(Press-News.org) WEST LAFAYETTE, Ind. - Scientists searching for clues to understand how superweeds obtain resistance to the popular herbicide glyphosate may have been missing a critical piece of information, a Purdue University study shows.
Glyphosate, the active ingredient in the weed killer sold under the name RoundUp, is the most widely used herbicide in the United States, but some plants have grown resistant to it. This has caused farmers to turn to additional herbicides. While the mechanisms that have led to resistance are not fully known, Bill Johnson, a professor of weed science; Steve Hallett, an associate professor of weed science; and Jessica Schafer, a graduate student in botany and plant pathology, believe that soil microbes may play a role.
Most laboratory tests done to understand glyphosate resistance are done in sterile soil, void of those microbes. Schafer said Purdue's findings, published online early in the journal Weed Science, show that those microbes may play a significant role in how glyphosate affects plants.
"The soil you're growing the plants in is important to the results," Schafer said. "If we're growing in a sterile media, we could get some false positive results because the plants are more tolerant to glyphosate in those conditions."
Hallett and Schafer grew giant ragweed, horseweed and common lambsquarter in both sterile soil and field soil and subjected them to glyphosate. In each soil, strains of weeds both susceptible and resistant to glyphosate were tested.
Both versions of giant ragweed were damaged more from the glyphosate in field soil. The susceptible version of common lambsquarter was also more heavily damaged in field soil. Horseweed fared the same no matter which soil or strain - susceptible or resistant.
The results show that microbes can play an important role in the activity of glyphosate, presumably by invading the glyphosate-weakened plants. The results also suggest that glyphosate-resistant weeds may be more resistant to disease pressure as well.
"Soil microbes can be minor to major contributors to how glyphosate is able to affect plants," Hallett said. "We may be selecting not only for glyphosate resistance, but inadvertently selecting for weeds that have disease resistance as well."
A weed's ability to withstand glyphosate was based on dry shoot and root weight after testing. The sterile soil used in the study came from field soil exposed to gamma radiation to kill microbes and bacteria. The irradiated soil was tested to ensure that its nutrients were not diminished.
Hallett, Johnson and Schafer said further studies would look at how fungi in the soil affect root development, both with and without glyphosate.
"Dirt is a living organism," Johnson said. "It's important to know how all the pieces interact."
INFORMATION:
The research was conducted with internal funding from Purdue's Department of Botany and Plant Pathology.
Writer: Brian Wallheimer, 765-496-2050, bwallhei@purdue.edu
Sources: Steve Hallett, 765 494-7649, halletts@purdue.edu
Bill Johnson, 765-494-4656, wgj@purdue.edu
Jessica Schafer, 765-496-6690 , schafer3@purdue.edu
PHOTO CAPTION:
Purdue scientists found that soil microbes may play a role in how those weeds react to the popular herbicide glyphosate. Here, glyphosate-susceptible biotypes of giant ragweed react differently to the herbicide. The plant on the left is in sterilized field soil void of microbes, while the plant on the right is in unsterilized soil. (Photo provided by Jessica Schafer)
A publication-quality photo is available at http://news.uns.purdue.edu/images/2012/johnson-glyphosate.jpg
Abstract on the research in this release is available at: http://www.purdue.edu/newsroom/research/2012/120717JohnsonSuper.html
Glyphosate-resistant 'superweeds' may be less susceptible to diseases
2012-07-18
ELSE PRESS RELEASES FROM THIS DATE:
'Sifting' liquid at the molecular level
2012-07-18
Drexel University engineers continue to drive research into the use of carbon nanotubes, straw-like structures that are more than 1,000 times thinner than a single human hair. Their most recent development uses the tiny tubes to separate liquids within a solution.
The researchers have shown that individual carbon nanotubes can act as a separation channel that would force two differing molecules to separate as easily as oil and water. For example, the molecules that comprise two chemically distinct liquids will interact differently with the walls of the nanotube as the ...
Autonomous robot maps ship hulls for mines
2012-07-18
CAMBRIDGE, Mass. — For years, the U.S. Navy has employed human divers, equipped with sonar cameras, to search for underwater mines attached to ship hulls. The Navy has also trained dolphins and sea lions to search for bombs on and around vessels. While animals can cover a large area in a short amount of time, they are costly to train and care for, and don't always perform as expected.
