Sulfur belongs to the macro-nutrients and has a variety of tasks in plants. It is not only involved in the synthesis of substances which are important for plant growth, but is also an important component of substances whose function is the defence against diseases and pests. Currently, a research group at the Max Planck Institute of Molecular Plant Physiology, led by Dr. R Hoefgen, published in cooperation with Dr. Akiko Maruyama-Nakashita and her group (Kyushu University,Japan) in Science Advances how plants determine under sulfur limiting conditions that sulfur is primarily used for growth processes and not for the production of substances which protect them against diseases and pests.
Sulfur is Essential for Plants
Sulfur, like nitrogen, phosphorus, potassium, calcium, and magnesium, is one of the macro-nutrients. Unlike micronutrients, plants need higher amounts of them for development and growth. In case of sulfur deficiency yield losses occur. This is due to the fact that sulfur affects e.g. the synthesis of carbohydrates and is a component of proteins, since the amino acids methionine and cysteine contain sulfur.
However, sulfur does not only play a role in primary metabolism, that is, where energetic substances such as sugars, proteins or fats are formed which are important for growth but sulfur is also a constituent of secondary metabolites that are involved in the synthesis of vitamins and flavours.
A special group of secondary metabolites is found in cruciferous plants such as rapeseed, cabbage, mustard, and horseradish, providing the characteristic bitter taste and pungency. These compounds are referred to as glucosinolates or mustard oil glycosides. Glucosinolates act in plants as protectants against diseases and pest infestation. They are not of much help against humans, though, as we like to eat cabbage, broccoli and co.
Pest Control on the One Hand - Pharmacological Activity on the Other
The pungency and health promoting properties of the cruciferous plants, mentioned above, are due to isothiocyanates derivatives, also known as ‘mustard oils’ produced from glucosinolates when the plant tissues are chewed by humans, pests or insects. Conversion of glucosinolates into mustard oils requires special enzymes that are spatially separated from the glucosinolates in the plant cell. When an insect nibbles on the plant the enzyme and the glucosinolates come together and produce mustard oils. These pungent compounds then repel the insects from the plant and protect it from further infestation.
Produced by the plant for defence, however, these compounds could also have positive medicinal effects. Fayezeh Aarabi, Ph.D. student in the group led by Dr. Hoefgen and the first author of the paper explains: "Mustard oils have antibacterial effects, anticancer properties and, according to the latest research, they could also have antidiabetic effects and activate enzymes of the detoxification metabolism. In order to be able to use the glucosinolates pharmacologically, it is obviously of great interest to understand how their production is regulated in the plant. This is exactly what we have been working on in collaboration with Japanese scientists and now we published our results."
Regulation of Glucosinolate Production
If a cruciferous plant such as cabbage, rapeseed or the target of investigation in this project, Arabidopsis thaliana, is sufficiently supplied with sulfur, glucosinolates are formed. The production of these metabolites is controlled by so-called transcription factors. Transcription factors are proteins which can bind directly to the DNA. Their task is to ensure that genes are transcribed into RNA and proteins are synthesized, which in turn ensure that the ingredients required by the plant are produced. In the present case the glucosinolates.
Dr. Rainer Hoefgen comments: "With sufficient sulfur supply, the plants can form both the substances necessary for growth and glucosinolates. If the plants receive too little sulfur, the substances essential for growth are formed, while the plant reduces the production of glucosinolates. Growth and reproduction are more important for the plant than accumulation of substances for pest control."
The identified Sulfur Deficiency Induced genes, so called SDI1 and SDI2 are responsible for reducing the production of glucosinolates. These genes are highly expressed if sulfur deficiency occurs. As a result, the proteins SDI1 and SDI2 are formed which form a complex with a transcription factor of the glucosinolate pathway, namely MYB28. This complex leads to the fact that the transcription factor can no longer perform its function and consequently fewer enzymes of the glucosinolate biosynthesis pathway are synthesized and thus, also less glucosinolates are produced.
"Our new understanding of the regulation of glucosinolate production is an important step to better control the synthesis of medically effective ingredients in plants, either through improved and optimized sulfur fertilization or the development of new breeding strategies," says Fayezeh Aarabi.
Dr. Rainer Höfgen
Max Planck Institute of Molecular Plant Physiology
Tel. +49 331 567 8205
Max Planck Institute of Molecular Plant Physiology
Tel. +49 331 567 8310
Fayezeh Aarabi, Miyuki Kusajima, Takayuki Thoge, Tomokazu Konishi, Tamara Gigolashvili, Makiko Takamune, Yoko Sasazaki, Mutsumi Watanabe, Hideo Nakashita, Alisdair R. Fernie, Kazuki Saito, Hideki Tagalhashi, Hans-Michael Hubberten, Rainer Hoefgen, Akiko Maruyama-Nakashita
Sulfur-defieciency-induced repressor proteins optimize glucosinolate biosynthesis in plants
Science Advances, 2016; 2 (10):e1601087, eCollection; doi: 10.1126/sciadv.1601087
http://www.mpimp-golm.mpg.de/2090184/growth-or-defence (press release)
http://www.mpimp-golm.mpg.de/2168/en (Website of the Institute)
Dipl. Ing. agr. Ursula Ross-Stitt | Max-Planck-Institut für Molekulare Pflanzenphysiologie
Progress in Super-Resolution Microscopy
17.12.2018 | Julius-Maximilians-Universität Würzburg
Communication between neural networks
17.12.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau
Researchers from the University of Basel have reported a new method that allows the physical state of just a few atoms or molecules within a network to be controlled. It is based on the spontaneous self-organization of molecules into extensive networks with pores about one nanometer in size. In the journal ‘small’, the physicists reported on their investigations, which could be of particular importance for the development of new storage devices.
Around the world, researchers are attempting to shrink data storage devices to achieve as large a storage capacity in as small a space as possible. In almost...
The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.
Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...
What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...
A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.
The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...
A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.
Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...
12.12.2018 | Event News
10.12.2018 | Event News
06.12.2018 | Event News
17.12.2018 | Studies and Analyses
17.12.2018 | Life Sciences
17.12.2018 | Power and Electrical Engineering