Promoter Sequence Mutations in the aflR Gene of Aspergillus flavus are Correlated with the Production of Aflato

Abstract: For a better understanding of aflatoxin biosynthesis in some aspergillus strains， the mutation in the aflR (aflatoxin biosynthetic pathway regulatory gene) promoter region of none-aflatoxin B1-producing Aspergillus flavus (A.flavus) strains was investigated. For each strain cultured in medium suitable for aflatoxin production， the ELISA was performed to detect the aflatoxin B1 level and the total RNA was extracted and then the RT-PCR was carried out to evaluate the aflR mRNA level. The aflR promoter region was amplificated by PCR and then sequenced. Our experiment results showed that the aflR mRNA level was noticeably high in all the six aflatoxin B1-producing A.flavus strains while the aflR mRNA level was either low or rare in the two none-aflatoxin B1-producing A.flavus strains. Some mutation points at _90， _236， _253， _262 and _282 in the aflR promoter region were revealed in none-aflatoxin B1-producing A.flavus strains through analyzing via a gene software. In addition， the experiment results from Aspergillus oryzae strains were coincident with those of none-aflatoxin B1-producing A.flavus strains. And the results from the Aspergillus parasiticus strain were concordant with those of aflatoxin B1-producing A.flavus strains. All these data indicate that one or some of the mutation sites described above in the aflR promoter region from A.flavus strains may be correlated to the aflatoxin production.

CSTR: 32200.14.cjcb.2006.06.0027