France
August 18, 2011

Cereals can be contaminated by mycotoxins that are synthesised by microscopic fungi. These mycotoxins can cause poisoning in both animals and humans. In Europe, the risk is mainly linked to mycotoxins produced in the field before harvest, by fungi of the Fusarium genus. INRA researchers have shown that certain phenolic compounds (such as ferulic acid), which are abundant in wheat bran and also present in other cereals, are able to inhibit the synthesis of mycotoxins by these toxinogenic fungi.

Several species of fungi of the genus Fusarium may be present on cereal ears. These infections often cause yield losses, but it is the fact that they produce mycotoxins that poses problems.

These mycotoxins are particularly heat-stable, and no sufficiently efficient decontamination process exists at present. Strategies to control the risks of contamination must therefore target preventive action before harvest.

Only some types of Fusarium produce toxins (type B trichothecenes, zearalenone and fumonisines), and this production also varies as a function of environmental conditions. Through the defence reactions it develops, the physiological status at the time of infection and the biochemical composition, the host plant (wheat, barley, maize, etc.) exerts considerable influence on the amounts of type B trichothecenes that accumulate.

Substances that are able to block mycotoxin synthesis

The INRA researchers thus focused on the factors present in grains that might exert a modulating effect on the synthesis of TCTB when the fungus colonises the plant. They thus identified several substances from wheat bran capable of inhibiting the accumulation of mycotoxins. After purification and structural analysis of the biochemical entities that could interfere in mycotoxin biosynthesis, the team showed that these were mainly ferulic acid and a phenolic dimer derived from ferulic acid.

The scientists then demonstrated in vitro that ferulic acid inhibited TCTB production very effectively at concentrations close to those observed in cereal grains.

The next step of this research was to demonstrate that ferulic acid reduced the expression of Tri genes coding for the synthesis of enzymes involved in trichothecene biosynthesis. It appears that this reduction in the expression of Tri genes results directly from the antioxidant potential of ferulic acid. The precise mechanism governing this regulation is currently under investigation.

The research under way at present aims to test these original findings under real conditions. In particular, it is necessary to analyse the levels of ferulic acid present in the grains of different crops and link these levels with the susceptibility of different varieties to mycotoxin contamination. The selection of cereal varieties that accumulate high levels of ferulic acid, or antioxidant compounds with analogous effects, during the early stages of grain filling is one of the options that will be explored in order to reduce the production of mycotoxins in the field. The inclusion of these natural antioxidant compounds in "biofungicide" formulations is also under study.

Website: https://www.inrae.fr

Published: August 18, 2011