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ARS Home » Research » Publications at this Location » Publication #84044


item Peterson, Stephen

Submitted to: International Workshop on Penicillium and Aspergillus
Publication Type: Proceedings
Publication Acceptance Date: 5/19/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: The mold group Aspergillus contains species used industrially to make foods and food additives, and also other species that make carcinogenic toxins in commodities. The conventional methods for identifying these molds (such as color and growth on agar) are unreliable. Genetic material (DNA sequences) was analyzed and shown to provide a very reliable method for distinguishing the valuable and harmful molds. The natural relationships of these molds were determined from this new data. Knowing relationships will help researchers predict which species have useful agricultural and industrial properties.

Technical Abstract: Aspergillus taxonomy is based on morphological and physiological similarities. To test the current phenotype-based classification systems, I have sequenced the D1 and D2 regions of the large subunit ribosomal RNA (lsu-rDNA) genes from about 240 named taxa in Aspergillus. Data were analyzed by parsimony and maximum likelihood methods. Apical regions of the trees were generally well supported in bootstrap analysis, but basal regions of the resulting trees are not. The consensus tree of the species shows that the Aspergillus species occur on three major branches. The maximum parsimony trees are incompatible with the current subgeneric taxonomy of Aspergillus. Accordingly, the three major lineages are given subgeneric rank as subgenera Aspergillus, Nidulantes and Fumigati. A few of the sections (Gams et al. 1985) are monophyletic, but most are revised to reflect the phylogeny of the species. The revised subgenus Fumigati contains sections Fumigati and Clavati, in contrast to their current placement in separate subgenera. Hemicarpenteles acanthosporus (section Ornati) also belongs in subgenus Fumigati, section Clavati. Subgenus Nidulantes contains the Emericella species, some species from sections Versicolores, Usti, Sparsi and Ornati. Subgenus Aspergillus contains sections Restricti, Aspergillus, Flavi, Nigri, Circumdati, Terrei, Flavipedes, and Cervini. Some species synonymies are suggested by identical lsu-rDNA sequences.