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 The balancing act: An enzyme that links endocytosis to membrane recycling
07.12.2016 | National Centre for Biological Sciences

nachricht Transforming plant cells from generalists to specialists
07.12.2016 | Duke University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

NTU scientists build new ultrasound device using 3-D printing technology

07.12.2016 | Health and Medicine

The balancing act: An enzyme that links endocytosis to membrane recycling

07.12.2016 | Life Sciences

How to turn white fat brown

07.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>