title: Sexual reproduction in Aspergillus tubingensis from section Nigri.
abstract: A sclerotium-forming member of Aspergillus section Nigri was sampled from a population in a single field in North Carolina, USA, and identified as A. tubingensis based on genealogical concordance analysis. Aspergillus tubingensis was shown to be heterothallic, with individual strains containing either a MAT1-1 or MAT1-2 mating-type gene. Strains of opposite mating type were crossed on mixed cereal agar and incubated for 5-6 months. Stromata typically formed 1-2 indehiscent ascocarps containing asci and ascospores within the pseudo-parenchymatous matrix in a manner similar to the Petromyces sexual stage from section Flavi, which is closely related to section Nigri. Ascospores of A. tubingensis differed from those of section Flavi species in the reticulate ornamentation of ascospores and the presence of two crests that form an equatorial furrow. Sexual reproduction in A. tubingensis may be useful for enhancing enzyme and organic acid production through recombination-mediated genetic engineering of industrial strains.
authors.affiliation: National Peanut Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Dawson, Georgia 39842.
authors.forename: Bruce W
authors.initials: BW
authors.lastname: Horn
authors.forename: Rodrigo A
authors.initials: RA
authors.lastname: Olarte
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Peterson
authors.forename: Ignazio
authors.initials: I
authors.lastname: Carbone
mesh_terms: D001230:Aspergillus / Q000145:classification / Q000166:cytology / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D049770:Genes, Mating Type, Fungal / Q000235:genetics*; D008969:Molecular Sequence Data; D009657:North Carolina; D010802:Phylogeny; D012098:Reproduction; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D013172:Spores, Fungal
chemical_list: D004271:DNA, Fungal
keywords: A. niger; Aspergillus flavus; ascospores; heterothallism; mating type; sclerotium; stroma