The Key Largo Hypothesis Recent Advances in Understanding Aflatoxin Contamination in Peanut with Omics and Biotechnology

Aflatoxin contamination continues to be a perennial issue resulting in significant economic losses to the peanut industry globally. It also poses a serious risk to human and animal health, making it a major focus of research into novel mitigation strategies. Over the last 63 years, much has been learned about the production and regulation of aflatoxin in Aspergillus fungi and the interactions of these organisms with host plants like maize and peanut, though there are many fundamental questions about the nature and purpose of aflatoxin production that remain unanswered. Aflatoxin contamination has been consistently connected to the occurrence of drought and heat stresses, which are of growing concern with ongoing climate change. The cause of this association has, however, remained elusive. Based on the observation that antioxidant mechanisms are consistently featured among host plant responses to both drought and heat stress and Aspergillus infection, we began an investigation into the potential role of reactive oxygen species (ROS) in drought-A. flavus interactions, the role of ROS in aflatoxin production regulation, how ROS may function in signaling between host plants and A. flavus during infections under drought conditions, and their effects on aflatoxin contamination. We also investigated the fundamental differences between isolates of A. flavus in aflatoxin production capability and how these may be linked to antioxidant protection for the fungus. Here, we review the history and current status of our ongoing research into the role of ROS in aflatoxin production using biotechnology and various omics technologies, including transcriptomics, proteomics, metabolomics, and comparative genomics. Resources and knowledge generated by these studies can inform future research directions into peanut-A. flavus interactions, evolution and gene functional studies in A. flavus, and the development and selection of new genetic and biological markers for plant breeding applications to reduce aflatoxin contamination in peanut and beyond.