Submitted to: Open Mycology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2009
Publication Date: 5/25/2009
Citation: Duran, R.M., Cary, J.W., Calvo, A.M. 2009. The role of veA on Aspergillus flavus infection of peanuts, corn and cotton. Open Mycology Journal. 3:27-36 Interpretive Summary: This work describes experiments that have been conducted in an effort to better understand the mechanisms by which fungi invade crops and produce aflatoxins. Aflatoxins are toxic and carcinogenic compounds often produced by the fungi, Aspergillus flavus and Aspergillus parasiticus, during growth on crops such as corn, peanuts, cottonseed, and treenuts. Because of the potential health risks, aflatoxin contamination of food and feed crops is also of great economic importance to farmers who cannot sell their crops due to strict domestic and international regulatory guidelines with regards to aflatoxin contamination. This study looked at the ability of a strain of A. flavus that carried a non-functional, mutated version of the veA gene to invade and spread in peanut, corn, and cottonseed. The non-mutated version of the veA gene is known to be required for aflatoxin production but we did not know if it played a role in the ability of the fungus to invade plant tissues. We found that an A. flavus strain carrying the mutated veA gene did not invade and spread in plant tissues as well as the strain carrying a functional veA gene. This work further emphasizes the importance of the veA gene as a target in strategies for eliminating fungal growth and aflatoxin contamination of food and feed crops.
Technical 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 poses serious negative economic and health impacts in both humans and domestic animals. It is; therefore, of a great importance to determine ways to control A. flavus dissemination, survivability and toxin formation. In this study, we demonstrated 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 peanuts 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.