Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A one-way street for salt

21.09.2018

Barely heard of a couple of years ago, quinoa today is common on European supermarket shelves. The hardy plant thrives even in saline soils. Researchers from the University of Würzburg have now determined how the plant gets rid of the excess salt.

A growing world population means that more food is needed which in turn may require more land to grow food crops. More agriculture, however, results in increased irrigation, particularly for food crops such as maize and wheat – especially in dry regions. Combined with the use of fertilizer, this leads to salt accumulation in soils.


Quinoa stores salt in the bladder cells on its leaves.

Picture: Jennifer Böhm

To be able to use saline soils, naturally salt-tolerant plants, the so-called halophytes, are of great interest. The pseudo-cereal quinoa (Chenopodium quinoa) is one of them. Quinoa originated in the Andean region and is adapted to harsh environmental conditions. In the South American mountain range, the cereal-like plant has been used as a food crop for 7000 years. Gluten-free and high in vitamins, the edible seeds have now found their way into European supermarkets.

Quinoa uses bladder cells for desalination

Quinoa, which is rich in minerals and vitamins, sequesters excessive salt to hair-like bladder cells. This morphological adjustment makes the plant tolerant to saline conditions. These final storage sites for salt connected to the outer cell layer of the leaves prevent toxic levels of sodium chloride (NaCl), also known as table salt, from building up within the leaf tissue.

Led by Professor Rainer Hedrich from the University of Würzburg, an international team of researchers comprising scientists from Munich, Genoa (Italy), Hobart (Australia) and Shanghai (China) and Riyadh (Saudi Arabia) has now figured out the molecular mechanism of how bladder cells store salt. They have published their results in the journal Current Biology.

Salt transport from the soil into the salt bladder

When quinoa is exposed to saline soils, sodium and chloride ions travel from the root through the shoot and the leaves into the salt bladders where they are ultimately stored in vacuoles. On their way into the salt bladders, the ions have to overcome several membrane barriers. This is accomplished by transport proteins which are specialised for sodium (Na+) and chloride (Cl-) ions.

Compared to crops which are not salt-tolerant, these transport proteins do not have to be reassembled with increasing salt load, rather they are already in place before the stress begins. "This strategy enables quinoa to transfer the suddenly occurring salt immediately to the final storage without any further gene regulation steps," Hedrich says.

Sodium channel is a one-way street

The properties of this sodium channel not only assure that sodium ions are continuously transported from the leaf into the bladder cells where they can be stored in high concentration. "What's special about this mechanism is that it prevents backflow of sodium and hence the Na+ leakage into the leaves even when the stored sodium reaches very high levels," Dr. Jennifer Böhm, the first author of the study, says. The sodium channel thus functions as a safety valve, making it the key component of final salt storage in the salt bladders.

When the salt is in the leaves, the Na+ and Cl- ions need to be transported through the plasma membrane into the cytosol (intracellular fluid) of the salt bladders. Analogously to the sodium ions, the plant assures the directional transport of chloride ions into the cell.

In plants, rising sodium chloride levels in the cytosol are toxic for many metabolic processes. Therefore, quinoa sequesters the salt in membrane-enclosed vacuoles outside its metabolically active parts. This second membrane which sodium and chloride ions need to pass is called the tonoplast. Here, too, salt transport takes place in one direction only.

Transfer to final storage yet to be studied

"This study has provided fundamental insights that will allow us to selectively breed salt-tolerant crops in the future," Hedrich says. "We have shed light on the molecular components of salt storage. But we want to further investigate how the salt is transferred from the leaves to the final storage site," Böhm says. The salt has to be transported through a small tunnel-like connection, the stalk-like cells between salt bladders and leaf epidermis.

Wissenschaftliche Ansprechpartner:

Dr. Jennifer Böhm, Department of Botany I - Molecular Plant Physiology and Biophysics, T.: +49 931 31-89206, jennifer.boehm@uni-wuerzburg.de

Prof. Dr. Rainer Hedrich, Department of Botany I - Molecular Plant Physiology and Biophysics, T.: +49 931 31-86100, hedrich@botanik.uni-wuerzburg.de

Originalpublikation:

Understanding the Molecular Basis of Salt Sequestration in Epidermal Bladder Cells of Chenopodium quinoa, Jennifer Böhm, Maxim Messerer, Heike M. Müller, Joachim Scholz-Starke, Antonella Gradogna, Sönke Scherzer, Tobias Maierhofer, Nadia Bazihizina, Heng Zhang, Christian Stigloher, Peter Ache, Khaled A.S. Al-Rasheid, Klaus F.X. Mayer, Sergey Shabala, Armando Carpaneto, Georg Haberer, Jian-Kang Zhu and Rainer Hedrich, https://doi.org/10.1016/j.cub.2018.08.004

Gunnar Bartsch | Julius-Maximilians-Universität Würzburg
Further information:
http://www.uni-wuerzburg.de

More articles from Life Sciences:

nachricht Lethal combination: Drug cocktail turns off the juice to cancer cells
12.12.2018 | Universität Basel

nachricht Smelling the forest – not the trees
12.12.2018 | Universität Konstanz

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

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...

Im Focus: New Foldable Drone Flies through Narrow Holes in Rescue Missions

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...

Im Focus: Topological material switched off and on for the first time

Key advance for future topological transistors

Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...

Im Focus: Researchers develop method to transfer entire 2D circuits to any smooth surface

What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.

Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...

Im Focus: Three components on one chip

Scientists at the University of Stuttgart and the Karlsruhe Institute of Technology (KIT) succeed in important further development on the way to quantum Computers.

Quantum computers one day should be able to solve certain computing problems much faster than a classical computer. One of the most promising approaches is...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

New discoveries predict ability to forecast dementia from single molecule

12.12.2018 | Health and Medicine

CCNY-Yale researchers make shape shifting cell breakthrough

12.12.2018 | Physics and Astronomy

Pain: Perception and motor impulses arise in the brain independently of one another

12.12.2018 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>