Crop Host Influences on Outcomes of Competition Between Aspergillus Section Flavi Species Coinfecting Maize and Groundnuts

Abstract

Aspergillus section Flavi species co-occur and contaminate crops, including maize and groundnuts, with aflatoxins. Competition among A. flavus genotypes is influenced by crop host, but competition between Aspergillus species has not been examined. The objectives of the current study were to (i) assess competition among four aflatoxin-producing species on maize and groundnuts and (ii) evaluate within-species variation in competitive ability during coinfection with another species on the two crops. For the first objective, maize and groundnut kernels were coinoculated with all possible pairs of A. flavus, A. parasiticus, A. aflatoxiformans, and an unnamed taxon known as the Lethal Aflatoxicosis Fungus (LAF). For the second objective, three isolates from each of the four species were coinoculated with a representative isolate of a competing species on the two hosts. In all experiments, isolates were cocultured for 7 days at 30°C, and then aflatoxins and total conidia were measured, and the percentages of each species within a treatment were assessed with quantitative pyrosequencing. Maize kernels supported greater aflatoxin production than groundnuts, whereas groundnuts supported greater sporulation than maize. Hosts differentially influenced competition between species, with A. flavus generally more competitive on maize and LAF more competitive on groundnuts. Overall, A. flavus and LAF were the most competitive species, whereas A. parasiticus was the least competitive. However, isolates within a species varied in competitive ability and in their response to host and competing species. Results suggest that although crop hosts influence Aspergillus community composition, within-species variability makes it difficult to predict outcomes of competition on a particular crop. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .