Plant Fungi Interactions (prof. Bruno Cammue)
Research at PFI was initiated in the early 1990s with an extensive screening for novel antimicrobial plant peptides, and resulted in the discovery of several types of novel antifungal proteins. On one of them, named the plant defensins (PDFs), pioneering research was continued. PDFs are small, basic, cysteine-rich antifungal peptides that are structurally related to insect and mammalian defensins. They are active against a broad range of phytopathogenic fungi (e.g. Botrytis cinerea, Fusarium spp., Alternaria spp.) and even human pathogens (e.g. Candida albicans and Aspergillus flavus), whereas they are nontoxic to plant and mammalian cells. Primarily based on PDFs studies, research at PFI was further developed in the late 1990s in two distinct research units, focussed on either side of the plant-fungus interaction.
PFI-Plant research unit (coordinated by dr. Janick Mathys and dr. Barbara De Coninck)
The discovery of different types of PDFs in Arabidopsis thaliana significantly stimulated our research on their expression and function. For example, the discovery of the plant defensin AtPDF1.2a and the corresponding signaling pathways involved in its induction broadened the general insight in induced defense mechanisms in plants. The corresponding gene is now world-wide used as a marker for ethylene/jasmonate controled responses in plants. To support this research also different molecular tools and approaches were developed optimizing plant transformation and molecular breeding.
Current research is still focussing on (> 320) PDF-like peptides in Arabidopsis using genome-wide approaches such Tiling Array technology, primarily aiming at discovering their in planta role. This research is recently broadened to other types of stress-induced peptides (SIPs). Our expertise on resistance mechanisms, mainly in A. thaliana and focusing on resistance to necroptrophic fungi, allowed us to successfully use this model plant as a source of resistance traits against agronomically important crops/diseases (e.g. Fusarium oxysporum in banana, Cercospora beticola in sugarbeet). Based on the same expertise 3 years ago we also initiated research on defense mechanisms induced by biocontrol organisms, the so-called induced systemic response (ISR). This research is based on transcriptome studies both in a model plant (A. thaliana) and in crops (e.g. tomato, lettuce), involves both biotic and abiotic biocontrol agents and is mainly directed to different necroptrophic pathogens.
PFI-Fungus/yeast unit (coordinated by dr. Karin Thevissen and dr. Klaartje Pellens)
Using genetic screens and specific biochemical assays, mainly on the model yeast Saccharomyces cerevisiae, we were able to unravel the mode of antifungal activity (MOA) of some PDFs, including the discovery of specific sphingolipids as primary binding sites in the fungal membrane, the induction of reactive oxigen species and subsequent apoptosis, and membrane permeabilization. Currently we are still refining this MOA for specific PDFs and extrapolate them to both important plant pathogens (e.g. Fusarium oxysporum) and human pathogens (e.g. Candida albicans). The latter findings allowed us to extend this research for synthetic antimycotic compounds, and on different tolerance/resistance mechanisms occurring in both fungal planktonic cells and biofilms. Based on accumulated expertise, we are now collaborating with the Centre for Drug Discovery and Design (CD3, K.U.Leuven) aiming at the development of novel antimycotic or anti-apoptotic compounds through large-scale screening of selected compound libraries, structure-activity relationship studies and general drugability tests.
