Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 3, 2010
Publication Date: January 7, 2011
Citation: Horn, B.W., Moore, G.G., Carbone, I. 2011. Sexual reproduction in aflatoxin-producing Aspergillus nomius. Mycologia. 103910:174-183. Interpretive Summary: Aflatoxins are highly carcinogenic toxins produced by several molds before harvest and during storage in corn, peanuts, cottonseed, tree nuts and other crops. Aspergillus nomius is a potent producer of aflatoxins and was formerly considered to be strictly nonsexual in reproduction. In this paper we describe the newly discovered sexual stage in the life cycle of the mold. The sexual stage might account for much of the genetic variation in A. nomius populations in the field and will be an important factor in devising new strategies for controlling aflatoxin contamination.
Technical Abstract: Sexual reproduction was examined in the aflatoxin-producing fungus Aspergillus nomius. Crosses between sexually compatible strains resulted in the formation of multiple nonostiolate ascocarps within stromata, which places the teleomorph in the genus Petromyces. Ascocarp and ascospore morphology in P. nomius were similar to P. flavus and P. parasiticus and differences between teleomorphs were insufficient for species separation. Formation of mature ascocarps was infrequent, with only 24% of the 83 crosses producing viable ascospores. The majority of P. nomius strains contained a single mating-type gene (MAT1-1 or MAT1-2), but several strains contained both genes. MAT1-1/MAT1-2 strains were self sterile and capable of mating with both MAT1-1 and MAT1-2 strains; hence, P. nomius appears to be functionally heterothallic.