The gene's role in creating resistance to Hessian flies was a surprise to U.S. Department of Agriculture and Purdue University researchers, discoverers of the gene and its function. They made the finding as they investigated new, long-term methods to protect wheat from insect damage.
"This is a different kind of defense than we were expecting," said Christie Williams, a USDA-Agricultural Research Service scientist and Purdue Department of Entomology adjunct assistant professor. "Usually we expect the plant to fortify its cell walls or make poisons to use against insects and pathogens."Instead, the researchers found that a specific protein, called HFR-3, one of a group of substances called lectins, is capable of binding with a carbohydrate complex in the Hessian fly larvae. The lectin acts as a key to the carbohydrate structure, known as a chitin.
Some Hessian fly larvae, which are called virulent, are capable of ridding their bodies of lectin and surviving. Avirulent larvae are unable to deactivate the lectin.
However, the researchers believe that plants resistant to Hessian fly invasions may make several strains of lectins in response to virulent larvae, Williams said.
Results of the study are published in the January issue of the journal Molecular Plant Pathology.
Researchers also discovered that not only do lectins damage the insect's mid-stomach, the lectins also taste bad and have some toxicity.
"By studying these different wheat genes, we're starting to put together a bigger picture of how Hessian fly–wheat interactions trigger resistance in the plant," Williams said. "We think that some of this has to do with the plant producing enough lectin that it just becomes so unpalatable that the insects can't feed and they starve to death."
Wheat plants that produce few or no lectins that bind to chitin are susceptible to Hessian fly larvae attack, she said. In addition, some virulent larvae can reprogram plant development so that cells in leaves and the base of the plant where the insects feed pump out nutrients favored by the insect. If this happens then even the weak, avirulent larvae on the same leaf have a chance to survive.
The researchers discovered that Hessian fly larvae reprogramming of resistant plant cells only occurs at sites where the insects attack. The study also revealed that increased numbers of larvae on a plant caused a parallel increase in lectin. This shows that wheat plant responses to these insects are localized and take less energy than a more global resistance response.
"Figuring out some of the ways that a plant is able to respond to insects with resistance will be useful in crop breeding programs," Williams said. "We're finding compounds like this chitin-binding lectin that don't cost the plant much to produce, unlike producing poisons and stronger walls. Those inducible defenses use a lot of a plant's energy that could be used toward growth and reproduction."
The scientists currently are looking for regulatory regions in Hessian fly-susceptible wheat genes that might act as vehicles to carry lectin or a toxin into plants to halt the virulent insects, Williams said. The regulatory regions, or promoters, would be from genes that the fly larvae ordinarily manipulate so plants will produce useful nutrients for the insect. Instead, the promoter would be hooked up to a lectin or toxin gene and inserted into the cells. When larvae manipulate the promoter, they would receive gut-altering lectin instead of nutrients.
To advance their investigation into developing more resistant plants, the researchers are beginning work on a single microchip that would be an array of genes from both the Hessian fly and wheat. This will allow the scientists to study insect-plant interactions. Knowing the timing and location of those interactions would enable the scientists to use the promoter tactic only in the vegetative parts of the wheat plant rather than in the head or grain portions. This will protect the grain quality and the consumer.
"Once we understand which genes are active and the timing of the interactions, we can really understand what the insect says to the plant and how the plant responds," Williams said.
The Hessian fly, which German mercenaries apparently introduced into North America during the Revolutionary War, causes catastrophic losses if not controlled by resistant plants. During the 1980s the state of Georgia suffered $28 million in lost wheat in one year after the fly overcame the plants' resistance gene used in the area at the time.
The Hessian fly is particularly insidious because it actually can control the wheat plant's development.
The adult fly lays eggs on the plant leaves. After the eggs hatch, the resulting tiny, red larvae crawl down to the base of the wheat where they feed on the plant. If the plant isn't resistant to the insect, the larvae inject chemicals from their saliva into the plant that completely alter the wheat's physiology and growth.
The other researchers on this study were USDA postdoctoral students Kurt Saltzmann and David Puthoff, Purdue graduate students Marcelo Giovanini and Martin Gonzalo, and Purdue professor of agronomy Herbert Ohm.
The USDA Agricultural Research Service Crop Production and Pest Control Research Unit and the Ministry of Education of Brazil CAPES Programme provided support for the study.
Writer: Susan A. Steeves, (765) 496-7481, firstname.lastname@example.org
Source: Christie Williams, (765) 494-6753, email@example.comAg Communications: (765) 494-2722;
Susan A. Steeves | EurekAlert!
Water forms 'spine of hydration' around DNA, group finds
26.05.2017 | Cornell University
How herpesviruses win the footrace against the immune system
26.05.2017 | Helmholtz-Zentrum für Infektionsforschung
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
26.05.2017 | Life Sciences
26.05.2017 | Life Sciences
26.05.2017 | Physics and Astronomy