Advances in molecular and genomic research to safeguard food and feed supply from aflatoxin contamination

Abstract

Worldwide recognition that aflatoxin contamination of agricultural commodities by the fungus Aspergillus flavus is a global problem has significantly benefitted from global collaboration for understanding the contaminating fungus, as well as for developing and implementing solutions against the contamination. The effort to address this serious food and feed safety issue has led to a detailed understanding of the taxonomy, ecology, physiology, genomics and evolution of A. flavus, as well as strategies to reduce or control pre-harvest aflatoxin contamination, including (1) biological control, using atoxigenic aspergilli, (2) proteomic and genomic analyses for identifying resistance factors in maize as potential breeding markers to enable development of resistant maize lines, and (3) enhancing host-resistance by bioengineering of susceptible crops, such as cotton, maize, peanut and tree nuts. A post-harvest measure to prevent the occurrence of aflatoxin contamination in storage is also an important component for reducing exposure of populations worldwide to aflatoxins in food and feed supplies. The effect of environmental changes on aflatoxin contamination levels has recently become an important aspect for study to anticipate future contamination levels. The ability of A. flavus to produce dozens of secondary metabolites, in addition to aflatoxins, has created a new avenue of research for understanding the role these metabolites play in the survival and biodiversity of this fungus. The understanding of A. flavus, the aflatoxin contamination problem, and control measures to prevent the contamination has become a unique example for an integrated approach to safeguard global food and feed safety.

The Transcriptional Regulator Hbx1 Affects the Expression of Thousands of Genes in the Aflatoxin-Producing FungusAspergillus flavus

“…Once the fungus has colonized the crop it can survive in the field under harsh conditions for several years by forming resistant structures termed sclerotia (Horn et al , 2014). Upon colonization of the plant, A. flavus produces a number of mycotoxins, including the highly carcinogenic family of toxins known as aflatoxins (Bhatnagar et al , 2018). Contaminated crops are often destroyed or significantly reduced in value leading to substantial economic losses in the range of one billion US dollars annually during years of severe aflatoxin outbreaks (Robens & Cardwell 2003, & Wu et al 2008).…”

Genetic regulation of aflatoxin, ochratoxin A, trichothecene, and fumonisin biosynthesis: A review

“…The gene aflS is located adjacent to aflR, and there is no significant similarity between its putative product and any other proteins found in databases. The gene aflS is clearly involved in aflatoxin regulation since deletion mutants do not produce aflatoxins and the levels of expression of some genes of the aflatoxin pathway are significantly reduced (Yu and Ehrlich 2011;Bhatnagar et al 2018). Chang (2003) suggested that aflS might be modulating aflatoxin biosynthesis by interacting with aflR although the exact role of aflS has not yet been made clear (Bhatnagar et al 2018).…”

Current Status and Future Opportunities of Omics Tools in Mycotoxin Research

“…The results showed that isolates which produced higher levels of aflatoxin exhibited fewer differentially expressed genes in increased stress conditions. Thus, secondary metabolites including aflatoxins may be produced as a response to the oxidative stress conditions [ 130 ]. For Ochratoxin, a recent review of transcriptomic studies indicated that the transcriptomic studies carried out do not clarify the modes of action of OTA but have contributed to relevant toxicological information.…”