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Production of cyclopiazonic acid, aflatrem, and aflatoxin by Aspergillus flavus is regulated by veA, a gene necessary for sclerotial formation

Abstract

The plant pathogenic fungus Aspergillus flavus produces several types of mycotoxins. The most well known are the carcinogenic compounds called aflatoxins. In addition, A. flavus produces cyclopiazonic acid and aflatrem mycotoxins, contributing to the toxicity of A. flavus infected crops. Cyclopiazonic acid is a specific inhibitor of calcium-dependent ATPase in the sarcoplasmic reticulum that results in altered cellular Ca++ levels. Aflatrem is a potent tremorgenic mycotoxin known to lead to neurological disorders. Previously we showed that a gene called veA controls aflatoxin and sclerotial production in A. parasiticus. In this study in A. flavus, we show that the veA homolog in A. flavus not only is necessary for the production of aflatoxins B1 and B2 and sclerotia, but also regulates the synthesis of the mycotoxins cyclopiazonic acid and aflatrem. The A. flavus ΔveA mutant was completely blocked in the production of aflatrem and showed greater than twofold decrease in cyclopiazonic acid production. The genes involved in the synthesis of cyclopiazonic acid are unknown; however, the aflatrem gene cluster has been characterized. Northern hybridization analysis showed that veA is required for expression of the A. flavus aflatrem genes atmC, atmG, and atmM. This is the first report of a regulatory gene governing the production of cyclopiazonic acid and aflatrem mycotoxins.

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Acknowledgements

A.M.C. and J.W.C. thank Jan Tkacz and Mike Goetz from Merck Co. for providing the aflatrem standard. A.M.C. gratefully acknowledges John Mitchell for his suggestions for the chemical analysis and Barry Scott for his useful comments on aflatrem-inducing cultures. J.W.C. gratefully acknowledges Pam Harris and Jolie Bonanno for their technical support.

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Correspondence to Ana M. Calvo.

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Duran, R.M., Cary, J.W. & Calvo, A.M. Production of cyclopiazonic acid, aflatrem, and aflatoxin by Aspergillus flavus is regulated by veA, a gene necessary for sclerotial formation. Appl Microbiol Biotechnol 73, 1158–1168 (2007). https://doi.org/10.1007/s00253-006-0581-5

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Keywords

  • Aspergillus flavus
  • Cyclopiazonic acid
  • Aflatrem
  • Aflatoxin
  • Sclerotia
  • Mycotoxin regulation