ARS | Publication request: PHYLOGENETIC AND MORPHOLOGICAL ANALYSIS OF ASPERGILLUS OCHRACEOROSEUS

Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 25, 2003
Publication Date: June 1, 2003
Citation: Klich, M.A., Cary, J.W., Beltz, S.B., Bennett, C.A. 2003. Phylogenetic and morphological analysis of Aspergillus ochraceoroseus. Mycologia. 95:1252-1260.

Interpretive Summary: Aflatoxin and sterigmatocystin are related poisons produced by a number of mold species in the genus Aspergillus. Aflatoxin is the more toxic of the two, and allowable levels are regulated by governments around the world at between 5 and 20 parts per billion in foods intended for human consumption. Aspergillus ochraceoroseus has recently been found to produce both aflatoxin and sterigmatocystin. This is important because this species does not seem to be related to other species that produce these toxins. Discovery of a common link among all aflatoxin/sterigmatocystin producing species could lead to new approaches for controlling these toxins. There is also concern that the aflatoxin/sterigmatocystin genes could move from one species to another. In this paper, we show that A. ochraceoroseus produces its toxins in a way more similar to those of the sterigmatocystin-producers than the aflatoxin-producers and that this species did not acquire this ability in an evolutionarily recent transfer from another species. This research will benefit researchers in mycotoxicology and fungal phylogenetics.

Technical Abstract: Aspergillus ochraceoroseus produces the yellow-gold conidia and other characteristics of Aspergillus subgenus Circumdati section Circumdati. However, it produces aflatoxin, a secondary metabolite characteristic of some members of Aspergillus subgenus Circumdati section Flavi and sterigmatocystin, a related secondary metabolite usually associated with Aspergillus subgenus Nidulantes sections Nidulantes and Versicolores, and members of several other genera. Our morphological data supports the placement of A. ochraceoroseus in subgenus Circumdati. We compared molecular sequence data from A. ochraceoroseus aflatoxin and sterigmatocystin genes aflR and nor-1/stcE, as well as 5.8S ITS and beta tubulin genes, to that of aspergilli in sections Circumdati, Flavi, Nidulantes, and Versicolores. In the sequence comparisons, A. ochraceoroseus was more closely related to the species in subgenus Nidulantes than to species from subgenus Circumdati.