Molecular profile of non‑afatoxigenic phenotype in native strains of Aspergillus favus.

Afatoxins are the most common mycotoxin contaminant reported in food and feed. Afatoxin B1, the most toxic among
diferent afatoxins, is known to cause hepatocellular carcinoma in animals. Aspergillus favus and A. parasiticus are the
main producers of afatoxins and are widely distributed in tropical countries. Even though several robust strategies have
been in use to control afatoxin contamination, the control at the pre-harvest level is primitive and incompetent. Therefore,
the aim of the study was to isolate and identify the non-afatoxigenic A. favus and to delineate the molecular mechanism
for the loss of afatoxin production by the non-afatoxigenic isolates. Eighteen non-afatoxigenic strains were isolated from
various biological sources using cultural and analytical methods. Among the 18 isolates, 8 isolates produced sclerotia and
17 isolates had type I deletion in norB-cypA region. The isolates were confrmed as A. favus using gene-specifc PCR and
sequencing of the ITS region. Later, afatoxin gene-specifc PCR revealed that the defect in one or more genes has led to nonafatoxigenic phenotype. The strain R9 had maximum defect, and genes avnA and verB had the highest frequency of defect
among the non-afatoxigenic strains. Further, qRT-PCR confrmed that the non-afatoxigenic strains had high frequency of
defect or downregulation in the late pathway genes compared to early pathway genes. Thus, these non-afatoxigenic strains
can be the potential candidates for an efective and profcient strategy for the control of pre-harvest afatoxin contamination.