Special Issue "Current Status and Challenges of Aflatoxin Biocontrol Strategies"

A special issue of Toxins (ISSN 2072-6651). This special issue belongs to the section "Mycotoxins".

Deadline for manuscript submissions: 31 March 2022.

Special Issue Editors

Dr. Geromy G. Moore
E-Mail Website
Guest Editor
USDA Agricultural Research Service, Southern Regional Research Center, New Orleans, Louisiana, USA
Dr. Hillary L. Mehl
E-Mail Website
Guest Editor
USDA Agricultural Research Service, Pest Management and Biocontrol Research, Maricopa, Arizona, USA
Dr. Kenneth A. Callicott
E-Mail Website
Guest Editor
USDA Agricultural Research Service, Pest Management and Biocontrol Research, Maricopa, Arizona, USA

Special Issue Information

Dear Colleagues,

Aflatoxin contamination of agricultural commodities is a global issue with potentially significant economic and health impacts. There are disparities between countries with regard to the impact of, and approach to, the aflatoxin problem, with Low to Middle Income Countries (LMICs) experiencing more of the detrimental effects of aflatoxin contamination. Research to prevent infection by aflatoxin producing fungi, mitigate the negative effects associated with aflatoxin contamination, and develop resistant or defensible plant hosts offers opportunities to ensure a safe food and feed supply. The implementation of biological control strategies (either direct or indirect) are preferred and continue to be explored, especially over use of potentially harmful chemical fungicides. However, research is still needed to develop effective, affordable biocontrol products and strategies to for target crops and regions worldwide where aflatoxin contamination events are frequent and severe. Furthermore, the benefits of combining aflatoxin biocontrol with other aflatoxin and general crop management tactics needs to be explored. Therefore, the goal of this Special Issue is to showcase the many different avenues of research that relate to sustainable pre-harvest or post-harvest biological control of aflatoxin producing fungi.

Dr. Geromy G. Moore
Dr. Hillary L. Mehl
Dr. Kenneth A. Callicott
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a double-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Toxins is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Aspergillus section Flavi
  • mechanisms of biocontrol
  • pre-harvest
  • post-harvest
  • induced host
  • resistance
  • stability
  • climatic impacts
  • fungal diversity
  • biopesticides
  • food or feed crops

Published Papers

This special issue is now open for submission, see below for planned papers.

Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Fungal Chemistry as A Mechanism of Aflatoxin Biocontrol: A Tale of Three VOCs
Authors: Geromy G. Moore, Matthew D. Lebar, Carol H. Carter-Wientjes
Affiliation: Southern Regional Research Center, USDA-ARS, New Orleans, LA, USA
Abstract: The use of non-aflatoxigenic A. flavus as biocontrol agents, to prevent aflatoxin contamination of agricultural commodities, is an effective pre-harvest strategy that is being implemented all over the world. These strains exhibit growth characteristics that indicate their mechanism of action involves aggressive colonization, thereby outcompeting native aflatoxin producing strains in the field. However, there may be additional mechanisms involved that enhance the competitive advantage for A. flavus biocontrol. One novel mechanism that is only recently being explored involves the production of metabolites that inhibit the production of one or more Aspergillus mycotoxins, such as aflatoxin and/or cyclopiazonic acid (CPA). Not only could secreted metabolites that inhibit mycotoxin production offer selectable markers for future biocontrol strains, these compounds could be helpful as post-harvest treatments to prevent storage-related issues with aflatoxin contamination. In a previous study, we looked at ten volatile organic compounds and found three of them (reportedly unique to non-aflatoxigenic A. flavus) were able to greatly reduce aflatoxin production, with two of them also completely inhibiting CPA production in at least one of the three aflatoxigenic strains tested. In this study, we explored the potential for a cumulative effect on production of aflatoxin and CPA by various combinations of those three most-inhibitive non-aflatoxigenic VOCs (2,3-dihydrofuran, 3-octanone and decane). We also looked at other mycotoxins readily produced by aflatoxigenic species. Here we will share our findings.

Title: Genetic responses and aflatoxin inhibition during interaction between aflatoxigenic and non-aflatoxigenic Aspergillus flavus
Authors: Rebecca R Sweany; Brian M Mack; Geromy G Moore; Matthew K Gilbert; Jeffrey W Cary; Kanniah Rajasekaran; Kenneth E Damann Jr
Affiliation: United States Department of Agriculture
Abstract: Aflatoxin is a carcinogenic mycotoxin produced by Aspergillus flavus in corn. Non-aflatoxigenic A. flavus isolates are applied to corn fields as a biocontrol to reduce aflatoxin contamination. Direct contact or touch between aflatoxigenic and non-aflatoxigenic isolates dramatically reduces aflatoxin production. To understand the mechanism of touch inhibition, a high-throughput RNA-seq study was conducted to examine gene expression during their interaction. Non-aflatoxigenic strain KD17 and aflatoxigenic strain KD53 were grown separately and in co-culture for 30 and 72 h. Toxin production was high in the aflatoxigenic monoculture and negligible in co-cultures. When grown separately, the toxigenic strain represented 7% and 33% of the combined biomass at 30 and 72 h, respectively. However, only 3% of the sequence reads uniquely aligned to the aflatoxigenic strain during co-culture, indicating growth and/or gene expression of the aflatoxigenic strain was inhibited in response to the non-aflatoxigenic strain. Few reads aligned to the aflatoxin gene cluster during co-culture. Eighteen genes expressed during mono-culture of the non-aflatoxigenic strain were further up-regulated during co-culture, indicating a response to contact. Of those genes, seven belong to a putative secondary metabolite cluster, suggesting a potentially inhibitory compound is produced. Taken together, these results suggest that non-aflatoxigenic strains inhibit growth and aflatoxin biosynthetic gene cluster expression in aflatoxin-producing strains. In addition, other secondary metabolite genes are upregulated during biocontrol interaction. This study demonstrates a potential role of inhibitory secondary metabolites in the biocontrol mechanism and deserves further exploration to improve biocontrol formulations.

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