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Plant pathogens face different environmental clues depending on the stage of the infection cycle they are in. Fusarium graminearum infects small grain cereals producing trichothecenes type B (TB) that act as virulence factor in the interaction with the plant and have important food safety implications. This study addresses at the proteomic level the effect of an environmental stimulus (such as the presence of a polyamine like agmatine) possibly encountered by the fungus when it is already within the plant. Because biological diversity affects the proteome significantly, a multistrain (n=3) comparative approach was used to identify consistent effects caused on the fungus by the nitrogen source (agmatine or glutamic acid). Proteomics analyses were performed by the use of 2D-DIGE. Results showed that agmatine augmented TB production but not equally in all strains. The polyamine reshaped drastically the proteome of the fungus activating specific pathways linked to the translational control within the cell. Chromatin restructuring, ribosomal regulations, protein and mRNA processing enzymes were modulated by the agmatine stimulus as well as metabolic, structural and virulence-related proteins, suggesting the need to reshape specifically the fungal cell for TB production, a key step for the pathogen spread within the spike., Biological Significance: Induction of toxin synthesis by plant compounds plays a crucial role in toxin contamination of food and feed, in particular trichothecenes type B produced mainly by F. graminearum on wheat. This work describes the level of diversity of 3 strains facing 2 toxin inducing plant derived compounds. This knowledge is of use for the research community on toxigenic Fusarium strains in cereals for understanding the role of fungal diversity in toxin inducibility. This work also suggests that environmental clues that can be found within the plant during infection (like different nitrogen compounds) are crucial stimuli for reshaping the proteome profile and consequently the specialization profiling of the fungus, ultimately leading to very different toxin contamination levels in the plant., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The response of two willow clones (Salix fragilis (Sf) and Salix aurita (Sa)) to the presence of metals (Zn, Cu, Cd, Ni) was studied. Rooted cuttings were planted in control and contaminated soil. After 100days, different parameters (biomass, chlorophyll fluorescence (Fv/Fm), pigment and sugar concentrations, electrolyte leakage and proteome-level changes) were analyzed. The growth of Sa was not influenced by metals whereas Sf produced significantly less biomass when exposed to the pollutants. Furthermore, although Sa did not show a growth reduction in the presence of metals, the overall view of the physiological results among others the changes in the accumulation of sugars and pigments indicated that metals had a more severe impact on this clone. The response at the proteome level confirmed these observations. The growth reduction and the proteomic changes in Sf indicate that this clone adjusts its metabolism to maintain cellular homeostasis. Sa on the contrary maintains growth but the physiological and proteomics data suggests that this can only be done at the cost of cellular deregulation. Therefore high biomass is not linked with a good tolerance strategy. In a long-term study the survival of Sa might be compromised making it a poorer candidate for phytoremediation efforts., Biological Significance: In the last centuries human activity has resulted in the dispersal of heavy metals with potential phytotoxic effects over large areas. The increased knowledge of the responses of Salix-species, a group of trees with potential as biomass producer but also as phytoremediation agent, when growing on metal-polluted substrate provided by this study has the potential to help in the improved selection of clones with more or less potential for these aims. Contrary to most studies the trees in the current study were exposed to a mixture of metals, thereby facing a closer resemblance to the situation on soils polluted by human activity. Whereas many papers focused on the two main phenotypic characteristics (biomass and accumulation), fewer papers studied proteomic and physiological parameters which allow to have a global view of the tolerance of probable willow candidates for phytoremediation purposes. Our data demonstrates that higher biomass production in presence of metals is not necessarily linked with higher tolerance whereas growth reduction might indicate longer long-term tolerance. In the long term and in the purpose of a future use in phytoremediation, the survival of this high producer clone could be compromised., (Copyright © 2014 Elsevier B.V. All rights reserved.)

A 2D-DIGE proteomics experiment was performed to describe the mechanism underlying the production of geosmin, an earthy-smelling sesquiterpene which spoils wine, produced by Penicillium expansum. The strains were identified by sequencing of the ITS and beta-tubulin regions. This study was based on a selection of four strains showing different levels of geosmin production, assessed by GC-MS/MS. The proteomics study revealed the differential abundance of 107 spots between the different strains; these were picked and submitted to MALDI-TOF-TOF MS analysis for identification. They belonged to the functional categories of protein metabolism, redox homeostasis, metabolic processes (glycolysis, ATP production), cell cycle and cell signalling pathways. From these data, an implication of oxidative stress in geosmin production may be hypothesized. Moreover, the differential abundance of some glycolytic enzymes may explain the different patterns of geosmin biosynthesis. This study provides data for the characterisation of the mechanism and the regulation of the production of this off-flavour, which are so far not described in filamentous fungi., Biological Significance: Green mould on grapes, caused by P. expansum may be at the origin of off-flavours in wine. These are characterized by earthy-mouldy smells and are due to the presence of the compound geosmin. This work aims at describing how geosmin is produced by P. expansum. This knowledge is of use for the research community on grapes for understanding why these off-flavours occasionally occur in vintages., (Copyright © 2013 Elsevier B.V. All rights reserved.)