EFS12- Book of abstracts - Contact
EFS12- Book of abstracts - Contact
EFS12- Book of abstracts - Contact
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SESSION 1: FUSARIUM – GENETICS, GENOMICS AND SYSTEMS BIOLOGY<br />
Molecular network <strong>of</strong> nitrate sensing and assimilation<br />
in Fusarium fujikuroi<br />
A. Pfannmüller 1 , P. Wiemann 1,2 , B. Tudzynski 1<br />
1 Institut für Biologie und Biotechnologie der Pflanzen, Westfälische Wilhelms-Universität Münster,<br />
Schlossplatz 8, Münster, Germany ; 2 Department <strong>of</strong> Medical Microbiology and Immunology, University<br />
<strong>of</strong> Wisconsin-Madison, WI, United States<br />
E-mail: a_pfan02@uni-muenster.de<br />
The phytopathogenic ascomycete Fusarium fujikuroi produces a broad spectrum<br />
<strong>of</strong> interesting secondary metabolites, including the agriculturally applied plant<br />
hormone gibberellic acid (GA3), the red pigment bikaverin and the fungal toxin<br />
fusarin C. The biosynthesis <strong>of</strong> these three secondary metabolites depends greatly<br />
on the amount and quality <strong>of</strong> the available nitrogen source. At high nitrogen<br />
concentrations, the biosynthesis <strong>of</strong> gibberellins and bikaverin are repressed on<br />
the transcriptional level, while fusarin C genes are repressed at nitrogen<br />
starvation conditions. Because <strong>of</strong> this impact on secondary metabolism, the<br />
detailed understanding <strong>of</strong> the nitrogen sensing and regulatory network in<br />
F. fujikuroi is <strong>of</strong> great interest.<br />
Previous work has shown that F. fujikuroi is able to sense the availability <strong>of</strong><br />
ammonium by the ammonium-transporter MepB and the glutamine synthetase<br />
GS. However, it is not known if nitrate is sensed as a separate nitrogen source or<br />
+<br />
after its metabolization to NH4 and glutamine. Therefore, we analyzed<br />
orthologues <strong>of</strong> the Aspergillus nidulans nitrate-specific activator NirA, the nitrate<br />
reductase NiaD and the nitrate transporter NrtA, to gain more insights on the<br />
nitrate sensing and assimilation process in F. fujikuroi. We show the impact <strong>of</strong><br />
FfNirA on the expression <strong>of</strong> certain nitrate-assimilatory genes and its subcellular<br />
localization depending on the nitrogen availability and the activity <strong>of</strong> putative<br />
nitrate sensors. Since the deletion <strong>of</strong> ffnirA, but not ffniaD led to a deregulation<br />
effect on secondary metabolism under nitrate sufficient conditions, we are<br />
investigating the putative role <strong>of</strong> FfNrtA as a nitrate transceptor and screen for<br />
additional FfNirA-controlled genes that might be involved in the nitrate sensing <strong>of</strong><br />
F. fujikuroi.<br />
Keywords: Fusarium fujikuroi, secondary metabolism, nitrate, sensing<br />
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