Will climate change increase the risk of a toxin in U.S. corn?
Climate Change food security Aflatoxin

Will climate change increase the risk of a toxin in U.S. corn?

Dr. Lindy Whitehouse
Dr. Lindy Whitehouse

In 10 seconds? Researchers predict that over 89.5% of corn-growing counties across 15 US states will be affected by aflatoxin contamination between 2031 and 2040. The findings from their study could have worrying implications for global food security.

What’s the discovery? Aflatoxin is a toxic compound that is produced by the fungi Aspergillus flavus and Aspergillus parasiticus. This toxin can infect several crops and can cause serious health issues if ingested by humans or animals including dairy cows, sheep, and goats. While aflatoxin infections are common in the United States, contamination in the areas that make up the corn belt has rarely been seen. However, this could be set to change. Using various climate models, researchers have found that aflatoxin is going to become more of a problem in the American Corn Belt which could have a devastating impact on global food security.

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Why will climate change increase aflatoxin contamination? Increasing temperatures will cause many of the states in the Corn Belt to suffer hotter and dryer conditions than they have historically experienced. Hot and dry weather are optimal conditions for these fungi to release their spores and once airborne, the chances that they will contaminate crops increase. The changes in weather patterns can also cause stress to the plants, making them more vulnerable to infection. One way that farmers can reduce the vulnerability of their crops to fungal infection is by keeping them irrigated. Why? Because water prevents plants from getting stressed. However, with climate change in these areas predicted to cause rain to fall more heavily but less frequently, it is likely that periodic water scarcity will further exacerbate the problem.

How did the researchers arrive at these results? The study used a model to predict aflatoxin risk based on corn plant growth stages and weather to determine which US regions were most likely to be at high risk from aflatoxin infection between 2031 and 2040. This model took into consideration changes in planting time as a result of shifts in the weather patterns, as well as how changes in the weather could impact different growth stages of the crop. The researchers used daily maximum and minimum temperature and precipitation data from 16 climate change models to project aflatoxin risk during the timeframe.

Number of aflatoxin-related insurance claims by county in 16 selected corn-planting states. Source: Yu, Hennessy and Wu, 2020.
Number of aflatoxin-related insurance claims by county in 16 selected corn-planting states: 2001–2016. White portions in the sixteen states area were excluded from analysis because data on corn plantings were missing over some or all of the study period. Source: Yu, Hennessy and Wu, 2020.

What impact could this have on corn production? Increases in fungal infections in the corn belt will impact food sources and the livelihoods of the farmers that depend on them. The US is the largest exporter of field corn, and it is consumed in products such as corn chips, cornflakes, and corn tortillas as well as being used for animal feed and ethanol production. This particular toxin can result in significant economic losses, amounting from US$52.1 to US$1.68 billion annually for just the US corn industry. On a wider scale, increases in fungal infections as a result of climate change will have a devastating impact on global food security. Changing weather patterns and temperatures will cause a shift in the range of pathogens and pests which will expose crops to new diseases, potentially impacting yield. However, there are some limitations to this study that need to be taken into consideration. For example, changes in how the farmers grow their crops and the development of new technologies could better aflatoxin control in the future. The model also doesn’t take into consideration increasing carbon dioxide levels which could impact aflatoxin production.

Can we prevent it? Some strategies can be used to help reduce aflatoxin risk. As previously mentioned, plants are particularly susceptible to infections when they are stressed. Irrigation can help reduce drought-related stress which could prevent the crops from becoming infected. Conventional breeding methods have been used to develop crops that can withstand both drought and fungal infection and, scientists have also developed biotechnologies such as biocontrol, transgenic or gene-edited corn, and RNA interference (RNAi) corn. These technologies can help prevent the fungi from producing aflatoxin which prevents the crops from becoming damaged.

Did you know? Plants experience stress just like people …

In fact, plants are constantly stressed as a result of several different abiotic and biotic factors. As plants can’t run away from stress, they need to adapt to it. To do this they must alter their chemistry which requires the uptake of nutrients that are key to these chemical processes.

One important nutrient that helps plants to fight stress is potassium. For example, potassium helps improve water uptake, strengthens the cell walls, and enhances damage repair.

Plants can also grow their roots in search of water or other nutrients, and the root systems architecture plays a central role in the plant’s response to stress.

Recently, researchers identified a master gene that modulates a plant’s response to both abiotic and biotic factors. SDA1 is a tiny but critical gene that has been shown to regulate other genes which in turn influences the biotic and abiotic response of a plant to stress.

Lindy has distilled 10 research papers, saving you 33 hours of reading time.

The Science Integrity Check of this 3-min Science Digest was performed by Dr. ASM Mainul Hasan.

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