Plants produce a large variety of substances that are often highly prized by humans, such as caffeine and essential oils. Many substances derived from plants add special flavors to meals, and quite a number are regarded as health-promoting. This also applies to mustard oils, which make mustard spicy and give brassicas their unique aroma.
When caterpillars or other hungry insects feed on glucosinolate-containing plants like broccoli, the glucosinolates get in contact with the enzyme myrosinase, that releases mustard oils. These ward off the insects. Picture: Dietmar Geiger
Mustard oils are reputed to be able to prevent cancer. There are various signs to support this notion. “For example, it is known that the constituents of broccoli kill off the bacterium Helicobacter pylori, which can trigger stomach ulcers and cancer,” says Professor Rainer Hedrich, plant scientist at the University of Würzburg.
Mustard oils as protection against enemies
Of course, plants do not synthesize such special constituents to protect humans. Instead, they use them to keep microbes and other enemies at bay. Often, they only use their chemical mace in an emergency. The pungent and spicy mustard oils, for instance, are only produced if the plant is injured, say, by an insect munching on it. Only then do the precursors of the mustard oils, the glucosinolates, come into contact with an enzyme that releases the mustard oils. This effect is familiar to anyone who has ever bitten into a radish.
Hungry insects tend to seek out the nutritious leaves and seeds. So, it is no wonder that the plant accumulates particularly large quantities of glucosinolates in these parts. The leaves can produce the deterrents themselves, but the maturing seeds cannot. “They have to import the glucosinolates, and this is not possible without special transport proteins,” says Professor Dietmar Geiger, plant physiologist at the University of Würzburg.
Prospects for agriculture
Until recently, virtually nothing was known about these vital transporters and their genes. But a research team from Copenhagen, Würzburg, and Madrid has now identified them. The results have been published in the journal “Nature”, giving them great prominence because they could have a far-reaching impact on agriculture.
Hedrich explains: “This paves the way for deliberately cultivating plants whose glucosinolate content and composition are tailored to the health of humans.” One such plant might be broccoli, optimized to combat the stomach bacterium Helicobacter.
How the results were attained
As the object of their analysis, the international research team used the plant Arabidopsis thaliana. Scientists know all there is to know about the genetic material of this model plant; it is also a “little sister” of cabbage, mustard, and rapeseed – it too contains glucosinolates and their transporters.
How did the scientists proceed? First of all, they applied a cellular biological approach. Using eggs from the South African clawed frog as a “test tube”, they conducted an assay to identify the genes needed to import and accumulate glucosinolates. In the end, the Danish team attributed this to two genes.
It was now the turn of the transporter specialists from Würzburg with their biophysical research methods – Professor Dietmar Geiger, in particular. They shed light on the mechanism that is used by these nanomachines sitting in the cell membrane to draw energy and transport the glucosinolates.
In the meantime, Barbara Ann Halkier from Copenhagen had isolated an Arabidopsis mutant in which neither transporter works: the plant had no glucosinolates whatsoever in its seeds. This proved that the researchers had indeed deciphered the genetic code and the function of the glucosinolate transporters that are so important to the survival of plants containing mustard oil.
The international research team
The team led by Professor Barbara Ann Halkier at the University of Copenhagen comprises experts in the field of glucosinolate metabolism. Professor Rainer Hedrich and Professor Dietmar Geiger from Würzburg are specialists in transport proteins in plants. The final member of this group of experts is former Würzburg plant scientist Ingo Dreyer, who is now a professor at the University of Madrid.
“NRT/PTR transporters essential for allocation of glucosinolate defense compounds to seeds”, Hussam Hassan Nour-Eldin, Tonni Grube Andersen, Meike Burow, Svend Roesen Madsen, Morten Egevang Jørgensen, Carl Erik Olsen, Ingo Dreyer, Rainer Hedrich, Dietmar Geiger, and Barbara Ann Halkier, Nature (2012), published online 05 august, DOI: 10.1038/nature11285
Prof. Dr. Rainer Hedrich, Department of Botany I (Molecular Plant Physiology and Biophysics) at the University of Würzburg, T +49 (0)931 31-86100, email@example.com
Robert Emmerich | idw
Fingerprint' technique spots frog populations at risk from pollution
27.03.2017 | Lancaster University
Parallel computation provides deeper insight into brain function
27.03.2017 | Okinawa Institute of Science and Technology (OIST) Graduate University
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...
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...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
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...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
27.03.2017 | Earth Sciences
27.03.2017 | Life Sciences
27.03.2017 | Life Sciences