Ziska and Tomecek work at the ARS Crop Systems and Global Change Laboratory in Beltsville, Md., and the other scientists work at the ARS Dale Bumpers National Rice Research Center in Stuttgart, Ark.

Weedy wild rice, often called red rice, is the same species as domesticated rice and is very difficult to control in production settings. The team conducted a two-year combination growth chamber and field study to document how atmospheric carbon dioxide concentrations affect growth in weedy and domesticated rice and to observe the exchange of genetic material between the two plant types.

Twenty-four-hour carbon dioxide concentrations in the chambers were set at 300, 400 and 600 parts per million (ppm). These concentrations approximated the atmospheric carbon dioxide values present during the end of the 19th century, the current value, and values projected for the end of the 21st century, respectively.

When grown in carbon dioxide concentrations of 400 ppm and 600 ppm, both types of rice put out more tillers and flowers and grew taller, compared to plants grown at carbon dioxide concentrations of 300 ppm. However, these changes in height, which scientists believe are an important factor in pollen sharing and therefore impact gene flow, were more pronounced in the wild rice.

The number of flowers produced by the wild rice grown in 600 ppm carbon dioxide was doubled compared to rice grown at 300 ppm, a significantly larger increase than the flowering increase in the domesticated rice. At the greatest concentration of carbon dioxide, wild rice also produced flowers an average of eight days earlier, a shift that apparently enhanced the likelihood of pollen transfer between the two rice types.

The researchers then conducted a genetic analysis of the hybrid seed offspring of the two rice varieties. The results of these tests indicated domesticated rice transferred only a small amount of genetic material to its weedy relative, even at the greatest concentration of carbon dioxide. But the weedy plants transferred a relatively greater amount of genetic material to their domesticated relatives, which differed from 0.22 percent at carbon dioxide concentrations of 300 ppm to 0.71 percent at carbon dioxide concentrations of 600 ppm.

The transfer of wild genetic material to the domesticated rice line resulted in the production of seed with significant weedy characteristics that would be undesirable in domesticated rice production.

Results from this study were published today in PloS One.

As USDA's chief scientific research agency, ARS is leading America towards a better future through agricultural research and information. ARS conducts research to develop and transfer solutions to help answer agricultural questions that impact Americans every day. ARS work helps to:

• ensure high-quality, safe food and other agricultural products;
   
• assess the nutritional needs of Americans;


• sustain a competitive agricultural economy;
   
• enhance the natural resource base and the environment, and
   
• provide economic opportunities for rural citizens, communities and society as a whole.

Read the magazine story to find out more.

ARS scientists have developed new guidelines for irrigation that could raise net income for southern Idaho sugar beet growers by nearly $6.2 million every year. Click the image for more information about it.

New irrigation guidelines take into account sprinkler droplets' impact on soil crust strength and other factors, increasing protection for soil quality. Click the image for more information about it.

Sugar beets benefit from scientific support   Using less water to grow more potatoes   Calibrating corn production in potato country

USDA Irrigation Research: Good to the Last Drop

By Ann Perry
May 22, 2012

U.S. Department of Agriculture (USDA) scientists are ensuring that farmers in the Pacific Northwest are benefiting from every drop of crop irrigation water.

Agricultural Research Service (ARS) soil scientist Gary Lehrsch has developed irrigation guidelines to protect soil structure, maintain soil quality, sustain soil resources, and improve the delivery of water distributed via sprinkler irrigation to the root zones of growing crops.

ARS is USDA's chief intramural scientific research agency, and this work supports the USDA priorities of responding to climate change and promoting international food security.

Lehrsch works at the ARS Northwest Irrigation and Soils Research Laboratory in Kimberly, Idaho. In one 5-year investigation, he and colleagues evaluated the effect of sprinkler droplet kinetic energy on soil crust strength and aggregate stability. They irrigated sugar beet plots using sprinkler systems equipped with spray heads mounted six feet above the soil.

The spray heads were modified to produce water droplets having either low- or high-droplet energies. The team measured aggregate stability and surface soil penetration resistance-a measure of crust strength-about four days after the first postplant irrigation and 14 days after the last irrigation.

Lehrsch and his colleagues found that the portion of stable soil aggregates decreased from 66 percent to 55 percent when the irrigation's energy increased from 0 percent (in test plots protected by nylon netting) to the lowest rate under investigation. Even more importantly, they found that sugarbeet seedling emergence increased 6.4 percent when droplet energy was reduced 50 percent, an emergence increase that could raise net income for southern Idaho sugar beet growers by nearly $6.2 million every year.

The scientists concluded that these restrictions should be in place until sugarbeet seedlings have emerged and become established. Then the sprinklers can be reconfigured to apply greater water volumes, at necessarily greater levels of energy, for the rest of the growing season.

