As the number of fungal genome sequenced increase, the number of proteomics studies increase the same way. The studies are driven for various reasons, but some of them are devoted to the identification of proteins produced (and most frequently secreted) by fungi

Fig. 3. Expression of the genome of Fusarium graminearum when grown on different carbon sources. Microarrays were analyzed and the number of genes overexpressed (p<0.02, fold change >2) comparatively that after growth on glucose where determined (Table). The graph represents the repartition of the CWDE (cellulases in yellow, hemicellulases in pink and pectinases in green) as a function of the substrate used for growth.

in response to plant material. This fact fits well with the purpose of this chapter and is perfectly summarized by the title of a recent paper: "Plant-pathogen interactions: what is proteomics telling us" (Mehta et al., 2008). In this paper, is shown that when pathogens are in the presence of plants, their metabolism is changed to secrete proteins, including CWDE, potentially involved in plant cell wall degradation. These findings are in perfect accordance with the conclusion of the transcriptomics studies (see previous section).

We performed a proteomics study with the plant pathogen Fusarium graminearum grown either on glucose or on a preparation of plant cell wall as the sole carbon source (Phalip et al., 2005). When it is grown on glucose (Fig. 4.), the fungus secretes a few proteins in small quantities. When the more complex and diverse plant cell wall is used, the fungus reacts by secreting a much higher amount of more diverse proteins. Approximately half (45%) of these are putative CWDE. Furthermore, CWDE identified are able to take in charge the three cell wall layers: cellulose (11 proteins are putative cellulases), hemicellulose (25) and pectin (19). These results are also perfectly correlated with transcriptome studies. The fungus clearly responds to cell wall diversity by enzyme diversity. It could be a good point to keep in mind when looking for an enzyme cocktail for biomass valorization.

Fig. 4. Proteomics studies of Fusarium graminearum grown on glucose (A) and plant cell wall (B). Culture supernatants were concentrated and the equivalent of the same volume of supernatant was loaded on SDS-PAGE (C). The corresponding proteins were by identified by Mass Spectrometry and classified thanks to their homologies with protein in databases (D). The CWDE were further considered as a function of the cell wall layer they degrade (E).