Secondary metabolism and biotrophic lifestyle in the tomato pathogen Cladosporium fulvum.
Cladosporium fulvum is a biotrophic fungal pathogen that causes leaf mould of tomato. Analysis of its genome suggested a high potential for production of secondary metabolites (SM), which might be harmful to plants and animals. Here, we have analysed in detail the predicted SM gene clusters of C. fulvum employing phylogenetic and comparative genomic approaches. Expression of the SM core genes was measured by RT-qrtPCR and produced SMs were determined by LC-MS and NMR analyses. The genome of C. fulvum contains six gene clusters that are conserved in other fungal species, which have undergone rearrangements and gene losses associated with the presence of transposable elements. Although being a biotroph, C. fulvum has the potential to produce elsinochrome and cercosporin toxins. However, the corresponding core genes are not expressed during infection of tomato. Only two core genes, PKS6 and NPS9, show high expression in planta, but both are significantly down regulated during colonization of the mesophyll tissue. In vitro SM profiling detected only one major compound that was identified as cladofulvin. PKS6 is likely involved in the production of this pigment because it is the only core gene significantly expressed under these conditions. Cladofulvin does not cause necrosis on Solanaceae plants and does not show any antimicrobial activity. In contrast to other biotrophic fungi that have a reduced SM production capacity, our studies on C. fulvum suggest that down-regulation of SM biosynthetic pathways might represent another mechanism associated with a biotrophic lifestyle.
Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands ; Centre for Biosystems Genomics, Wageningen, The Netherlands.
Jérôme
J
Collemare
Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands.
Scott
S
Griffiths
Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands ; National Institute of Vegetable and Tea Science, Tsu, Japan.
Yuichiro
Y
Iida
Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands ; Department of Plant Pathology, Tarbiat Modares University, Tehran, Iran.
Mansoor
M
Karimi Jashni
Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands.
Evy
E
Battaglia
School of Chemistry, University of Bristol, Bristol, United Kingdom.
Russell J
RJ
Cox
Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands ; Centre for Biosystems Genomics, Wageningen, The Netherlands.
Pierre J G M
PJ
de Wit
D002963:Cladosporium / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D015169:Colony Count, Microbial; D004251:DNA Transposable Elements / Q000235:genetics; D015536:Down-Regulation / Q000235:genetics; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D015321:Gene Rearrangement; D005800:Genes, Fungal; D018551:Solanum lycopersicum / Q000382:microbiology*; D005810:Multigene Family; D010802:Phylogeny; D018515:Plant Leaves / Q000382:microbiology; D064210:Secondary Metabolism / Q000235:genetics; D026801:Synteny / Q000235:genetics
D004251:DNA Transposable Elements