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Applied and Environmental Microbiology, August 2000, p. 3421-3426, Vol. 66, No. 8
Department of Agricultural and Environmental
Biology, The University of Tokyo, Bunkyo-ku, Tokyo
113-8657,1 Bio-oriented Technology
Research Advancement Institution (BRAIN), Nisshin, Ohmiya, Saitama
331-0044,2 National Institute of
Fruit Tree Science, Akitsu, Hiroshima 729-2494,3
and Faculty of Agriculture, Ibaraki University, Ami-machi,
Ibaraki 300-0393,4 Japan
Received 15 October 1999/Accepted 1 June 2000
We investigated the mechanism of resistance to demethylation
inhibitors (DMI) in Penicillium digitatum by isolating the
CYP51 gene, which encodes the target enzyme
(P45014DM) of DMI, from three DMI-resistant and three
DMI-sensitive strains. The structural genes of all six strains were
identical, but in the promoter region, a unique 126-bp sequence was
tandemly repeated five times in the DMI-resistant strains and was
present only once in the DMI-sensitive strains. Constitutive expression
of CYP51 in the resistant strains was about 100-fold higher
than that in the sensitive strains. We introduced CYP51,
including the promoter region, from a DMI-resistant strain into a
DMI-sensitive strain, which rendered the transformants DMI resistant
and increased CYP51 expression. We also found that if the
number of copies of the repeat was reduced to two, resistance and
CYP51 expression also decreased. These results indicate
that the 126-bp unit acts as a transcriptional enhancer and that a tandem repeat of the unit enhances CYP51 expression,
resulting in DMI resistance. This is a new fungicide resistance
mechanism for filamentous fungi.
0099-2240/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Tandem Repeat of a Transcriptional Enhancer
Upstream of the Sterol 14
-Demethylase Gene (CYP51) in
Penicillium digitatum
*
Corresponding author. Mailing address: Laboratory of
Plant Pathology, Department of Agricultural and Environmental Biology, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan. Phone: 81-3-5841-5054. Fax: 81-3-5841-5090. E-mail:
hirohama{at}ims.u-tokyo.ac.jp.
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