Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Toxic Substances in Banana Plants Kill Root Pests

11.12.2013
Banana plants protect themselves from parasitic nematodes by increasing local concentrations of defensive substances in infected root tissues.

Bananas are a major food staple for about 400 million people in the tropical and subtropical regions of Asia, Africa and Latin America. However, banana yields worldwide are severely threatened by pests.


Few red, phenylphenalenone containing regions on the root of the resistant Yangambi km5 root within healthy root tissue (below) and massive root damage in the susceptible Grande Naine banana (above).

D. Hölscher / Max Planck Institute for Chemical Ecology


Microscopic image of the nematode Radopholus similis: Inside the roundworm the lipid droplets that store the toxin, phenylphenalenone anigorufone (yellow), are clearly visible.

S. Dhakshinamoorthy / University of Leuven, Belgium

Dirk Hölscher from the Max Planck Institute for Chemical Ecology in Jena, Germany, and an international team of researchers have discovered that some banana varieties accumulate specific plant toxins in the immediate vicinity of root tissue that has been attacked by the parasitic nematode Radopholus similis.

This local accumulation is crucial for the plant’s resistance to this pest organism. The toxin is stored in lipid droplets in the body of the nematode and the parasite finally dies. These findings provide important clues for the development of pest-resistant banana varieties. (Proceedings of the National Academy of Sciences USA, December 9; 2013, DOI 10.1073/pnas.1314168110)

Banana yields worldwide threatened by pests

Bananas are among the world’s most important food crops. Dessert bananas are produced primarily for homegrown consumption in China and India and for export to the northern hemisphere in Latin America. In Europe, they represent the most popular tropical fruit. Plantains (a type of cooking banana) are important components of daily meals in Africa and Southeast Asia. They are highly prized because of their high contents of nutrients, such as potassium, magnesium and vitamins B and C.

Apart from fungi and insects, the parasitic nematode Radopholus similis is considered a major banana pest. It attacks the roots of banana plants, causing slower growth and development of the plant and fruit. In the final stage of the disease plants topple over − often when already bearing an immature fruit bunch. Yield losses up to 75% can be the result of R. similis infestation. In order to control such pests in banana plantations, high doses of synthetic pesticides are used which not only cause ecological damage, but can also have severe negative effects on the health of people who are exposed to these chemicals.

Scientists at the Max Planck Institute for Chemical Ecology and their colleagues from universities in Leuven (Belgium), Jena, Kassel-Witzenhausen, Halle, Bonn and Bremen, as well as the Leibniz Institute for Natural Product Research and Infection Biology and the Leibniz Institute of Photonic Technology in Jena have now taken a closer look at the plant-nematode interactions in the context of resistance versus susceptibility. They compared two banana varieties, a resistant and a susceptible one, and studied their defense responses to Radopholus similis.

Phenylphenalenones: Local accumulation of defensive substances in infected regions of root tissues inhibits further propagation of the pest

The researchers used modern spectroscopic analysis and imaging techniques and were able to identify and localize defense substances in banana roots: The plants accumulated so-called phenylphenalenones only in infected regions of their roots, but not in healthy tissues. This was the case in both the resistant and the susceptible banana variety. The concentration of the most active compound anigorufone, however, was much higher in the immediate vicinity of lesions on the roots of resistant bananas in comparison to infected root tissues of the nematode susceptible banana plants. “The production of the toxin alone is not responsible for the banana plant’s resistance to nematodes. It is the differential concentration in specific regions of the roots, which is particularly high at the precise location of the nematode attack, which makes the difference and confers resistance. We measured far higher concentrations of the toxin in these localized regions in the resistant banana variety,” Dirk Hölscher summarizes the results.

Lipid droplets containing the active compounds visible in the nematode

The toxic effect of anigorufone and other substances was tested on living nematodes. It turned out that it was in fact anigorufone which was most toxic to the pest organism. By using imaging techniques, the researchers were able to visualize the plant toxin within the body of the roundworm. There the lipid-soluble anigorufone accumulated in lipid droplets which increased in size as they converged and finally killed the nematode. Why these complex lipid droplets are formed and why the nematodes cannot metabolize or excrete the toxin still needs to be clarified. However, it is likely that the growing lipid droplets displace the inner organs of the nematode causing an eventual metabolic dysfunction.

The scientists will now try to find out how resistant banana plants biosynthesize and translocate the defense compounds on a molecular level. Such insights will provide important clues for the development of banana varieties which are resistant to the nematodes. This could help to minimize the excessive use of highly toxic pesticides in banana plantations which jeopardize the environment and people’s lives. [AO]

Original Publication:
Hölscher, D., Dhakshinamoorthy, S., Alexandrov, T., Becker, M., Bretschneider, T., Bürkert, A., Crecelius, A. C., De Waele, D., Elsen, A., Heckel, D. G., Heklau, H., Hertweck, C., Kai, M., Knop, K., Krafft, C., Madulla, R. K., Matthäus, C., Popp, J., Schneider, B., Schubert, U., Sikora, R., Svatoš, A., Swennen, R. (2013). Phenalenone-type phytoalexins mediate resistance of banana plants (Musa spp.) to the burrowing nematode Radopholus similis. Proceedings of the National Academy of Sciences of the United States of America. DOI 10.1073/pnas.1314168110

http://dx.doi.org/10.1073/pnas.1314168110

Further Information:
Dr. Dirk Hölscher, Max Planck Institute for Chemical Ecology,
Tel. +49 3641 57-2551, E-Mail hoelscher@ice.mpg.de
Dr. Bernd Schneider, Max Planck Institute for Chemical Ecology,
Tel. +49 3641 57- 1600, E-Mail schneider@ice.mpg.de
Prof. Dr. Andreas Bürkert, University of Kassel-Witzenhausen,
Tel. +49 5542-98-1228, E-Mail buerkert@uni-kassel.de
Contact and Picture Requests:
Angela Overmeyer M.A., Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07743 Jena, Germany, Tel. +49 3641 57-2110, E-Mail overmeyer@ice.mpg.de

Angela Overmeyer | Max-Planck-Institut
Further information:
http://www.ice.mpg.de/ext/1055.html?&L=0
http://www.ice.mpg.de/ext/735.html

More articles from Agricultural and Forestry Science:

nachricht New gene for atrazine resistance identified in waterhemp
24.02.2017 | University of Illinois College of Agricultural, Consumer and Environmental Sciences

nachricht Researchers discover a new link to fight billion-dollar threat to soybean production
14.02.2017 | University of Missouri-Columbia

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: 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...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

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

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>