Read more about this research in the May/June 2012 issue of Agricultural Research magazine.

Read the magazine story to find out more.

ARS researchers have discovered a new virus called "phiCA82" in turkeys that potentially could be used as an alternative to antibiotics to fight multi-drug-resistant pathogens in poultry. Click the image for more information about it.

New vaccine developed for Newcastle disease   USDA scientists, cooperators create the first genomic map of the domesticated turkey   Avian influenza genome sequences released

New Technique Used to Discover New Viruses in Poultry

By Sandra Avant
May 17, 2012

In a search to find better ways to control viral enteric diseases in birds, U.S. Department of Agriculture (USDA) scientists have unearthed a treasure trove of previously known and unknown viruses in poultry by using a powerful new molecular tool called metagenomics.

Each year, disorders like poult enteritis mortality syndrome, poult enteritis complex, and runting-stunting syndrome cause diarrhea in turkeys and chickens, resulting in decreased weight, mortality and increased production costs. Several viruses have been associated with enteric or intestinal diseases, but no single causative agent has been found.

Unlike traditional sequencing that characterizes genes in a single organism, metagenomics detects the nucleic acid of thousands of organisms in an entire community. Using this technique, Laszlo Zsak, researcher leader of the Endemic Poultry Viral Diseases Research Unit at the Agricultural Research Service (ARS) Southeast Poultry Research Laboratory in Athens, Ga., discovered a new virus that might have future antimicrobial applications.

ARS is the chief intramural scientific research agency of USDA.

Zsak and ARS microbiologist Michael Day, also at Athens, found a short DNA sequence of the newly discovered virus and designed a technique to sequence its entire genome. The virus, called "phiCA82," is the type of virus that naturally kills bacteria and belongs to a group known as "microphages" or phages, which can potentially be used as alternatives to antibiotics and as tools to fight multi-drug-resistant pathogens.

In the study, the scientists extracted and analyzed nucleic acid from poultry intestine samples gathered from U.S. commercial poultry flocks infected with enteric diseases. In addition to the novel phage, common avian viruses like astrovirus, reovirus and rotavirus, and RNA viruses belonging to the Picornaviridae family were detected. However, the scientists were surprised to discover previously unknown turkey viruses like picobirnavirus, a virus implicated in enteric disease in other agricultural animals, and a calicivirus, a type of virus often associated with human enteric diseases.

In earlier studies, Zsak and Day used metagenomics to identify and analyze for the first time the complete genome of a novel chicken parvovirus. They also developed a PCR-polymerase chain reaction-assay that is highly sensitive and specific in detecting viruses in birds.

Read more about this research in the April 2012 issue of Agricultural Research magazine.

Read the magazine story to find out more.

ARS scientists are looking for a way to inhibit microbial growth in cotton socks, T-shirts and other clothes using silver particles ranging from 2 to 6 nanometers in size. Click the image for more information about it.

Nanotech cotton opens up new possibilities for the fiber-and its fans   Cotton's potential for padding nonwovens   Cotton: a body armor for wounds?

New Treatments Could Reduce Odors in Cotton Fabric

By Jan Suszkiw
May 10, 2012

Socks, T-shirts and other garments could become less hospitable to odor-causing bacteria, thanks to new antimicrobial treatments being investigated by U.S. Department of Agriculture (USDA) scientists in New Orleans, La.

In studies at the Southern Regional Research Center operated there by USDA's Agricultural Research Service (ARS), a team of scientists is seeking to inhibit microbial growth in cotton using silver particles ranging from 2 to 6 nanometers in size. ARS is USDA's chief intramural scientific research agency.

Silver nanoparticles have been used previously as antimicrobial agents in products, including clothes, plastic food containers and medical textiles. However, the synthetic methods of producing them have relied on the use of toxic agents and organic solvents, according to ARS team leader Brian Condon.

As an environmentally friendly alternative, his team showed that polyethylene glycol and water worked just as well in generating the silver particles. Moreover, the particles were of the desired size, reported Condon, ARS engineer Sunghyun Nam, and former ARS researcher Dharnidhar Parikh, in a recent issue of the Journal of Nanoparticle Research.

The researchers also devised a method of prompting silver nanoparticles to form directly on cotton fibers, eliminating the handling and storage of the antimicrobial agents prior to application. This should give cotton an advantage over synthetic fabrics, which have not been amendable to silver nanoparticle treatment, notes Condon, who leads the ARS center's Cotton Chemistry and Utilization Research Unit.

In another approach, ARS chemist Vince Edwards, together with Condon, developed a treatment for impregnating nonwoven cotton fabrics with lysozyme, an enzyme that slices open the cell walls of microorganisms, killing them—including those that cause odor or infection. Similar enzymes also have potential use in biodefense applications, such as deactivating nerve agents, adds Condon.

