title: Large-scale gene discovery in the septoria tritici blotch fungus Mycosphaerella graminicola with a focus on in planta expression.
abstract: The foliar disease septoria tritici blotch, caused by the fungus Mycosphaerella graminicola, is currently the most important wheat disease in Europe. Gene expression was examined under highly different conditions, using 10 expressed sequence tag libraries generated from M. graminicola isolate IPO323 using seven in vitro and three in planta growth conditions. To identify fungal clones in the interaction libraries, we developed a selection method based on hybridization with the entire genomic DNA of M. graminicola, to selectively enrich these libraries for fungal genes. Assembly of the 27,007 expressed sequence tags resulted in 9,190 unigenes, representing 5.2 Mb of the estimated 39-Mb genome size of M. graminicola. All libraries contributed significantly to the number of unigenes, especially the in planta libraries representing different stages of pathogenesis, which covered 15% of the library-specific unigenes. Even under presymptomatic conditions (5 days postinoculation), when fungal biomass is less than 5%, this method enabled us to efficiently capture fungal genes expressed during pathogenesis. Many of these genes were uniquely expressed in planta, indicating that in planta gene expression significantly differed from in vitro expression. Examples of gene discovery included a number of cell wall-degrading enzymes, a broad set of genes involved in signal transduction (n=11) and a range of ATP-binding cassette (n=20) and major facilitator superfamily transporter genes (n=12) potentially involved in protection against antifungal compounds or the secretion of pathogenicity factors. In addition, evidence is provided for a mycovirus in M. graminicola that is highly expressed under various stress conditions, in particular, under nitrogen starvation. Our analyses provide a unique window on in vitro and in planta gene expression of M. graminicola.
authors.affiliation: Plant Research International B.V., Wageningen, The Netherlands. gert.kema@wur.nl
authors.forename: Gert H J
authors.initials: GH
authors.lastname: Kema
authors.forename: Theo A J
authors.initials: TA
authors.lastname: van der Lee
authors.forename: Odette
authors.initials: O
authors.lastname: Mendes
authors.forename: Els C P
authors.initials: EC
authors.lastname: Verstappen
authors.forename: René Klein
authors.initials: RK
authors.lastname: Lankhorst
authors.forename: Hans
authors.initials: H
authors.lastname: Sandbrink
authors.forename: Ate
authors.initials: A
authors.lastname: van der Burgt
authors.forename: Lute-Harm
authors.initials: LH
authors.lastname: Zwiers
authors.forename: Michael
authors.initials: M
authors.lastname: Csukai
authors.forename: Cees
authors.initials: C
authors.lastname: Waalwijk
mesh_terms: D001203:Ascomycota / Q000235:genetics* / Q000254:growth & development; D016000:Cluster Analysis; D020224:Expressed Sequence Tags; D005656:Fungal Proteins / Q000145:classification / Q000235:genetics; D015966:Gene Expression Regulation, Fungal; D015723:Gene Library; D005800:Genes, Fungal / Q000235:genetics; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D014908:Triticum / Q000382:microbiology*
chemical_list: D005656:Fungal Proteins