Fungal volatile organic compounds: new tools to reduce mycotoxin contamination in crops?

The fungi Aspergillus flavus and Fusarium verticillioides can co-occur in maize and produce the mycotoxins aflatoxins and fumonisins, respectively. Both mycotoxins can adversely affect the health of humans and animals, although the mode of action of the toxins differ.
To better understand the interaction of the fungi, we examined the effects of production of volatile organic compounds (VOCs) by each species on mycotoxin production in the other. We reported the VOCs emitted by F. verticillioides by examining a wild-type strain of F.
verticillioides and its mutant strains in which a fumonisin biosynthetic gene (FUM1 or FUM6) was deleted. Both mutants emitted specific VOCs compared to wild-type and ethyl 3-methylbutanoate, emitted by both mutants, reduced fumonisin production of wild strain.
In addition, we observed inter-species interactions between A. flavus and F. verticillioides.
Fungal strains were grown under two conditions: a non-physical contact condition in which two strains shared the same atmosphere but not the same substrate; and a physical contact condition in which two strains shared atmosphere and substrate. During interactions of the two fungal species, fumonisins and aflatoxins were detected in the substrate, and a significant increase in levels of both mycotoxins occurred.
Together, these results provide evidence that VOCs emitted by toxigenic fungi can increase
the mycotoxins produced by other species likely caused by competition mechanism activated by the VOCs. On the other hand, these results show evidence that selected VOCs can be used for potential and novel VOC-based biocontrol strategies.