Impact of an Antifungal Insect Defensin on the Proteome of the Phytopathogenic Fungus Botrytis cinerea

ETD151, an analogue
of the antifungal insect defensin heliomicin,
is an antifungal peptide active against yeasts and filamentous fungi.
To decipher the mechanisms underlying its molecular action on the
phytopathogenic fungus Botrytis cinerea, a necrotrophic pathogen responsible for gray mold disease, we investigated
the changes in 3 day-old mycelia upon treatment with different concentrations
of ETD151. Optical and fluorescence microscopies were used prior to
establishing the peptide/protein profiles through two mass spectrometry
approaches: MALDI profiling, to generate molecular mass fingerprints
as peptide signatures, and a gel-free bottom-up proteomics approach.
Our results show that a concentration of ETD151 above the half-maximal
inhibitory concentration can alter the integrity of the mycelial structure
of B. cinerea. Furthermore, reproducible
modifications of the peptide/protein composition were demonstrated
in the presence of ETD151 within a 1500–16,000 mass (m/z) range. After the robustness of LC-ESI-MS/MS analysis
on B. cinerea mycelial extracts was
confirmed, our analyses highlighted 340 significantly modulated proteins
upon treatment with ETD151 within a 4.8–466 kDa mass range.
Finally, data mapping on KEGG pathways revealed the molecular impact
of ETD151 on at least six pathways, namely, spliceosome, ribosome,
protein processing in endoplasmic reticulum, endocytosis, MAPK signaling
pathway, and oxidative phosphorylation.