title: Expression profiling of the wheat pathogen Zymoseptoria tritici reveals genomic patterns of transcription and host-specific regulatory programs.
abstract: Host specialization by pathogens requires a repertoire of virulence factors as well as fine-tuned regulation of gene expression. The fungal wheat pathogen Zymoseptoria tritici (synonym Mycosphaerella graminicola) is a powerful model system for the discovery of genetic elements that underlie virulence and host specialization. We transcriptionally profiled the early stages of Z. tritici infection of a compatible host (wheat) and a noncompatible host (Brachypodium distachyon). The results revealed infection regulatory programs common to both hosts and genes with striking wheat-specific expression, with many of the latter showing sequence signatures of positive selection along the Z. tritici lineage. Genes specifically regulated during infection of wheat populated two large clusters of coregulated genes that may represent candidate pathogenicity islands. On evolutionarily labile, repeat-rich accessory chromosomes (ACs), we identified hundreds of highly expressed genes with signatures of evolutionary constraint and putative biological function. Phylogenetic analyses suggested that gene duplication events on these ACs were rare and largely preceded the diversification of Zymoseptoria species. Together, our data highlight the likely relevance for fungal growth and virulence of hundreds of Z. tritici genes, deepening the annotation and functional inference of the genes of this model pathogen.
authors.affiliation: Max Planck Institute for Terrestrial Microbiology, Max Planck Research Group, Fungal Biodiversity, Marburg, Germany ronny.kellner@mpi-marburg.mpg.de.
authors.forename: Ronny
authors.initials: R
authors.lastname: Kellner
authors.affiliation: Max Planck Institute for Terrestrial Microbiology, Max Planck Research Group, Fungal Biodiversity, Marburg, Germany.
authors.forename: Amitava
authors.initials: A
authors.lastname: Bhattacharyya
authors.affiliation: Max Planck Institute for Terrestrial Microbiology, Max Planck Research Group, Fungal Biodiversity, Marburg, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Poppe
authors.affiliation: Department of Molecular and Cell Biology, University of California, BerkeleyPresent address: Graduate Program in Biological and Biomedical Sciences, Harvard Medical School, Boston, MA.
authors.forename: Tiffany Y
authors.initials: TY
authors.lastname: Hsu
authors.affiliation: Department of Molecular and Cell Biology, University of California, BerkeleyPresent address: Buck Institute for Research on Aging, Novato, CA.
authors.forename: Rachel B
authors.initials: RB
authors.lastname: Brem
authors.affiliation: Max Planck Institute for Terrestrial Microbiology, Max Planck Research Group, Fungal Biodiversity, Marburg, Germany.
authors.forename: Eva H
authors.initials: EH
authors.lastname: Stukenbrock
mesh_terms: D001203:Ascomycota / Q000235:genetics* / Q000502:physiology*; D015966:Gene Expression Regulation, Fungal; D054884:Host-Pathogen Interactions; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology*; D059467:Transcriptome; D014908:Triticum / Q000382:microbiology*
keywords: Mycosphaerella graminicola; RNA-seq; gene duplication; host adaptation; plant pathogenic fungi; supernumerary chromosomes