Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Restoring a natural root signal helps to fight a major corn pest

04.08.2009
Field trials in the US show that enhancing the attractiveness of maize roots to insect-killing nematodes can effectively fend off Western corn rootworm

A longstanding and fruitful collaboration between researchers at the Max Planck Institute for Chemical Ecology and the University of Neuchâtel in Switzerland, together with contributions from colleagues in Munich and the US, has produced another first: the successful manipulation of a crop plant to emit a signal that attracts beneficial organisms.


The Western corn rootworm (insert) is a devastating pest of maize roots. By emitting the volatile compound E-beta-caryophyllene in response to rootworm feeding, maize plants naturally attract insect-killing nematodes. Using genetic transformation, the signal was restored in an American line and in field tests it was shown that this dramatically increased the protection that the plants received from the nematodes. Matthias Held and Sergio Rasmann, University of Neuchâtel, Switzerland

Genetic transformation of maize plants resulted in the release of the naturally active substance (E)-beta-caryophyllene from their roots. The substance attracts nematodes that attack and kill larvae of the Western corn rootworm, a voracious root pest. In field tests, the enhanced nematode attraction resulted in reduced root damage and considerably fewer surviving rootworms.

Further fine-tuning of this natural defense strategy will allow for an environmentally friendly growing of maize with minimized use of synthetic insecticides. The project was carried out within the framework of the Swiss National Centre of Competence in Research (NCCR Plant Survival). (Proc. Natl. Acad. Sci. USA, Early Edition, August 3-7, 2009)

The Western corn rootworm (Diabrotica virgifera virgifera) is the most damaging maize pest in the US and is responsible for enormous financial losses. Current methods to control the rootworm pest include insecticides, crop rotation and transgenic Bt maize lines that are not yet approved in Europe. After first invading the Balkans, the pest has since 2007 also been found in southern Germany. The corn rootworm larvae feed on root hairs and bore themselves into the maize roots.

The results are devastating: The plants take up less water and nutrients, and with the root mass severely reduced the plants lodge and collapse. In areas in Germany where the corn rootworm is a potential threat, the Federal Office of Consumer Protection and Food Safety (BVL) establishes safety zones and enacts the use of the insecticide chlothianidine. In spring 2008 this insecticide was directly applied on the seeds, but during sowing it was unintentionally emitted as dust from abraded seeds, contaminated flowers, and poisoned 330 million honey-bees.

"Instead of using insecticides, the use of natural enemies of the corn rootworm could be much more environmentally friendly," says Jörg Degenhardt, who was recently appointed professor at the University of Halle. While working in the group of Jonathan Gershenzon at the Max Planck Institute for Chemical Ecology in Jena he had already contributed to a key discovery four years ago by Sergio Rasmann in the group of Ted Turlings at the University of Neuchâtel. They found that maize roots attacked by rootworm attract nematodes by releasing (E)-beta-caryophyllene (EßC). One striking finding was that, after decades of breeding, most North American maize varieties no longer emitted EßC and had lost the ability to attract protective nematodes.

Therefore the research group in Jena and Neuchâtel teamed up again in an attempt to restore the EßC signal in a variety that normally does not emit the substance. Jörg Degenhardt, with the help of Monika Frey at the Technical University of Munich, transformed a non-emitting maize line with a gene that encodes an EßC generating enzyme, resulting in continuous emissions of EßC. Next, the Turlings group in Neuchâtel sent Ivan Hiltpold to Missouri, where, under the guidance of Bruce Hibbard of the United States Department of Agriculture, the transformed plants were tested in the field.

"Our study showed that the re-established natural EßC signal greatly enhanced the effectiveness of nematodes in controlling Western corn rootworm", Hiltpold reports. In rows with EßC-producing maize plants root damage was greatly reduced; 60% fewer Diabrotica beetles emerged as compared to rows with non-transformed maize plants. This control efficiency approaches that of conventional synthetic insecticides used to fight Diabrotica. Subsequent laboratory studies confirmed that transgenic plants attracted significantly more nematodes than the non-transformed equivalents.

"The use of this indirect defense is an attractive strategy to increase plant resistance against herbivores and to reduce the use of chemical pesticides," Degenhardt says. "The transgenic corn plants used in these experiments have no commercial value and the experiments simply served a 'proof of principle' that the EßC emission helps to protect the plants against underground infestation." The EßC trait is present in other, mainly European, corn varieties as well as in the maize ancestor species. The trait could be reintroduced into deficient plants by conventional breeding. On the other hand, generating EßC emitting maize varieties by means of gene technology may have advantages: it is faster and prevents the loss of other important traits.

In further experiments the researchers want to determine the most effective way the nematodes and their response to the EßC can be applied. Moreover, the diffusing properties of caryophyllene make it an ideal belowground signal that could also serve to protect other crop plants. A patent for this approach has been filed. [JWK, TT]

Citation:
Jörg Degenhardt, Ivan Hiltpold, Tobias G. Köllner, Monika Frey, Alfons Gierl, Jonathan Gershenzon, Bruce E. Hibbard, Mark R. Ellersieck and Ted C. J. Turlings: Restoring a maize root signal that attracts insect-killing nematodes to control a major pest. Proc. Natl. Acad. Sci. USA, Early Edition, August 3-7, 2009, DOI: 10.1073/pnas.0906365106
Contact:
Prof. Dr. Jörg Degenhardt, Martin-Luther-Universität Halle-Wittenberg, Inst. für Pharmazie, Hoher Weg 8, D-06120 Halle (Germany). Tel.: +49 (0) 345 - 5525100. joerg.degenhardt@pharmazie.uni-halle.de

Prof. Dr. Ted C. J. Turlings, University of Neuchâtel, Institute of Biology, C. P. 158, CH-2009 Neuchâtel (Switzerland). Tel.: +41 (0) 32 718 31 58. ted.turlings@unine.ch

Pictures: Angela Overmeyer M.A., Max-Planck-Institute for Chemical Ecology, Jena (Germany). Tel.: +49 3641 57-2110. overmeyer@ice.mpg.de

Dr. Jan-Wolfhard Kellmann | Max-Planck-Institut
Further information:
http://www.ice.mpg.de

More articles from Agricultural and Forestry Science:

nachricht Climate change, population growth may lead to open ocean aquaculture
05.10.2017 | Oregon State University

nachricht New machine evaluates soybean at harvest for quality
04.10.2017 | University of Illinois College of Agricultural, Consumer and Environmental Sciences

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

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

Im Focus: Salmonella as a tumour medication

HZI researchers developed a bacterial strain that can be used in cancer therapy

Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Microfluidics probe 'cholesterol' of the oil industry

23.10.2017 | Life Sciences

Gamma rays will reach beyond the limits of light

23.10.2017 | Physics and Astronomy

The end of pneumonia? New vaccine offers hope

23.10.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>