Featured Research

from universities, journals, and other organizations

Drought Reduces Nitrogen-fixing In Legumes

Date:
February 4, 2005
Source:
Elhuyar Fundazioa
Summary:
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.

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”.

<b>Nitrogen-fixing and drought</b>

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.

<b>Perception of water stress</b>

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


Story Source:

The above story is based on materials provided by Elhuyar Fundazioa. Note: Materials may be edited for content and length.


Cite This Page:

Elhuyar Fundazioa. "Drought Reduces Nitrogen-fixing In Legumes." ScienceDaily. ScienceDaily, 4 February 2005. <www.sciencedaily.com/releases/2005/02/050204114635.htm>.
Elhuyar Fundazioa. (2005, February 4). Drought Reduces Nitrogen-fixing In Legumes. ScienceDaily. Retrieved April 18, 2014 from www.sciencedaily.com/releases/2005/02/050204114635.htm
Elhuyar Fundazioa. "Drought Reduces Nitrogen-fixing In Legumes." ScienceDaily. www.sciencedaily.com/releases/2005/02/050204114635.htm (accessed April 18, 2014).

Share This



More Plants & Animals News

Friday, April 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Vermont Goat Meat Gives Refugees Taste of Home

Vermont Goat Meat Gives Refugees Taste of Home

AP (Apr. 18, 2014) — Dairy farmers and ethnic groups in Vermont are both benefiting from a unique collaborative effort that's feeding a growing need for fresh and affordable goat meat. (April 18) Video provided by AP
Powered by NewsLook.com
The Great British Farmland Boom

The Great British Farmland Boom

Reuters - Business Video Online (Apr. 17, 2014) — Britain's troubled Co-operative Group is preparing to cash in on nearly 18,000 acres of farmland in one of the biggest UK land sales in decades. As Ivor Bennett reports, the market timing couldn't be better, with farmland prices soaring over 270 percent in the last 10 years. Video provided by Reuters
Powered by NewsLook.com
Flamingo Frenzy Ahead of Zoo Construction

Flamingo Frenzy Ahead of Zoo Construction

AP (Apr. 17, 2014) — With plenty of honking, flapping, and fluttering, more than three dozen Caribbean flamingos at Zoo Miami were rounded up today as the iconic exhibit was closed for renovations. (April 17) Video provided by AP
Powered by NewsLook.com
Change of Diet Helps Crocodile Business

Change of Diet Helps Crocodile Business

Reuters - Business Video Online (Apr. 16, 2014) — Crocodile farming has been a challenge in Zimbabwe in recent years do the economic collapse and the financial crisis. But as Ciara Sutton reports one of Europe's biggest suppliers of skins to the luxury market has come up with an unusual survival strategy - vegetarian food. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins