Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How acid finds its way into wine

10.02.2010
If it were not for proton pumps in plants, there would be no acid in wine. These pumps are important generally for plant vitality, as researchers from Würzburg and Heidelberg report in the renowned journal "Proceedings" of the Academy of Sciences in the USA.

During photosynthesis, plants tend to produce more nutrients than they actually need. They store the surplus in various places, including their vacuoles. These storage chambers account for 70 to 90 percent of the volume inside cells. They are filled with an aqueous solution of ions and nutrients and are surrounded by a membrane.

Sugar beets accumulate sugar in their vacuoles, while grapes and other fruits store not just sugar but fruit acids as well. What contents fill the vacuoles depends on how their membranes are equipped with special transporters. After all, sugar and acids do not simply end up in the storage chambers - the plant conveys them there purposefully, and the only way it can do this is with the help of proton pumps.

Acidity of wine is determined by protons

Under the application of energy, these pumps propel protons into the vacuole. "The acidity of wine, for instance, is due entirely to the protons accumulated in the vacuolar sap," says Professor Rainer Hedrich, biophysicist at the University of Würzburg. Some 90 percent of grape juice comes from vacuoles.

The activity of the pumps ensures that the vacuole contains many more protons than the cell sap. This concentration gradient is a source of energy - the protons force their way back out of the overcrowded vacuole, in the same way as air out of a firmly inflated balloon. This is where the special transporters that sit in the vacuolar membrane come into play: they use the energetically favorable release of protons to carry sugar and other molecules into the vacuole at the same time according to the exchange principle.

"This gradual conversion of energy is a universal principle in biology. It enables storage organs such as sugar beets and fruits, but also leaves, to accumulate a hundred times as much content and more," explains Hedrich. In this way, the plants build up valuable resources for times of shortage - at night, for example, when photosynthesis comes to a halt.

The importance of proton pumps to plant vitality and productivity is described by Rainer Hedrich together with Professor Karin Schumacher from the University of Heidelberg in the journal "Proceedings". The two scientists work together as members of a supra-regional vacuolar research group funded by the German Research Foundation (DFG).

Two different proton pumps fill the vacuole

There are two types of proton pump in the vacuolar membrane. One of them needs the high-energy phosphate compound ATP as a fuel for its activity, the other uses so-called pyrophosphate (PP).

Rainer Hedrich was the first person to measure the activity of both pumps back in 1986 as a post-doctoral student at the Max Planck Institute for Biophysical Chemistry in Göttingen. But the connection between the two types of pump as well as their relative importance have always been largely unknown.

To answer these questions, Hedrich and Schumacher decided to inhibit the genes for the ATP-dependent proton pump on the model plant Arabidopsis, which is popular among geneticists. This left just the other type of pump still active in the plants.

Without pumps: stress lowers productivity

"Under ideal growing conditions, the absence of the ATP-dependent pump had no affect at first on whether or not the plants flourished," explains Hedrich. However, when the plants were exposed to certain stress conditions, such as nitrogen deprivation and high levels of heavy metals, their growth and productivity suffered considerably.

It was not until the plants were placed under difficult living conditions that the absence of these pumps became noticeable. It would appear that with only one type of proton pump the plant can no longer fill its vacuoles with ions and metabolites well enough to be adequately armed to cope with stress.

Goal: to produce plants with greater stress resistance

Spurred on by this discovery, Rainer Hedrich and Karin Schumacher's next goal is to try to produce plants that create certain proton pumps in increased numbers, making them better equipped to survive stress periods.

Arabidopsis V-ATPase activity at the tonoplast is required for efficient nutrient storage but not for sodium accumulation. Melanie Krebs, Diana Beyhl, Esther Görlich, Khaled A. S. Al-Rasheid, Irene Marten, York-Dieter Stierhof, Rainer Hedrich, and Karin Schumacher; Proc Nat Acad Sci (USA), published online before print January 26, 2010; doi:10.1073/pnas.0913035107

Contact

Prof. Dr. Rainer Hedrich, phone +49 931 31 86100, hedrich@botanik.uni-wuerzburg.de

About Rainer Hedrich

With his work on ion channels and pumps, Professor Rainer Hedrich has been one of the world's most eminent scientists in the field of membrane transport for more than 20 years now. The Faculty of 1000 regularly classifies his work as especially worth reading. The Animal and Plant Sciences section of the ISI Web of Knowledge names him among researchers who are quoted with particular frequency. It was not until January 2010 that the European Research Council awarded him one of the coveted ERC Advanced Grants: this award comes with 2.5 million euros.

Rainer Hedrich is no stranger to analyzing ion channels and pumps using highly sensitive biophysical processes. He managed to obtain functional evidence of ion channels in plants for the first time during his doctorate back in 1984 in the laboratory of Nobel Prize winner Professor Erwin Neher. Since this discovery with the help of the patch clamp technique, he has identified and characterized quite a number of different ion channel types and pumps both in the plant cell membrane and in the membranes of various cell organelles. His expertise in the molecular and biophysical analysis of transport processes makes him a sought-after partner to work with in special research areas, graduate colleges, and national as well as international research consortia.

Robert Emmerich | idw
Further information:
http://www.uni-wuerzburg.de/

More articles from Agricultural and Forestry Science:

nachricht Plasma-zapping process could yield trans fat-free soybean oil product
02.12.2016 | Purdue University

nachricht New findings about the deformed wing virus, a major factor in honey bee colony mortality
11.11.2016 | Veterinärmedizinische Universität Wien

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

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

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>