|Zeringue Jr, Hampden|
Submitted to: Canadian Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 13, 1998
Publication Date: N/A
Interpretive Summary: Aflatoxins are highly toxic compounds produced by the mold Aspergillus flavus. Infection of cottonseed with Aspergillus flavus and subsequent aflatoxin contamination reduces both the quality and economic value of the crop and is a potential health problem. The effects on aflatoxin production in mature cottonseeds were examined after the developing cotton bolls had been pretreated with a mold extract. It was discovered that aflatoxin formation could be inhibited by using this pretreatment procedure. This information will be beneficial to the scientific community (phytopathologists, plant physiologists, mycologists) who are studying the defensive mechanisms in the cotton plant and the relationship to aflatoxin formation. The information obtained in this study will ultimately lead to decrease aflatoxin contamination of pre- and post-harvest cottonseed.
Technical Abstract: Artificially wounded 22 to 27-day old developing cotton bolls were inoculated with a cell-free, hot water-soluble mycelial extract of an atoxigenic strain of A. flavus. On the same day or after 1, 2, 5, and 8 days following the initial inoculation, a second artificial wound was produced adjacent to the first wound and a spore suspension of a toxigenic strain of A. flavus was inoculated into the second wound. At boll maturity, the cotton seeds located within the locules underlying the areas that were inoculated with the fungal extract and infected with the toxigenic A. flavus strain were found to contain the following percentages of aflatoxin B1 inhibition: bolls inoculated on the same day exhibited 2.5% inhibition, 19.1% on 1-day bolls, 42.3% on 2-day bolls, 97.3% on 5-day bolls and 36.3% on 8-day bolls. In a separate experiment, no significant difference in aflatoxin concentration was found when developing cotton bolls were pretreated with either cell-free hot water soluble extracts of toxigenic strains of A. flavus or with cell-free, hot water-soluble extracts of atoxigenic strains of A. flavus. There were slight differences in aflatoxin B1 inhibitions in the 5-day boll pretreatment when mycelial extracts from different atoxigenic strains were compared (82.4% to 97.4%) followed with the inoculation of a spore suspension of the same toxigenic strain. These results suggest a possible host defense mechanism that may be triggered by the cell-free mycelial extract.