Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Drought reduces nitrogen-fixing in legumes

04.02.2005


In drought conditions, the capacity for retaining carbon in legume nodules is limited and this may be the reason why there is a drop in nitrogen-fixing in legumes under these conditions. This was the conclusion of María Dolores Gálvez in defending her PhD thesis at the Public University of Navarre. Her PhD was entitled, “Nodule metabolism in Pisum sativum L. in response to water stress: carbon/nitrogen interactions and the possible molecules involved in the modulation of the response”.



Nitrogen-fixing and drought

Biological nitrogen-fixing is a process of great agricultural and ecological interest, given that nitrogen, after water and carbon, is the nutrient that most limits vegetable growth and crop production. This process is particularly sensitive to adverse environmental conditions, such as water stress or drought. This is why María Dolores Gálvez’s PhD was aimed at investigating how the regulation of biological nitrogen-fixing is carried out under drought conditions.


The reduction of atmospheric nitrogen to ammonia - or nitrogen-fixing - can only be carried out by procariots. Amongst these, the ones generically known as rhizobes are capable of establishing symbiosis with legume plants giving rise to a new structure: the nodule.

On the one hand, the plant benefits from the micro-organism, that takes on the task of capturing nitrogen from the air and converting it into ammonia in such a way that the plant can use it. This ammonia is incorporated into carbon skeletons in order to form aminoacids and proteins. On the other hand, the micro-organism obtains nutrients necessary for its growth from the plant.

Under drought conditions, a reduction in nodule sacarose synthesis activity was observed. This drop occurred simultaneously with a decrease in nitrogen-fixing, enabling the establishment of a high correlation between both processes in adverse conditions. As a consequence of the inhibition of sacarose synthesis activity, a drop in the concentration of phosphate sugars and organic acids was also observed, indicating a decrease in carbon flow in the nodules, a drop which, in turn, limits the supply of carbon to the bacteroid and the capacity of the bacteroid to fix nitrogen thus affected.

Perception of water stress

Wishing to investigate the process of perception and transduction of water stress that leads to the inhibition of nitrogen-fixing, María Dolores Gálvez also studied abscisic acid and species of activated oxygen as possible molecules involved in the regulation of nitrogen-fixing.

The results obtained on the exogenous application of abscisic acid suggested the existence of at least two different mechanisms for the regulation of biological nitrogen-fixing depending on how the stress evolves. In situations in which the stress is produced gradually, a route that is independent of abscisic acid is activated, involving the inhibition of sacarose synthesis activity; in situations where the stress occurs rapidly and intensely, another route, dependent on abscisic acid, involving control through leghaemoglobine/oxygen, is activated.

In order to analyse the possible involvement of species of activated oxygen in the modulation of nitrogen-fixing, the exogenous application to plants exposed to water stress of abscisic acid - a natural antioxidant – was decided upon. Treatment with exogenous abscisic acid, carried out under conditions of water stress, played a beneficial role on the protein content of the plant. Likewise, a recovery in the total activity of the metabolism carbonand nitrogen enzymes in the nodules was observed.

Moreover, the application of abscisic acid did not reverse the negative effect of the water stress in and it is thus not possible to relate species of activated oxygen with the regulation of nitrogen-fixing. In this context, the decrease in of nitrogen-fixing happens in association with a limitation in the carbon flow in the nodules, caused by the inhibition of sacarose synthesis activity under these conditions.

Thus, the signs involved in the perception and the transduction route that lead to a decrease in biological nitrogen-fixing in water stress conditions are complex and need to be studied further in order to understand the mechanisms for the regulation of biological nitrogen-fixing

Garazi Andonegi | alfa
Further information:
http://www.basqueresearch.com
http://www.elhuyar.com

More articles from Agricultural and Forestry Science:

nachricht New study shows producers where and how to grow cellulosic biofuel crops
17.01.2018 | University of Illinois College of Agricultural, Consumer and Environmental Sciences

nachricht Robotic weeders: to a farm near you?
10.01.2018 | American Society of Agronomy

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: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

Im Focus: A thermometer for the oceans

Measurement of noble gases in Antarctic ice cores

The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Gran Chaco: Biodiversity at High Risk

17.01.2018 | Ecology, The Environment and Conservation

Only an atom thick: Physicists succeed in measuring mechanical properties of 2D monolayer materials

17.01.2018 | Physics and Astronomy

Fraunhofer HHI receives AIS Technology Innovation Award 2018 for 3D Human Body Reconstruction

17.01.2018 | Awards Funding

VideoLinks
B2B-VideoLinks
More VideoLinks >>>