Cladosporium research

The Cladosporium fulvum-tomato interaction is a model for pathosystems that obey the gene-for-gene concept.

This means that for every pathogen avirulence gene (Avr) there is a corresponding C. fulvum (Cf) tomato resistance gene that mediates recognition of the pathogen by the host. As a consequence of this recognition, a defense response is activated culminating in a hypersensitive response (a type of programmed cell death) that limits further growth of the fungal pathogen in tomato. Many Avr genes from C. fulvum, presently also called effector genes, have been identified, and for some of them the intrinsic function of the encoded protein has been assigned and studied in detail (Avr2, Avr4, Ecp2 and others). C. fulvum is a member of the Dothideomycetes, a class of fungi consisting of more than 3000 species. In recent years, the genomes of several of these species have been sequenced and based on sequence information it appears that C. fulvum is most related to Dothistroma septosporum (a pathogen of pine), Mycosphaerella populi (a pathogen of poplar), Mycosphaerella fijiensis (a pathogen of banana), and Mycosphaerella graminicola (a pathogen of wheat). Homologous effector genes have been identified in these species of which some appear species-specific, whereas others show a much broader occurrence in the fungal kingdom.

Our research focuses on the molecular communication between plants and these pathogens with a focus on the role of effectors in effector-triggered susceptibility (ETS) and in Cf-mediated effector-triggered immunity (ETI). On the plant side, we are interested in the perception of effectors and the participation of Cf- proteins in receptor complexes. We also study the molecular basis of evolution of effectors in C. fulvum and related fungal pathogens as a result of selection pressure imposed by resistance genes present in wild plant species and agricultural crops. We exploit the knowledge generated in these studies in resistance breeding.

Apart from effectors, some of the fungi mentioned above produce secondary metabolites that can be toxic to microbes, plants and mammals. We are interested in their biosynthesis, regulation, biological activities and molecular evolution in Dothideomycete fungi.

In our studies we depend on advanced methods and techniques including bioinformatics, comparative genomics, transcriptomics, proteomics and metabolomics to address our research questions that are subsequently backed-up by functional analyses involving fluorescence microscopy, transformation, gene disruption and pathogenicity assays. Below you will find more information on the ongoing research projects.

Left: Injection of Avr proteins. Right: Cf resistance genes trigger a hypersensitive response.
Left: Injection of Avr proteins. Right: Cf resistance genes trigger a hypersensitive response.