Affiliation:
1. Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907
Abstract
ABSTRACT
Fumonisins are a group of mycotoxins that contaminate maize and cause leukoencephalomalacia in equine, pulmonary edema in swine, and promote cancer in mice. Fumonisin biosynthesis in
Fusarium verticillioides
is repressed by nitrogen and alkaline pH. We cloned a
PACC
-like gene (
PAC1
) from
F. verticillioides
.
PACC
genes encode the major transcriptional regulators of several pH-responsive pathways in other filamentous fungi. In Northern blot analyses, a
PAC1
probe hybridized to a 2.2-kb transcript present in
F. verticillioides
grown at alkaline pH. A mutant of
F. verticillioides
with a disrupted
PAC1
gene had severely impaired growth at alkaline pH. The mutant produced more fumonisin than the wild type when grown on maize kernels and in a synthetic medium buffered at an acidic pH, 4.5. The mutant, but not the wild type, also produced fumonisin B
1
when mycelia were resuspended in medium buffered at an alkaline pH, 8.4. Transcription of
FUM1
, a gene involved in fumonisin biosynthesis, was correlated with fumonisin production. We conclude that
PAC1
is required for growth at alkaline pH and that
Pac1
may have a role as a repressor of fumonisin biosynthesis under alkaline conditions.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
139 articles.
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