Nathan W Gross-Thesis Abstract
Published on: Mar 3, 2016
Transcripts - Nathan W Gross-Thesis Abstract
INFLUENCES OF COMBINATORIALLY SELECTED PEPTIDES ON INHIBITIOIN OF
GIBBERELLA ZEAE SPORE GERMINATION AND CYTOLOGICAL MODIFICATION OF
Nathan W Gross
Prof. James T English, Thesis Supervisor
The ascomycete Gibberella zeae causes the head blight of wheat, a floral disease that
reduces kernel weight, limits yield, and induces mycotoxin accumulation. To develop novel
disease-management strategies, peptides were affinity selected from phage-display combinatorial
libraries against G. zeae macroconidia to identify molecules that inhibit spore germination.
Two peptides, f3-16 and f8-18, were identified that significantly inhibited spore
germination and germ-tube growth. Experiments were conducted to evaluate how the inhibitory
peptide f3-16 affects constituents of the germ-tube apical cell that are important for polarized
elongation, including endocytic system components, sterol-rich plasma membrane domains
(SRD), and patterns of cell wall deposition.
When incubated without f3-16, G. zeae germ-tubes were stained to visualize plasma
membrane, endocytic vesicles, endosomes, and the Spiztenkörper. These components were
stained in the same temporal sequence that was observed in other filamentous fungi. Staining of
SRDs and cell-wall chitin also agreed with previous observations in other fungi.
The peptide f3-16 caused endosomes to densely accumulate within the germ-tube
cytoplasm, and vacuole formation appeared to be inhibited. The distributions of SRDs and chitin
were also altered in germ-tubes incubated with the peptide.
This study provides the first description of cytological changes in germinating ascospores
induced by a combinatorially selected inhibitory peptide. Characterization of these cytological
phenotypes provides the groundwork for mechanistic studies of inhibitory peptides.