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United States Department of Agriculture

Agricultural Research Service

Title: Identification and Effects of Maize Silk Volatiles on Cultures of Aspergillus Flavus

Author
item Zeringue Jr, Hampden

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 24, 1999
Publication Date: N/A

Interpretive Summary: Aflatoxins are highly toxic compounds produced by the mold Aspergillus flavus. Infection of corn, destined to be utilized in food or feed, with Aspergillus flavus and subsequent aflatoxin contamination reduces both the quality and economic value of the crop and is a potential health problem to both man and animal. In simple Petri plate bioassays it was observed that volatiles emitted from silks from different corn varieties had a profound effect on the growth of the fungus and, consequently, aflatoxin production. It was found that the silks of aflatoxin field resistant corn varieties exhibited a larger relative concentration of volatile anti-fungal compounds compared to silk volatiles of susceptible varieties tested. This observation may relate to a regulated defense mechanism for protecting the developing corn kernel from fungal attack. This information would be beneficial to plant breeders and molecular biologists who are looking for disease and aflatoxin resistant traits to decrease the incident of aflatoxin contaminated corn.

Technical Abstract: Volatiles generated from cornsilks of individual genotypes of maize were found to exhibit differences in biological activities when the volatiles were exposed to 5-day solid cultures of Aspergillus flavus. In inverted potato-dextrose-agar Petri plate bioassays, it was found that volatiles emitted from silks from the different maize genotypes had a profound effect on the growth of the fungus and, consequently, aflatoxin production. In order to determine the underlying cause for this bioactivity, volatiles emitted from the maize silks were trapped on Tenax glass columns and were analyzed by GC/MS. Aflatoxin-field resistant maize genotypes exhibited a larger relative concentration of the antifungal aldehyde, furfural (2-furancarboxaldehyde), when compared to the relative concentrations of the field susceptible varieties tested. In a closed container 5-day study, it was observed that fresh 1-day-old and 4-day-old cornsilk samples of aflatoxin resistant maize genotypes emitted higher concentrations of furfural compared to those from susceptible genotypes. This observation probably explains the reason of the bioactivity observed in the in vitro bioassays and its presence appears to contribute to a defense mechanism for protecting the developing maize kernel from fungal attack.

Last Modified: 10/1/2014
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