Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Herbivore defense in ferns

21.11.2012
Unlike flowering plants, bracken ferns do not release any odor signals to attract the enemies of their attackers for their own benefit.

They dominated the earth for 200 million years and numerous different species can still be found all over the world: mosses, horsetails and ferns.


The larva of the sawfly Strongylogaster multifasciata feeds on a bracken leaf. Like other plants, ferns produce toxic substances and can successfully defend themselves against herbivores. Unlike flowering plants, however, bracken ferns do not emit volatiles that attract parasitoids or predators of herbivorous larvae.

Photo: Max Planck Institute for Chemical Ecology/ Venkatesan Radhika

Researchers from the Max Planck Institute for Chemical Ecology in Jena, Germany, have now found out that bracken ferns (Pteridium aquilinum) do not release any volatiles when they are attacked − unlike many of the now dominant and evolutionary younger flowering plants.

Such an emission of volatile compounds may attract the pest insects’ enemies, such as ichneumon wasps or predatory bugs, that parasitize herbivores. Nevertheless, volatile emission could be also elicited in fern fronds, if they had been treated with plant hormone jasmonic acid. Jasomonic acid induces the synthesis of volatile substances in flowering plants. This suggests that ferns can in principle mobilize this kind of defense reaction. However, they do not use this indirect defense to fend off herbivores.

Only few herbivores attack ferns

Ferns are so-called vascular cryptogams, because they don’t produce flowers and seeds like the currently largest group of plants, the spermatophytes or seed plants. Ferns reproduce and spread entirely via spores. Their metabolic activities and especially their defenses against herbivores, however, are similarly efficient in comparison to flowering plants. Ferns can be found in large populations all over the world, although their evolutionary age is more than 400 million years.

Botanists consider the bracken fern Pteridium aquilinum as one of the most widely distributed plant species. It can be found in the most different habitats. Herbivores attack bracken ferns strikingly less often than flowering plants. One explanation for this phenomenon could be that fern fronds contain especially toxic substances that keep pest insects at bay: Chemical composition analysis detected indanones, cyanogenic glycosides and tannins, amongst other substances. But can those “living fossils” also use indirect defenses against their enemies, like other plants do?

Defense mechanisms in bracken fern include indirect defenses. However, herbivory does not induce them.

Beans, corn, cotton, poplar trees, tobacco plants and potatoes: These and other flowering plants are known to produce the plant hormone jasmonic acid in their leaves after herbivore attack. Jasmonic acid stimulates the synthesis of volatile substances, such as compounds of the terpenoid family. This defense strategy can be used by plants to attract the enemies of herbivorous insect larvae. Venkatesan Radhika, PhD student in the Department of Bioorganic Chemistry of the institute, wanted to find out, whether bracken ferns could also emit these attractants when they were attacked. She used larvae of two insect herbivore species to damage the fern fronds: fern specialist Strongylogaster multifasciata and the generalist herbivore Spodoptera littoralis, which feeds on many different plants. She also used a robotic device, MecWorm, which continuously punched a limited area of the fern frond with a metal bolt, thereby mimicking the mechanical wounding caused by feeding herbivores. The result: The fern fronds release only very small amounts of volatile compounds, if at all. Even the signal molecule jasmonic acid could hardly be detected in the fronds.
However, if fern fronds were directly treated with jasmonic acid, they responded like the leaves of flowering plants and they released a typical odor bouquet. The scientists studied this effect in more detail and discovered that the release of volatile terpenoids from the fern could even be induced by treatment with early precursors of jasmonic acid synthesis (OPDA and linolenic acid). Biochemical experiments revealed that these volatile terpenoids are produced by the same metabolic pathway already known from flowering plants. “It is likely that the herbivory-induced accumulation of jasmonic acid is not sufficient to trigger the production of volatile compounds in our experiments,” says Wilhelm Boland, director of the department.

Could it be possible that ferns do not need indirect defenses by means of volatile emission? Is the presence of highly toxic substances in the fern fronds sufficient to fend off herbivores? “We can only speculate,” says Boland. Indirect defense strategies may have evolved from originally direct defenses (e.g. in the Chinese ladder brake, Pteris vittata) or, on the other hand, in the context of pollinator attraction to volatiles, which is a trait that has naturally evolved in flowering and seed-producing plants and not in flowerless ferns, the scientist continues. It remains fascinating though, that even without apparent indirect defenses bracken ferns successfully colonize our planet to this day. [JWK/AO]

Original Publication:
Venkatesan Radhika, Christian Kost, Gustavo Bonaventure, Anja David, Wilhelm Boland (2012). Volatile emission in bracken fern is induced by jasmonates but not by Spodoptera littoralis or Strongylogaster multifasciata herbivory. PLOS ONE, 20. November 2012; doi:10.1371/journal.pone.0048050

http://dx.doi.org/10.1371/journal.pone.0048050

Further Information:
Prof. Dr. Wilhelm Boland, MPI Chemical Ecology, boland@ice.mpg.de, +49 (0)3641 571201

Picture Requests:
Angela Overmeyer M.A., +49 3641 57-2110, overmeyer@ice.mpg.de
or download from http://www.ice.mpg.de/ext/735.html

Dr. Jan-Wolfhard Kellmann | Max-Planck-Institut
Further information:
http://www.ice.mpg.de
http://dx.doi.org/10.1371/journal.pone.0048050

More articles from Life Sciences:

nachricht Transport of molecular motors into cilia
28.03.2017 | Aarhus University

nachricht Asian dust providing key nutrients for California's giant sequoias
28.03.2017 | University of California - Riverside

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Periodic ventilation keeps more pollen out than tilted-open windows

29.03.2017 | Health and Medicine

Researchers discover dust plays prominent role in nutrients of mountain forest ecoystems

29.03.2017 | Earth Sciences

OLED production facility from a single source

29.03.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>