The researchers are seeking commercial partners to help usher the advances into the marketplace, all with an eye towards assuring the viability of American cotton at a time of increasing production costs, dwindling resources and global competition.

Read more about this research in the April 2012 issue of Agricultural Research magazine.

Read the magazine story to find out more.

ARS scientists have developed a system using DNA "barcodes" to identify emerging biotypes of Russian wheat aphids, an insect pest that does more than $200 million in damage annually to wheat and other cereal crops in the United States. Click the image for more information about it.

No mistaking this bug with new insect ID technique   ARS preserves plants and animals for future needs   New barley is bad news for Russian wheat aphids

New Tool for Tracking a Voracious Pest

By Dennis O'Brien
May 8, 2012

Since it first appeared in Texas in 1986, the Russian wheat aphid has cost U.S. wheat growers an estimated $200 million each year. But U.S. Department of Agriculture (USDA) scientists have developed a new tool to keep track of this nasty worldwide threat to wheat and barley and to provide guidance to researchers and plant breeders on control strategies.

Gary Puterka, who is with the Agricultural Research Service (ARS) Wheat, Peanut and Other Field Crops Research Unit in Stillwater, Okla., and his colleagues have developed a system that uses DNA "barcodes" to identify emerging biotypes of Russian wheat aphids that threaten wheat and other cereal crops. In DNA barcoding, scientists sequence a designated part of an organism's genome and produce a barcode from it for a systematic comparison with the sequenced DNA of other closely related species.

ARS is USDA's chief intramural scientific research agency, and this research supports the USDA goal of promoting agricultural sustainability.

Russian wheat aphids have been controlled by resistant wheat varieties, but the appearance of a new biotype that overcame resistance in 2003 has forced growers to rely on insecticides while breeders develop new, resistant varieties. Monitoring of Russian wheat aphid populations for the emergence of new biotypes is important because researchers and breeders need to know resistant crops being developed will be effective against emerging biotypes.

Aphid species typically produce eggs in the fall and place them in wheat and wild grass leaves. The eggs of various aphid species are often placed together and that makes locating new biotypes difficult. Puterka and Kevin Shufran, a former ARS scientist who recently retired from the Stillwater unit, have developed a way to tell them apart.

The researchers extracted DNA from the eggs of 10 previously identified species of aphids, including several of the Russian wheat aphid's closest relatives, and sequenced a variable part of the CO1 mitochondrial gene. In a blind experiment, Shufran compared DNA from eggs of species provided by Puterka, who masked their identities. Through genetic analyses, Shufran was able to DNA barcode the different aphid species. This will greatly improve their effort in locating new biotypes. Results were published in Annals of the Entomological Society of America.

Read more about this research in the April 2012 issue of Agricultural Research magazine.

Read the magazine story to find out more.

ARS is studying a potential biological control for the kudzu bug, which does feed on the kudzu vine, but also could be a major pest of soybeans, peanuts and other legumes. Click the image for more information about it.

Overseas lab seeks U.S. weed control "recruits"   Trap would help keep stink bugs outdoors

Biocontrol Agent Tested to Battle Invasive Kudzu Bug

By Jan Suszkiw
May 3, 2012

Don't let its common name fool you: The "kudzu bug" isn't to be trusted.

Sure, it will feed voraciously on the stems of kudzu, the "Vine That Ate the South." But Megacopta cribraria also has a taste for legumes, including soybeans. And in Georgia, where this native of Asia was first discovered in October 2009, there's worry the pest will infest peanuts, endangering the state's $2-billion legume crop.

U.S. Department of Agriculture (USDA) scientists and their collaborators haven't been idle, however. At the Agricultural Research Service (ARS) Stoneville Research Quarantine Facility in Stoneville, Miss., entomologist Walker Jones is evaluating a top natural enemy of the bug, the parasitic wasp Paratelenomus saccharalis. ARS is USDA's principal intramural scientific research agency.

The wasp is nonstinging and harmless to humans, pets and other animals. However, it lays its eggs in those of Megacopta's. Upon hatching, the wasp's maggot-like brood devour the pest's own developing embryos, reducing the size of the next generation.

Megacopta belongs to a unique insect family that doesn't occur anywhere in the Americas. Thus, importing its co-evolved natural enemies isn't expected to endanger native U.S. bug species, explains Walker, who leads the ARS Biological Control of Pests Research Unit in Stoneville. First, however, the wasp must pass muster on a long list of requirements to confirm its host specificity and environmental safety, starting with the quarantine trials.

Toward that end, Walker is screening eggs of native species of related bugs to learn whether the wasp will attack them, and so far it hasn't. The evaluations require a steady supply of bugs representing four families and 15 species sent to Walker by collaborators across the country.

Besides Georgia, Megacopta has also been reported in parts of Alabama, Tennessee, North Carolina, South Carolina and Virginia. A university-led effort is tracking the pest's spread and studying its basic biology, host crop range, economic impact, chemical control and vulnerability to native predators, parasites and pathogens.

Read more about this research in the May/June 2012 issue of Agricultural Research magazine.

Read the magazine story to find out more.

ARS entomologist Matt Greenstone is using the Colorado potato beetle's barcoded DNA to determine how effective different predator insects are at controlling it. Click the image for more information about it.

No mistaking this bug with new insect ID technique   Threat to grapevines and gardens now easier to pinpoint   Bacterium curbs several insect pests

Barcoding Insects as a Way to Track and Control Them

By Dennis O'Brien
April 30, 2012

Barcodes may bring to mind the sales tags and scanners found in supermarkets and other stores. But U.S. Department of Agriculture (USDA) scientists are using "DNA barcodes" to monitor insects that damage crops as diverse as wheat, barley and potatoes, and to make pest management decisions.

In DNA barcoding, scientists sequence a designated part of an organism's genome and produce a barcode from it for a systematic comparison with the sequenced DNA of other closely related species. DNA barcodes are being developed on a wide range of plants and animals as part of a global effort to catalogue the diversity of life on Earth.

Matthew Greenstone, an Agricultural Research Service (ARS) entomologist at the agency's Invasive Insect Biocontrol and Behavior Laboratory in Beltsville, Md., is using DNA barcodes in an unconventional way: to identify insect predators best equipped to control the Colorado potato beetle, which is the single most damaging insect pest of potatoes in the Eastern United States.

ARS is USDA's chief intramural scientific research agency, and this research supports the USDA goal of promoting agricultural sustainability.

Numerous studies have analyzed the gut contents of predatory insects to evaluate their ability to control pests in a field. But predators digest prey at different rates, so simple gut analysis is insufficient for accurately comparing the effectiveness of different predators. Greenstone has fine-tuned the approach, using barcodes to come up with a way to factor in how quickly different insects digest prey.

He and his colleagues collected four potato beetle predators, fed them lab-raised potato beetles and determined how long the pest's barcoded DNA could be detected in the predators' guts. The results, published in the journal Entomologia Experimentalis et Applicata, show the importance of taking digestive rates into account when evaluating insect predators as biocontrol agents. They also may provide guidance to growers on the most effective control strategies for combating a voracious pest.

Read more about this research in the April 2012 issue of Agricultural Research magazine.

Read the magazine story to find out more.

ARS researchers are looking at phytochemical differences between green tea, brewed from leaves, and green tea dietary supplements. Photo courtesy of Microsoft clip art.

Better analysis methods for vitamin D   Data on food antioxidants aid research   A food's composition, by any preparation method, is not the same

Analyzing Green Tea Leaves and Supplements

By Rosalie Marion Bliss
April 27, 2012

Quality control is a key factor in making sure green tea dietary supplement products pack the same antioxidant punch as green tea leaves used for brewing beverages, according to U.S. Department of Agriculture (USDA) scientists.

Green tea-based dietary supplements have gained popularity in the U.S. market in recent years. But when it comes to sipping green tea versus taking the dietary supplement form, the better choice relative to health is unknown.

Scientists with USDA's Agricultural Research Service (ARS) in Beltsville, Md., studied the differences between phytochemicals in green tea dietary supplements and green tea leaves used for brewing beverages. ARS is USDA's principal intramural scientific research agency.

Chemist Pei Chen, with the ARS Beltsville Human Nutrition Research Center, headed the study. Chen and colleagues Jianghao Sun and Long-Ze Lin analyzed extractions of 20 commercially available green tea dietary supplement products and eight dry green tea leaf samples. They compared the chemical constituents of the samples using an analytical technique called "HPLC/MS." This technique can separate one chemical constituent from another in a complex matrix. The technique also has the ability to identify and quantify chemical constituents accurately.

The study demonstrated that phytonutrients called flavonol glycosides were degraded and that another phytonutrient called catechin had oxidized during manufacturing and storage for many of the green tea supplement samples studied. They also found some additives in the supplements that were not listed on the labels.

The researchers concluded that although there are fine green tea dietary supplement products, there is no way for the consumer to know the qualities of those products from reading the labels. In addition, the consumer may ingest other botanical extracts unintentionally, and the quality of those green tea products varies significantly. The 2011 study was published in the Journal of AOAC International.

Read more about this research in the April 2012 issue of Agricultural Research magazine.