SWITZERLAND – Researchers at the University of Basel have revealed how corn plants possess a natural defense mechanism against arsenic toxicity in contaminated soil.

This finding holds immense promise for mitigating the harmful effects of arsenic accumulation in the food chain, particularly in regions with prevalent soil contamination, such as southeastern Asian countries and certain areas in Switzerland.

Arsenic, a toxic metalloid found naturally in soil and water, poses significant health risks when it accumulates in the food chain.

Notably, arsenic-contaminated soils are widespread globally, with regions like Bangladesh, Vietnam, and China facing substantial challenges. Even Switzerland contends with localized arsenic hotspots, exemplified by soil in Liesberg, Baselland.

Led by Professor Klaus Schlaeppi, researchers investigated how corn plants combat arsenic uptake, crucially uncovering the role of benzoxazinoids. These compounds, prevalent in grasses like corn and wheat, are released into the soil via the roots, acting as a protective shield against arsenic toxicity.

In rigorous experiments, corn plants were grown in arsenic-free soil and soil with elevated arsenic levels. Parallel studies were conducted with genetically modified corn plants unable to produce benzoxazinoids.

The results unequivocally demonstrated that benzoxazinoid-producing corn exhibited superior growth in arsenic-containing soil and accumulated significantly less arsenic in their biomass compared to the mutant plants.

Mechanism unveiled

Further analysis revealed that the protective effect of benzoxazinoids was not mediated by root microbiota but rather through chemical transformations in the soil. Benzoxazinoids were found to alter the chemical form of arsenic, rendering it less available for uptake by plant roots, thus preventing its entry into the food chain.

These findings hold profound implications for agriculture in arsenic-contaminated regions. By cultivating plant varieties with enhanced benzoxazinoid production, it may be possible to minimize arsenic uptake and mitigate health risks associated with arsenic exposure.

Such hyper-emitting plants could be developed through traditional breeding methods or targeted genetic modifications, offering a sustainable solution to a pressing environmental and public health challenge.

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