Microorganisms, although being very diverse because they comprise prokaryotic organisms such as bacteria or eukaryotic organisms such as fungi, all share an essential exodigester function. The consequence is their essential need to have a secretome adapted to their environment. The selection pressure exerted by environmental constraints led to the emergence of species with varying complexity in terms of composition of their secretomes. This review on fungal secretomes highlights the extraordinary variability among these organisms, even within the same species, and hence the absolute necessity to fully characterize all their components in the aims of understanding the fundamental mechanisms responsible for secretome plasticity and developing applications notably toward a better control of diseases caused by these pathogens.

Although essential in many cellular processes, metals become toxic when they are present in excess and constitute a global environmental hazard. To overcome this stress, fungi have evolved several mechanisms at both intracellular and extracellular levels. In particular, fungi are well known for their ability to secrete a large panel of proteins. However, their role in the adaptation of fungi to metal toxicity has not yet been investigated. To address this question, here, the fungus Botrytis cinerea was challenged to copper, zinc, nickel or cadmium stress and secreted proteins were collected and separated by 2D-PAGE. One hundred and sixteen spots whose volume varied under at least one tested condition were observed on 2D gels. Densitometric analyses revealed that the secretome signature in response to cadmium was significantly different from those obtained with the other metals. Fifty-five of these 116 spots were associated with unique proteins and functional classification revealed that the production of oxidoreductases and cell-wall degrading enzymes was modified in response to metals. Promoter analysis disclosed that PacC/Rim101 sites were statistically over-represented in the upstream sequences of the 31 genes corresponding to the varying unique spots suggesting a possible link between pH regulation and metal response in B. cinerea.