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SESSION 1: FUSARIUM – GENETICS, GENOMICS AND SYSTEMS BIOLOGY
P3 - Significance of the hydrophobin FgHyd5p in
Fusarium graminearum
E. Minenko, R. F. Vogel, L. Niessen
Technische Universität München, Lehrstuhl für Technische Mikrobiologie, Weihenstephaner Steig 16,
85350 Freising, Germany.
E-mail: Ekaterina.Minenko@wzw.tum.de
Fusarium graminearum and Fusarium culmorum are causative agents of beer
gushing. Class II hydrophobins have been demonstrated to induce it.
Hydrophobins are a group of small secreted proteins ubiquitously found in
filamentous fungi. Some hydrophobins were shown to have functions in fungal
development, while others seem to lack known function. Also, cellular functions of
FgHyd5p are still unknown. FgHyd5p, the F. graminearum homologue to FcHyd5p
(F. culmorum) is a small secreted protein typified by the presence of 8 cysteine
residues at conserved positions. FgHyd5p is characterized by formation of low
stability aggregates and solubility in organic solvents. We showed that FgHyd5p
does not have an effect on morphology of F. graminearum since colony
morphology and growth rate, hyphal length and diameter as well as biomass
production were shown to stay unaffected in Fg∆hyd5 knockout strains. Knockout
of the fghyd5 gene causes a reduction of spore length and an increase in spore
numbers. Using an F. graminearum reporter strain expressing sGFP under the
control of the Phyd5 promoter we found that FcHyd5p was not expressed in
media with different carbon or nitrogen sources, respectively. Moreover we did not
observe any pH dependent fghyd5 gene expression. FgHyd5p showed an effect
on the hydrophobicity of hyphae resulting in an easy wettable phenotype of
transformants. Results of our studies also showed that FgHyd5p has an effect on
the virulence of F. graminearum. Wheat and barley plants infected with spores
from an Fg∆hyd5 knockout strain at EC 0-9 were significantly longer in EC 12 as
compared to plants that were infected with the F. graminearum parent strain.
Using the F. graminearum sGFP reporter strain and histological analysis we
showed that the gene is expressed during plant infection and may thus play a role
as a virulence factor during the infection of cereals.
Keywords: Fusarium, hydrophobin, expression, virulence
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