Dandelions are troublesome weeds that are detested by most gardeners. Yet dandelions also have many insect enemies in nature. However, they are able to protect themselves with their latex, a milky, bitter-tasting sap. Scientists at the Max Planck Institute for Chemical Ecology in Jena, Germany, and the University of Bern, Switzerland, have now demonstrated that a single compound in the latex protects dandelion roots against voracious cockchafer larvae. Thus, latex plays a crucial role in dandelion defense against root feeders. (PLOS Biology, January 2016, Open Access)
Dandelions are survival experts
The larva of a cockchafer Melolontha melolontha attacks the roots of a dandelion.
Meret Huber / Max Planck Institute for Chemical Ecology, PLOS Biology
Dandelions (Taraxacum officinale agg.) are well-known plants of European and Asian origin that have spread around most of the temperate world. Children love their yellow flowers and even more the fluffy seed heads with their parachute-like seeds that can travel long distances by wind. Young plants grow with such force that they can penetrate even asphalt. Therefore dandelions have become a symbol for survival in modern cities.
In fields and meadows, the plant must fend off many herbivores, among them cockchafer larvae. The common cockchafer (Melolontha melolontha) spends the first three years of its life cycle underground as a grub feeding on the roots of different plants. One of its favorite foods is dandelion roots.
Like many other plants, dandelions produce secondary metabolites to protect themselves against herbivores. Some of these defenses, such as terpenes and phenols, are of pharmaceutical interest and are considered promising anti-cancer agents. The most important dandelion metabolites are bitter substances which are especially found in a milky sap called latex, a substance found in almost ten percent of all flowering plants.
Why dandelion latex is bitter
Scientists from the Department of Biochemistry and their colleagues from the University of Bern have now taken a closer look at dandelion latex. The scientists found the highest concentrations of the bitter latex in the roots of dandelions. Dandelions need to protect their roots very fiercely because these are the main storage organs for nutrients which fuel growth early in the spring.
One single defensive chemical protects the plant
The scientists tested first whether latex compounds produced by dandelion roots were negatively associated with the development of cockchafer larvae. They also wanted to know whether these compounds had a positive effect on the fitness and reproductive success of dandelions under Melolontha melolontha attack. An analysis of the components of dandelion latex revealed that one single substance negatively influenced the growth of cockchafer larvae. This substance was identified as the sesquiterpene lactone, taraxinic acid β-D-glucopyranosyl ester (TA-G). When the purified substance was added to an artificial larval diet in ecologically relevant amounts, the grubs fed considerably less.
The researchers succeeded in identifying the enzyme and gene responsible for the formation of a precursor of TA-G biosynthesis, and so were able to engineer plants with lower TA-G. Roots of engineered plants with less TA-G were considerably more attacked by cockchafer larvae. The chemical composition of latex varies between different natural dandelion lines. A common garden experiment with different lines revealed that plants which produce higher amounts of TA-G maintained a higher vegetative and reproductive fitness when they were attached by cockchafer larvae. “For me, the biggest surprise was to learn that a single compound is really responsible for a defensive function,” says Jonathan Gershenzon, the head of the Department of Biochemistry at the Max Planck Institute in Jena. “The latex of dandelions and other plants consists of such a mixture of substances that it didn’t seem necessarily true that one chemical by itself had such a protective role against our study insect.”
The combination of approaches as a key to success
“It was clearly the combination of techniques that was crucial for the success of our studies,” explains Matthias Erb from the University of Bern who led the study. “Each approach has its weaknesses that were balanced by the strengths of the others. We think that this type of interdisciplinary research can be very powerful to understand biological systems.”
The scientists are now planning further experiments study the co-evolution of dandelions and their root herbivores in order of find out whether the presence of root-feeding insects has shaped the plant defensive chemistry in the course of evolution and whether the insects show adaptations to dandelion defenses. [AO]
Huber, M., Epping, J., Schulze Gronover, C., Fricke, J., Aziz, Z., Brillatz, T., Swyers, M., Köllner, T. G., Vogel, H., Hammerbacher, A., Triebwasser-Freese, D., Robert, C. A. M., Verhoeven, K., Preite, V. Gershenzon, J., Erb, M. (2016). A latex metabolite benefits plant fitness under root herbivore attack. PLOS Biology, DOI: 10.1371/journal.pbio.1002332. Open Access
Meret Huber, Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07743 Jena, Germany, +49 3641 57-1329, email@example.com
Matthias Erb, University of Bern, Institute of Plant Sciences, Altenbergrain 21, 3013 Bern, Switzerland, +41 31 631 8668, firstname.lastname@example.org
Jonathan Gershenzon, Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07743 Jena, Germany, +49 3641 57-1301, email@example.com
Contact and Media Requests:
Angela Overmeyer M.A., Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07743 Jena, +49 3641 57-2110, E-Mail firstname.lastname@example.org
Angela Overmeyer | Max-Planck-Institut für chemische Ökologie
Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs
16.01.2017 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Cholera bacteria infect more effectively with a simple twist of shape
13.01.2017 | Princeton University
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
17.01.2017 | Earth Sciences
17.01.2017 | Materials Sciences
17.01.2017 | Architecture and Construction