title: High sequence variations in the region containing genes encoding a cellular morphogenesis protein and the repressor of sexual development help to reveal origins of Aspergillus oryzae.
abstract: Aspergillus oryzae and Aspergillus flavus are closely related fungal species. The A. flavus morphotype that produces numerous small sclerotia (S strain) and aflatoxin has a unique 1.5 kb deletion in the norB-cypA region of the aflatoxin gene cluster (i.e. the S genotype). Phylogenetic studies have indicated that an isolate of the nonaflatoxigenic A. flavus with the S genotype is the ancestor of A. oryzae. Genome sequence comparison between A. flavus NRRL3357, which produces large sclerotia (L strain), and S-strain A. flavus 70S identified a region (samA-rosA) that was highly variable in the two morphotypes. A third type of samA-rosA region was found in A. oryzae RIB40. The three samA-rosA types were later revealed to be commonly present in A. flavus L-strain populations. Of the 182 L-strain A. flavus field isolates examined, 46%, 15% and 39% had the samA-rosA type of NRRL3357, 70S and RIB40, respectively. The three types also were found in 18 S-strain A. flavus isolates with different proportions. For A. oryzae, however, the majority (80%) of the 16 strains examined had the RIB40 type and none had the NRRL3357 type. The results suggested that A. oryzae strains in the current culture collections were mostly derived from the samA-rosA/RIB40 lineage of the nonaflatoxigenic A. flavus with the S genotype.
authors.affiliation: Southern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, New Orleans, LA 70124, United States. Electronic address: perngkuang.chang@ars.usda.gov.
authors.forename: Perng-Kuang
authors.initials: PK
authors.lastname: Chang
authors.affiliation: Southern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, New Orleans, LA 70124, United States.
authors.forename: Leslie L
authors.initials: LL
authors.lastname: Scharfenstein
authors.affiliation: Biological Control of Pests Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Stoneville, MS 38776, United States.
authors.forename: Cesar D
authors.initials: CD
authors.lastname: Solorzano
authors.affiliation: Biological Control of Pests Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Stoneville, MS 38776, United States.
authors.forename: Hamed K
authors.initials: HK
authors.lastname: Abbas
authors.affiliation: Western Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Albany, CA, 94710, United States.
authors.forename: Sui-Sheng T
authors.initials: SS
authors.lastname: Hua
authors.affiliation: Biological Control of Pests Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Stoneville, MS 38776, United States.
authors.forename: Walker A
authors.initials: WA
authors.lastname: Jones
authors.affiliation: Crop Production Systems Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Stoneville, MS 38776, United States.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Zablotowicz
mesh_terms: D000348:Aflatoxins / Q000235:genetics; D001236:Aspergillus oryzae / Q000145:classification / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D014644:Genetic Variation; D005838:Genotype; D005810:Multigene Family; D010802:Phylogeny
chemical_list: D000348:Aflatoxins; D001426:Bacterial Proteins
keywords: Aspergillus flavus; Aspergillus oryzae; Deletion; Genome; Recombination