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ICRISAT researchers discover peanut defense mechanisms, offering hope for disease resistance

Fluorescent microscope images depicting secondary cell wall thickening in resistant groundnut variety (left) and susceptible variety (right). (Image source: ICRISAT))

According to a recent study by ICRISAT researchers, certain peanut varieties were found to exhibit natural resistance to fungal infection, which holds promise for the future development of disease-resistant peanut varieties

The study uncovered the biochemical processes that lead to the thickening of the secondary cell wall, thus providing greater resistance to the fungal infection caused by Aspergillus flavus. Infection by this fungus results in the accumulation of a potent carcinogen and toxin called aflatoxin in a variety of food crops including cereals, pulses and oilseeds, thereby posing a significant global challenge, impacting food safety, human health, and the economy. Despite the existance of physical and chemical methods to combat, minimise and manage aflatoxin contamination, the most economical solution is to address the problem at its root by developing more resistant varieties. 

A metabolomics-based systems biology approach was used to understand the biochemistry behind increased peanut resistance to Aspergillus infection. The study reported the linkage between the two key metabolites namely, hydroxycinnamic acid amides (HCAAs) and lignin, and the level of resistance exhibited by peanut varieties. The precursor levels of these compounds, responsible for strengthening the secondary cell wall, were found to be higher in the resistant genotype. 

“The findings of this study highlight the important role secondary thickening of cell walls plays in reducing infection of seed in the field," stated Sean Mayes, global research programme director – Accelerated Crop Improvement. "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."

For more information, visit: https://www.icrisat.org/