Distribution and genetic diversity among Aspergillus flavus isolates across three agro-ecologies essential for maize cultivation in Ghana

Authors: DADZIE, M. - University Of Ghana; OPPONG, A. - Crop Research Institute - Ghana; OFORI, K. - University Of Ghana; ELEBLU, J. - University Of Ghana; BEATRICE, E. - University Of Ghana; BLAY, E. - University Of Ghana; OBENG-BIO, E. - University Of Ghana; APPIAH-KUBI, Z. - Crop Research Institute - Ghana; Warburton, Marilyn

Submitted to: Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/25/2019
Publication Date: 7/11/2019
Citation: Dadzie, M.A., Oppong, A., Ofori, K., Eleblu, J., Beatrice, E., Blay, E., Obeng-Bio, E., Appiah-Kubi, Z., Warburton, M.L. 2019. Distribution and genetic diversity among Aspergillus flavus isolates across three agro-ecologies essential for maize cultivation in Ghana. Plant Pathology. 68(8):1565–1576. https://doi.org/10.1111/ppa.13067.
DOI: https://doi.org/10.1111/ppa.13067

Interpretive Summary: Fungal mycotoxins are important contaminants of agricultural commodities that pose serious concerns to producers, consumers and exporters. Aflatoxin is a carcinogenic metabolite produced by the fungi Aspergillus flavus and A. parasiticus. A. flavus and other mold species living in the soil contaminates several crops including maize where consumption of the toxin causes enormous health and socioeconomic costs to humans. The identification of local A. flavus strains that do not make the toxin is a necessary step in the creation of a biocontrol product that stops the infection of A. flavus in farmer’s fields. This study looked at what fungi, and in particular, what strains of A. flavus were present in different fields in all growing areas of Ghana; whether they made aflatoxin; and whether soil conditions would increase the density of A. flavus populations or not. While several non-toxin producing strains were found, soil properties were not found to influence how much fungus was present in the field.

Technical Abstract: Fungal mycotoxins are important contaminants of agricultural commodities that pose serious concerns to producers, consumers and exporters. Aflatoxin is a carcinogenic metabolite produced by the fungi Aspergillus flavus and A. parasiticus. The toxin causes enormous health and socioeconomic costs to human society. Aspergillus flavus and other mould species living in the soil contaminates several crops including maize. This study was undertaken with the objectives to: (1) assess the presence of A. flavus and other mould in Ghanaian soil; (2) determine the distribution and density of A. flavus under three agro-ecologies noted for major maize production; and (3) assess the effect of % carbon (C), % nitrogen (N) and soil pH on A. flavus population densities and diversity in the isolates found across the agro-ecologies. The data showed seven moulds that were common across the agro-ecologies. Significant differences (p < 0.05) were observed in the A. flavus density and distribution within and across these agro-ecologies. Fumesua soils recorded the highest levels of A. flavus (1.185 x 103 cfu/g) while Akomadan recorded the least (9.76 x 102 cfu/g). Percentage available C, N and soil pH did not significantly influence A. flavus density. The A. flavus isolates identified in this study varied in genetic sequence within the aflatoxin gene cluster, but these differences were not distinguishable by origin.