Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Plants give pests sock in the gut

31.03.2006
A novel enzyme in corn helps the plants defend themselves from voracious caterpillars by disrupting the insects’ ability to digest food, and ultimately killing them, according to researchers. The enzyme could be used in tandem with other biological pesticides such as the Bt toxin to prevent the pests from developing resistance and making the toxin more effective.

"The enzyme is found in insect-resistant strains of corn, and it breaks down proteins and peptides in the insects’ gut. It is a unique active defense against herbivory," says Dawn Luthe, professor of plant stress biology at Penn State.

Luthe and researchers at Mississippi State University have since developed several lines of corn resistant to multiple pests, using conventional plant breeding and insect-resistant strains of corn from Antigua.

Researchers have found that when caterpillars fed on the insect-resistant plants, one enzyme -- Mir1-CP or maize insect resistance cysteine protease, in particular --accumulated at the feeding site within an hour of the caterpillar’s feeding and continued to accumulate at the site for several days.

"Upon isolation and purification of the enzyme, we found that Mir1-CP binds to chitin, a major component of insects and fungi," says Luthe. "Physiological tests show that caterpillars have impaired nutrient utilization when they eat the enzyme. They just can’t convert what they eat into body mass."

Luthe presented the findings at the annual meeting of the American Chemical Society today (March 30) in Atlanta.

With the help of antibodies specific to the enzyme, the researchers were able to determine that Mir1-CP is made in the vascular bundles, or strands of conducting vessels in the stem and leaves of a plant. Luthe thinks that when an insect starts feeding, the enzyme is probably transported to vascular tissue that conducts sugars and other metabolic products upward from the leaves, as well as to the soft tissue found in leaves and stem.

Though it is still unclear whether the transport of Mir1-CP is a specific response to the insect feeding, studies show that maize tissue that naturally expresses Mir1-CP causes a 50 percent inhibition in caterpillar growth. Transgenic black Mexican sweet corn cells that express Mir1-CP inhibit caterpillar growth by 70 percent, Luthe says.

Mir1-CP is harmful to caterpillars mainly because of its damaging effect on their peritrophic matrix. This is a membrane that lines the gut of most insects and aids digestion. It also protects the insects from being invaded by microorganisms and parasites through the food they eat.

At the heart of the matrix is a protein called the insect intestinal mucin, or IIM. It is very similar to the mucus layer in animals and is vital for nutrient utilization because it helps the flow of nutrients into the food gut.

The researchers tested the permeability of the matrix using blue dextran, a fermented sugar solution commonly used as a molecular size marker. Results showed that Mir1-CP created holes in the matrix.

To replicate the test in vivo, the researchers fed caterpillars with plants susceptible to the insects and those resistant to them. Results indicate that after seven days, the level of both IIM and IIM messenger RNA in insects that were feeding on the resistant plants had fallen significantly.

"If the IIM is being degraded by the enzyme, pieces of it should not appear in the fecal pellets of the insect," notes the Penn State researcher.

When used in conjunction with the Bt-toxin, a low dose of Mir1-CP was able to achieve a very high mortality rate in the insects, as well as an extremely low growth rate.

"In the long run, the enzyme degrades the insect’s peritrophic matrix and retards the caterpillar’s ability to generate a new one," says Luthe.

The research has potential global implications in generating a cheap and highly effective way of controlling crop pests.

Other authors of the paper include Tibor Pechan, Srinidi Mohan, Renuka Shivaji, Lorena Lopez, Alberto Camas, Erin Bassford, Seval Ozkan, Peter Ma, all at Mississippi State University; and W. Paul Williams, U.S.D.A.

Amitabh Avasthi | EurekAlert!
Further information:
http://www.psu.edu

More articles from Life Sciences:

nachricht Research team of the HAW Hamburg reanimated ancestral microbe from the depth of the earth
01.03.2017 | Hochschule für Angewandte Wissenschaften Hamburg

nachricht Researchers Imitate Molecular Crowding in Cells
01.03.2017 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

Im Focus: Safe glide at total engine failure with ELA-inside

On January 15, 2009, Chesley B. Sullenberger was celebrated world-wide: after the two engines had failed due to bird strike, he and his flight crew succeeded after a glide flight with an Airbus A320 in ditching on the Hudson River. All 155 people on board were saved.

On January 15, 2009, Chesley B. Sullenberger was celebrated world-wide: after the two engines had failed due to bird strike, he and his flight crew succeeded...

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

A better way to measure the stiffness of cancer cells

01.03.2017 | Health and Medicine

Exploring the mysteries of supercooled water

01.03.2017 | Physics and Astronomy

Research team of the HAW Hamburg reanimated ancestral microbe from the depth of the earth

01.03.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>