Transcript of a homolog of aflR, a regulatory gene for aflatoxin synthesisin Aspergillus parasiticus, was not detected in Aspergillus oryzae strains

Some strains of Aspergillus oryzae were shown to have homologs of aflR, a r egulatory gene for aflatoxin synthesis in Aspergillus parasiticus. Transcri ption of an aflR homolog was examined in sis strains of A. oryzae having th e homologs, using polymerase chain reaction (PCR) coupled with reverse tran scription. No PCR product was obtained when the RNA prepared from the A. or yzae strains cultivated under aflatoxin-producing condition was used as tem plate for amplification of the aflR cDNA. By contrast, a PCR product of the expected size was obtained with RNA from A. parasiticus NIAH-26 processed by the same procedure. From genomic DNA of these strains, PCR products of t he same size as above were obtained. Possible degradation of the aflR mRNA in the RNA preparation of the A. oryzae strains was negligible, because the calmodulin transcript was detected by PCR from the same RNA samples. Thus, the aflR homologs in the non-aflatoxigenic A. oryzae strains examined are not expressed even under aflatoxin-producing condition. (C) 1998 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.