Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Africa: working towards aflatoxin-resistant groundnut varieties

16.03.2007
Groundnut is of undeniable nutritional importance in the Sahel countries, where few crops have as many nutritional or financial advantages. However, it is susceptible to aflatoxin, a highly toxic substance produced by the fungus Aspergillus flavus.

Infection is favoured by water stress towards the end of the cycle, and African regions regularly hit by drought, such as Senegal, Niger and Mali, are thus at particular risk. This brings serious health risks, such as liver cancer, as local populations may consume large quantities of contaminated products. Moreover, with the tightening of European health regulations, the export value of groundnut has dropped considerably, which means a financial risk for the countries concerned. To reverse this trend, it is vital to prevent contamination in the field and at every stage of marketing.

However, until now, varietal breeding programmes have failed to develop groundnut cultivars that are aflatoxin resistant and at the same time have high agronomic potential. In an attempt to find a solution, researchers are studying how the plant's resistance mechanisms work in the event of drought. To this end, a European project entitled "New tools for groundnut aflatoxin control in Sahel Africa", headed by CIRAD, has just been completed. In particular, it enabled the development of methodologies for improving varietal screening and growing groundnut under rainfed conditions, to reduce aflatoxin contamination both in the field and postharvest.

Groundnut seed ripening rate: a key criterion

Two reference varieties were chosen for study: a cultivar that gives average yields under drought conditions but has good aflatoxin resistance, and another that is higher-yielding but more susceptible to the fungus. Both varieties are widely distributed in Senegal and a large part of sub-Sahelian Africa. The approach taken consisted in studying them under different environmental conditions: under water stress, in the field, in glasshouses, etc. The researchers studied the varieties on an agronomic and physiological, and also biochemical and molecular, level.

One of the main results of the project concerned seed ripening rate: this is a key criterion in groundnut tolerance of aflatoxin contamination. Short-cycle varieties that produce small seeds that ripen quickly are more resistant. Moreover, water stress towards the end of the cycle disrupts the lipid metabolism of the susceptible cultivar more than that of the resistant cultivar. Fatty acid composition differs depending on whether or not the variety is aflatoxin-resistant, and the fatty acid metabolism can thus be assumed to be another parameter linked to groundnut resistance mechanisms prior to harvest.

With a view to groundnut varietal improvement, five genes of interest in terms of aflatoxin resistance were identified, cloned and studied. For most of them, this was the first time they had been sequenced and studied in groundnut. Some are involved in the lipid metabolism. The results suggest that groundnut has cell protection mechanisms to limit damage due to the dry season. Moreover, once water is available again, the crop has repair mechanisms. A study of expression of these five genes showed that they were all regulated by the water deficit. Moreover, transgenesis techniques are available for groundnut that could be used to integrate them into the varieties to be improved.

Good agricultural practice to prevent contamination

Furthermore, varieties with improved drought resistance have been developed from an aflatoxin-resistant parent and are currently being disseminated within the production zone. Various studies of good practices that may control contamination before and after harvest have been conducted in conjunction with farmers. They revealed a change in product degradation as it makes its way along the production chain. As a result, the researchers opted to set up a contamination risk analysis system, based on the "from farm to fork" concept, at every stage of the production chain, from production to marketing. In particular, the system concerns the choice of variety, treating crop storage facilities against infestation and the effect of using quicklime or manure to control infestation.

The results of this work are already being applied through an operation to develop a quality groundnut production chain in Senegal. The approach taken is participatory and based on analysing market demand (local industry, the export market, etc). One of the aims is to implement a system of fair contracts between producers' organizations and the private sector, so as to optimize market value. The operation is being led by CIRAD, in partnership with the main Senegalese producers' organization (ASPRODEB), with European Union funding.

Helen Burford | alfa
Further information:
http://www.cirad.fr/en/actualite/communique.php?id=644

More articles from Agricultural and Forestry Science:

nachricht Light green plants save nitrogen without sacrificing photosynthetic efficiency
21.11.2017 | Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign

nachricht Filling intercropping info gap
16.11.2017 | 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: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Previous evidence of water on mars now identified as grainflows

21.11.2017 | Physics and Astronomy

NASA's James Webb Space Telescope completes final cryogenic testing

21.11.2017 | Physics and Astronomy

New catalyst controls activation of a carbon-hydrogen bond

21.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>