Arsenic is a toxic element that accumulates in food when crops grow in
contaminated soil. A study conducted by the University of Basel has
discovered a mechanism used by corn plants to reduce arsenic uptake in a
special substance released into the soil by the plant's roots.



Arsenic-contaminated soils and waters are found in many parts of the world,
especially in southeastern Asian countries like Bangladesh, Vietnam, and
China. Switzerland has a few natural hot spots where arsenic is found in
above-average concentrations. According to Professor Klaus Schlaeppi of the
Department of Environmental Sciences at the University of Basel, arsenic
behaves chemically similar to phosphorus, an important nutrient that plants
take up through special transport channels in their roots. As arsenic enters
the plants through the roots, more toxic substance accumulates in the
biomass and gets into the food chain. This affects human health as high
arsenic exposure can cause neurological damage and cancer.



Schlaeppi's team found that corn reduces arsenic toxicity through compounds
known as benzoxazinoids. These substances are produced by most plants in the
botanical group of grasses, including corn and wheat. Corn produces large
quantities of benzoxazinoids, released into soil through the root system.
Schlaeppi added that there is evidence that corn takes up less arsenic than
other plant species. To test their hypothesis, the researchers grew corn
plants in soil without arsenic and with high levels of arsenic. They
performed the same experiment using corn plants that cannot produce
benzoxazinoids because of a genetic defect.



The results showed that benzoxazinoid-producing corn grew better in the
arsenic-containing soil and accumulated significantly less arsenic in its
biomass than the corn that did not exude benzoxazinoids. When the
researchers mixed benzoxazinoids into the arsenic-containing soil, the
mutant plants were also protected from arsenic toxicity.



[www.unibas.ch]-
toxicity-in-soil.html