The Role of veA in Aspergillus flavus Infection of Peanut, Corn and Cotton

Abstract

The aflatoxin-producing fungus Aspergillus flavus is a causal agent of preharvest contamination of food commodities such as oil seed crops worldwide. Peanut, corn and cottonseed are among the oil seeds that are susceptible to aflatoxin contamination during invasion of these crops by A. flavus. Contamination of agricultural commodities with aflatoxins can result in serious economic hardships to producers and adverse health impacts in both humans and domestic animals. It is therefore of great importance to determine ways to control A. flavus dissemination, survival and toxin formation. In this study we demonstrate the role of the veA regulatory gene in the contamination of peanut, corn and cotton by A. flavus. Virulence of A. flavus on peanut and corn seeds was reduced in the absence of the veA gene product. Generation of air-borne asexual spores was reduced and production of aflatoxin and sclerotia in peanut seeds, viable or non-viable, or in viable corn seed was completely blocked when infected with the A. flavus veA mutant (veA). In planta inoculation of cotton bolls also showed that conidiation was decreased in bolls inoculated with the veA strain and spread of the veA strain to seed in locules adjacent to the inoculated locule was less than observed with the wild-type veA strain. As observed in peanut and corn, no aflatoxin was produced in seed harvested from cotton bolls inoculated with the veA strain while aflatoxin was present in seed from wild-type veA inoculated bolls.