In the last few years, Navy scientists, along with research institutions around the world, have been engineering resilient robots for minesweeping and other risky underwater missions. The ...
Nanoscale scaffolds and stem cells show promise in cartilage repair
2012-07-18
Johns Hopkins tissue engineers have used tiny, artificial fiber scaffolds thousands of times smaller than a human hair to help coax stem cells into developing into cartilage, the shock-absorbing lining of elbows and knees that often wears thin from injury or age. Reporting online June 4 in the Proceedings of the National Academy of Sciences, investigators produce an important component of cartilage in both laboratory and animal models. While the findings are still years away from use in people, the researchers say the results hold promise for devising new techniques to ...
Revised geographic adjustments could improve accuracy of Medicare payments, will not solve access, quality problems
2012-07-18
WASHINGTON — Changing the way that Medicare payments are adjusted to account for regional variations in the cost of providing care as recommended by a previous report from the Institute of Medicine would result in payment increases for some hospitals and practitioners and decreases for others, concludes the Phase II report from the IOM study. Geographic adjustments should be used to ensure the accuracy of payments, said the committee that wrote the report, but they are not optimal tools to tackle larger national policy goals such as improving access to care in medically ...
Report focuses on sustainability of infectious disease surveillance
2012-07-18
ERIE, Pa. - Just as the globalization of trade and travel is rapidly evolving, so is the globalization of infectious diseases and the need for cooperative approaches to detect, prevent and control them, according to Dr. David Dausey, chair of the Mercyhurst University Public Health Department.
The outbreaks of Severe Acute Respiratory Syndrome (SARS) and avian influenza H5N1 in recent years showed how infectious diseases can significantly impact national economies and exposed the need for cooperation in detecting and controlling disease to protect populations and economies.
Such ...
Drug shown to improve memory in those with Down syndrome
2012-07-18
AURORA, Colo. (July 17, 2012) –Researchers at the University of Colorado School of Medicine have found a drug that boosts memory function in those with Down syndrome, a major milestone in the treatment of this genetic disorder that could significantly improve quality of life.
"Before now there had never been any positive results in attempts to improve cognitive abilities in persons with Down syndrome through medication," said Alberto Costa, MD, Ph.D., who led the four- year study at the CU School of Medicine. "This is the first time we have been able to move the needle ...
Caltech researchers find evidence of link between immune irregularities and autism
2012-07-18
PASADENA, Calif.—Scientists at the California Institute of Technology (Caltech) pioneered the study of the link between irregularities in the immune system and neurodevelopmental disorders such as autism a decade ago. Since then, studies of postmortem brains and of individuals with autism, as well as epidemiological studies, have supported the correlation between alterations in the immune system and autism spectrum disorder.
What has remained unanswered, however, is whether the immune changes play a causative role in the development of the disease or are merely a side ...
Obesity plus low vitamin D may add up to a greater risk of diabetes
2012-07-18
PHILADELPHIA (July 17, 2012)— The combination of obesity and vitamin D deficiency may put people at even greater risk of insulin resistance than either factor alone, according to new research from the Drexel University School of Public Health recently published early online in the journal Diabetes Care. Insulin resistance is a major risk factor for Type 2 diabetes, a condition that affects 25.6 million adults and is the seventh leading cause of death in the United States.
"Vitamin D insufficiency and obesity are individual risk factors for insulin resistance and diabetes," ...
A 'Kit' for increasing insulin production
2012-07-18
Scientists from Western University in London, Canada and the Children's Health Research Institute, an Institute within the Lawson Health Research Institute, have identified the critical role of a receptor called c-Kit in the development and function of insulin-producing beta cells, making it an exciting therapeutic target for the management of diabetes. The research, led by Rennian Wang, demonstrated that overexpression of c-Kit not only leads to increased insulin production but also counteracts the early diabetic effects of a high-fat diet. The paper and an accompanying ...
Exposure to sexual content in popular movies predicts sexual behavior in adolescence
2012-07-18
Intuitively it simply makes sense: exposure to sexual content in movies at an early age probably influences adolescents' sexual behavior. And yet, even though a great deal of research has shown that adolescents who watch more risky behaviors in popular movies, like drinking or smoking, are more likely to drink and smoke themselves, surprisingly little research has examined whether movies influence adolescents' sexual behaviors.
Until now.
Over six years, psychological scientists examined whether or not seeing sex on the big screen translates into sex in the real world ...