title: Aspergillus oryzae strains with a large deletion of the aflatoxin biosynthetic homologous gene cluster differentiated by chromosomal breakage.
abstract: Recently we divided Aspergillus oryzae RIB strains into group 1, having seven aflatoxin biosynthesis homologous genes (aflT, nor-1, aflR, norA, avnA, verB, and vbs), and group 2, having three homologues (avnA, verB, and vbs). Here, partial aflatoxin homologous gene cluster of RIB62 from group 2 was sequenced and compared with that of RIB40 from group 1. RIB62 showed a large deletion upstream of ver-1 with more than half of the aflatoxin homologous gene cluster missing including aflR, a positive transcriptional regulatory gene. Adjacent to the deletion of the aflatoxin homologous gene cluster, RIB62 has a unique sequence of about 8 kb and a telomere. Southern analysis of A. oryzae RIB strains with four kinds of probe derived from the unique sequence of RIB62 showed that all group 2 strains have identical hybridizing signals. Polymerase chain reaction with specific primer set designed to amplify the junction between ver-1 and the unique sequence of RIB62 resulted in the same size of DNA fragment only from group 2 strains. Based on these results, we developed a useful genetic tool that distinguishes A. oryzae group 2 strains from the other groups' strains and propose that it might have differentiated from the ancestral strains due to chromosomal breakage.
authors: Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashihiroshima, Hiroshima, 739-8530, Japan.
authors: Yun-Hae
authors: YH
authors: Lee
authors: Mihoko
authors: M
authors: Tominaga
authors: Risa
authors: R
authors: Hayashi
authors: Kazutoshi
authors: K
authors: Sakamoto
authors: Osamu
authors: O
authors: Yamada
authors: Osamu
authors: O
authors: Akita