21 July 2024
Corn reduces arsenic

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Corn’s Role in Reducing Arsenic Toxicity

Corn, a staple crop in many regions, has been found to play a crucial role in reducing arsenic toxicity in soil. When crops are grown in arsenic-contaminated soil, the toxic element can accumulate in the food chain, posing serious health risks to humans. However, a recent study conducted by researchers at the University of Basel has shed light on a mechanism employed by corn plants to mitigate arsenic uptake, highlighting the significance of a specific substance released into the soil by the plant’s roots.

Arsenic is a naturally occurring toxic metalloid that is prevalent in soils and waters globally, with hot spots found in various regions including southeastern Asian countries like Bangladesh, Vietnam, and China. Even Switzerland has areas with elevated concentrations of arsenic, such as the soil in Liesberg, Baselland. Professor Klaus Schlaeppi from the Department of Environmental Sciences at the University of Basel explains the challenge faced by plants in such environments, where arsenic chemically resembles phosphorus, an essential nutrient for plant growth. The similarity between arsenic and phosphorus allows arsenic to enter plants through the same transport channels in the roots, leading to its accumulation in the plant biomass and subsequent entry into the food chain, with detrimental effects on human health, including neurological damage and cancer.

Mechanism of Action: Benzoxazinoids in Corn

The researchers at the University of Basel, as reported in the journal PNAS, discovered that corn plants possess a defense mechanism against arsenic toxicity through the production of compounds called benzoxazinoids. These substances, commonly found in grasses like corn and wheat, are released into the soil via the plant’s root system. Corn, in particular, synthesizes significant amounts of benzoxazinoids, which play a crucial role in reducing arsenic uptake.

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To substantiate their findings, the researchers conducted experiments involving corn plants grown in two types of soil: one without arsenic and the other with high levels of arsenic. They also grew corn plants deficient in benzoxazinoid production due to a genetic defect for comparison. The results were conclusive, showing that benzoxazinoid-producing corn exhibited better growth in arsenic-contaminated soil and accumulated significantly less arsenic in their biomass compared to plants lacking benzoxazinoids. Furthermore, when benzoxazinoids were added to the arsenic-containing soil, even the mutant plants were protected from arsenic toxicity, highlighting the role of these compounds in reducing arsenic uptake by plants.

The researchers delved deeper to uncover the underlying mechanism behind the protective effect of benzoxazinoids. While analyses of the root microbiome ruled out the involvement of bacteria and fungi, chemical analyses of the soil revealed that a particularly toxic form of arsenic diminished in the presence of benzoxazinoids. This suggests that benzoxazinoids transform arsenic in a way that prevents its uptake through the roots, though the exact chemical processes involved are still under investigation.

Long-Term Benefits and Future Applications

Further experiments demonstrated that the positive impact of benzoxazinoids in the soil persisted over time, with even the second generation of corn plants benefiting from the benzoxazinoids released by the first generation. This long-lasting effect opens up possibilities for utilizing this knowledge in practical applications, such as cultivating plant varieties with enhanced benzoxazinoid production in arsenic-contaminated areas. By developing hyper-emitting plants through traditional breeding methods or targeted genetic modifications, it may be possible to limit the entry of arsenic into the food chain, thereby safeguarding human health.

Professor Schlaeppi emphasizes the potential of these findings for addressing arsenic contamination issues, highlighting the importance of exploring strategies to leverage benzoxazinoids to mitigate arsenic toxicity in agricultural settings. By understanding and harnessing the natural defense mechanisms of plants like corn, researchers aim to develop sustainable solutions for managing arsenic contamination and ensuring food safety.

Implications for Agriculture and Environmental Sustainability

The discovery of corn’s ability to reduce arsenic toxicity in soil through benzoxazinoids not only offers insights into plant defense mechanisms but also holds significant implications for agriculture and environmental sustainability. By elucidating the role of specific plant compounds in mitigating arsenic uptake, this research provides a foundation for developing innovative strategies to address arsenic contamination in agricultural soils.

Moving forward, researchers and agricultural practitioners can explore the feasibility of incorporating benzoxazinoid-producing crops in arsenic-affected regions to reduce the health risks associated with arsenic exposure through food consumption. Moreover, the potential for enhancing benzoxazinoid production in crops through breeding or genetic engineering presents a promising avenue for improving crop resilience to arsenic contamination.

The discovery of corn’s protective mechanism against arsenic toxicity underscores the importance of understanding plant-soil interactions in mitigating environmental pollutants and safeguarding human health. By harnessing the natural capabilities of plants like corn, we can take significant strides towards sustainable agriculture practices and environmental stewardship, ultimately creating a safer and healthier food supply for future generations.

Links to additional Resources:

1. Nature.com 2. ScienceDirect.com 3. EurekAlert.org

Related Wikipedia Articles

Topics: Corn (plant), Arsenic (element), Benzoxazinoids (compound)

Corn smut
Corn smut is a plant disease caused by the pathogenic fungus Ustilago maydis. One of several cereal crop pathogens called smut, the fungus forms galls on all above-ground parts of corn species such as maize and teosinte. The infected corn is edible; in Mexico, it is considered a delicacy, called...
Read more: Corn smut

Arsenic
Arsenic is a chemical element; it has symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a notoriously toxic metalloid. It has various allotropes, but only the grey form, which has a...
Read more: Arsenic

Bx1 benzoxazin1
Function Maize gene for first step in biosynthesis of benzoxazin, which aids in resistance to insect pests, pathogenic fungi and bacteria. First report Hamilton 1964, as a mutant sensitive to the herbicide atrazine, and lacking benzoxazinoids (less than 1% of non-mutant plants). Molecular characterization reveals that the BX1 protein is...
Read more: Bx1 benzoxazin1

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