Scientists at the ICRISAT have discovered a hitherto unknown self-defence mechanism in some peanuts that helps it in fighting fungal infections. This could result in the development of a natural defence mechanism not just in other varieties of peanuts but also in other crops.

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Peanut is vulnerable to Aspergillus infection and subsequent aflatoxin contamination.

Aflatoxin contamination caused by Aspergillus flavus which significantly threatens food safety and human health. Resistance to aflatoxin is a highly complex and quantitative trait, but the underlying molecular and biochemical mechanisms are poorly understood.

The present study aims to identify the resistance-related metabolites in groundnut that influence the defense mechanism against aflatoxin.

“The study uncovered the biochemical processes that lead to the thickening of the secondary cell wall, providing greater resistance to the fungal infection caused by Aspergillus flavus,” an ICRISAT (International Crops Research Institute for Semi-Arid Tropics). 

Aflatoxin, a potent carcinogen and toxin, accumulates in a variety of food crops such as cereals, oilseeds, pulses and nuts due to infection by Aspergillus species. Aflatoxin contamination poses a significant global challenge, impacting food safety, human health and the economy.

“Strict government regulations on the permissible levels of aflatoxin in food commodities significantly impact the food market and export economies, especially in developing countries,” it said.

While various physical and chemical methods exist to combat, minimise and manage aflatoxin contamination, developing more resistant varieties, offers the most economical solution by addressing the problem at its root.

This study offers insights that will be pivotal for breeding groundnut varieties that are fully resistant to Aspergillus infection in the future.  

“ICRISAT’s efforts, ranging from low-cost aflatoxin detection assays to post-harvest management practices, having revitalised export economies, particularly in Malawi. This study is crucial for advancing research aimed at eliminating the issue at its source, saving both cost and effort,” Jacqueline Hughes, Director-General of ICRISAT, said.

For this study, ICRISAT researchers used a metabolomics-based systems biology approach to understand the biochemistry behind increased peanut resistance to Aspergillus infection for the first time. The study reports the linkage between two specific metabolites and the level of resistance exhibited by peanut varieties.

Also read: Indian groundnuts gaining overseas markets on robust SE Asia demand

“The findings of this study highlight the important role secondary thickening of cell walls plays in reducing infection of seed in the field. If we can combine this with other mechanisms, which further decrease infection in peanut, we can really begin to move towards an aflatoxin-free peanut, ensuring the production of safe, toxin-free food,” Sean Mayes, Global Research Program Director (Accelerated Crop Improvement), said. 

“This methodology is not just confined to breeding more resistant groundnut varieties but can provide a wider understanding of similar resistance mechanisms across a broad spectrum of food crops such as cereals, oilseeds and nuts, which are highly susceptible to contamination from aflatoxin and other mycotoxins,” Yogendra Kalenahalli, the study’s lead author of the study, said.

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