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article imageEssential Science: Saving the crops — tackling fungal disease

By Tim Sandle     Feb 8, 2021 in Science
Cereals are a stable foodstuff around the world, yet the crops can be ruined by fungal diseases and this can lead to world hunger. Different studies are being conducted to tackle mycotoxins, and three examples are considered.
Mycotoxins are toxic metabolites produced by some fungi. These toxins, which differ in terms of potency and degree of harm between different species of fungi, are capable of causing disease. The primary concern, in terms of incidences and global reach, is with the toxic chemical products produced by fungi that readily colonize crops. High levels of mycotoxins mean that the crops may not be fit for human consumption, and many regulatory agencies specify maximal permitted levels.
Of particular concern to human health are harmful mycotoxins that possess acute toxicity, causing damage to liver, kidneys, nervous system, skin, mucous membranes, immune systems. In some cases, chronic toxicity may provoke cancer, may cause congenital abnormalities and malformations in the embryo.
These cultured Fusarium species are commonly found in home  business and public bathroom sink drains...
These cultured Fusarium species are commonly found in home, business and public bathroom sink drains, according to Penn State University researchers.
Penn State Department of Public Information
This week’s Essential Science looks at three strategies designed to reduce mycotoxin levels in relation to cereals intended as food.
Fusarium Head Blight
Researchers from the U.S. Department of Agriculture - Agricultural Research Service have located a gene that can be used to develop varieties of wheat. This gene could make wheat more resistant to fungal disease, a disease that can seriously impact on wheat supply.
A healthy wheat head (left) stands in contrast to one inoculated with Fusarium graminearum  which sh...
A healthy wheat head (left) stands in contrast to one inoculated with Fusarium graminearum, which shows severe symptoms of scab.
USDA
The disease of concern is Fusarium Head Blight. The disease is also known as ‘scab’. Other types of cereals impacted include barley, oats, rye, and corn. The causative agent, the fungus Fusarium produce mycotoxins in cereal crops and these can affect human health. The mycotoxins are fumonisins and trichothecenes.
It also stands that fungal toxins can build up in enclosed spaces, especially where there is poor air distribution.
Burned wheat in a field near Magdeburg. Farmers say that when dry wheat burns like straw
Burned wheat in a field near Magdeburg. Farmers say that when dry wheat burns like straw
Tobias SCHWARZ, AFP
The gene was identified in Thinopyrum wheatgrass. If this gene is genetically transferred, studies suggest the gene effectively reduces Fusarium Head Blight by detoxifying the mycotoxins secreted by the fungus. The gene also provides protection to diseases like crown rot, which is a wheat disease caused by another fungus.
The potential application of the gene is described in a paper published in the journal Science. The paper is titled “Horizontal gene transfer of Fhb7 from fungus underlies Fusarium head blight resistance in wheat.”
Fungal mating
A different fungus Aspergillus flavus can also infect several crops, such as corn. Some types of A. flavus produce a specific mycotoxin called aflatoxin. One measure undertaken in the agricultural sector is to use a non-mycotoxin producing strain of A. flavus, as a biocontrol strains to out-compete the mycotoxin producing strains.
Ophidiomyces ophiodiicola from Hoplocephalus bungaroides  the broad-headed snake. It is a venomous s...
Ophidiomyces ophiodiicola from Hoplocephalus bungaroides, the broad-headed snake. It is a venomous snake that is restricted to the Sydney Basin in NSW, Australia. (09/01/2010)
Sigler L, Gibas C (CC BY-SA 4.0)
A different approach is being considered. This involves using native strains of the fungus that do not produce mycotoxins as opposed to farmers buying commercial strains. This is because native strains have been found to be more effective than commercial strains, based on fungal biology. Here native strains are compatible, enabling them to reproduce and sustain their population. This decreases the need for farmers to repopulate stocks.
The novel approach has been outlined in the Agronomy Journal, where the paper is titled “Trial Summary on the Comparison of Various Non-Aflatoxigenic Strains of on Mycotoxin Levels and Yield in Maize.”
Computer models to predict success
Mycotoxins can be detected in corn through testing. However, predicting the conditions that cause fungi to produce the carcinogens is challenging. A new computer program sets out to address this.
Aspergillus fumigatus is a fungus of the genus Aspergillus  and is one of the most common Aspergillu...
Aspergillus fumigatus is a fungus of the genus Aspergillus, and is one of the most common Aspergillus species to cause disease in individuals with an immunodeficiency.
US Department of Health and Human Services
The program, which looks at corn stores, has been developed at the U.S. ARS National Center for Agricultural Utilization Research. The software makes use of equations to mathematically predict mycotoxin levels. The factors that need to be inputted include temperature, soil type, numbers of insects and other factors that influence the growth of fungi and who the fungus might spread.
Lurking in your salt
In related news, researchers have established concerns relating to commercial salts. A science team extracted living fungi from seven salt samples. The fungi discovered in the salt can spoil food when used as an ingredient. The salt can also introduce mycotoxins when consumed.
Salt farmers harvesting salt  Pak Thale  Ban Laem  Phetchaburi  Thailand.
Salt farmers harvesting salt, Pak Thale, Ban Laem, Phetchaburi, Thailand.
JJ Harrison (CC BY-SA 3.0)
The typical levels of fungi are 1.7 spores per gram, this presents a particular risk to industrially to make cured meats, fermented pickles and brined cheeses.
Essential Science
This article forms part of Digital Journal’s long-running Essential Science series, where new research items relating to wider science stories of interest are presented by Dr. Tim Sandle on a weekly basis.
WHO-recommended limits for air pollution are broken in 99 per cent of London
WHO-recommended limits for air pollution are broken in 99 per cent of London
Niklas HALLE'N, AFP/File
Last week, we considered how economic development, fossil-fuel combustion and air quality are connected on both international and national scales. This led to a review of national and international solutions to tackle climate change.
The week before, we learned that the European Union has taken a major step, whatever your individual feelings, in declaring mealworms as ‘safe to eat’ and hence as a sustainable source of protein that can be used to replace meat within a diet.
More about Crops, Cereal, Fungi, mycotoxins
 
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