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
Raiding the rape field
23.05.2018 | Julius-Maximilians-Universität Würzburg
New technique reveals details of forest fire recovery
17.05.2018 | DOE/Brookhaven National Laboratory
A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.
The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
24.05.2018 | Ecology, The Environment and Conservation
24.05.2018 | Medical Engineering
24.05.2018 | Physics and Astronomy