title: A major invasion of transposable elements accounts for the large size of the Blumeria graminis f.sp. tritici genome.
abstract: Powdery mildew of wheat (Triticum aestivum L.) is caused by the ascomycete fungus Blumeria graminis f.sp. tritici. Genomic approaches open new ways to study the biology of this obligate biotrophic pathogen. We started the analysis of the Bg tritici genome with the low-pass sequencing of its genome using the 454 technology and the construction of the first genomic bacterial artificial chromosome (BAC) library for this fungus. High-coverage contigs were assembled with the 454 reads. They allowed the characterization of 56 transposable elements and the establishment of the Blumeria repeat database. The BAC library contains 12,288 clones with an average insert size of 115 kb, which represents a maximum of 7.5-fold genome coverage. Sequencing of the BAC ends generated 12.6 Mb of random sequence representative of the genome. Analysis of BAC-end sequences revealed a massive invasion of transposable elements accounting for at least 85% of the genome. This explains the unusually large size of this genome which we estimate to be at least 174 Mb, based on a large-scale physical map constructed through the fingerprinting of the BAC library. Our study represents a crucial step in the perspective of the determination and study of the whole Bg tritici genome sequence.
authors.affiliation: Institute of Plant Biology, University of Zurich, Zollikerstrasse 107, Zurich, Switzerland.
authors.forename: Francis
authors.initials: F
authors.lastname: Parlange
authors.forename: Simone
authors.initials: S
authors.lastname: Oberhaensli
authors.forename: James
authors.initials: J
authors.lastname: Breen
authors.forename: Matthias
authors.initials: M
authors.lastname: Platzer
authors.forename: Stefan
authors.initials: S
authors.lastname: Taudien
authors.forename: Hana
authors.initials: H
authors.lastname: Simková
authors.forename: Thomas
authors.initials: T
authors.lastname: Wicker
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Doležel
authors.forename: Beat
authors.initials: B
authors.lastname: Keller
mesh_terms: D001203:Ascomycota / Q000235:genetics*; D002874:Chromosome Mapping; D022202:Chromosomes, Artificial, Bacterial; D004251:DNA Transposable Elements; D015723:Gene Library; D016681:Genome, Fungal; D059014:High-Throughput Nucleotide Sequencing; D010935:Plant Diseases / Q000382:microbiology; D012091:Repetitive Sequences, Nucleic Acid; D017422:Sequence Analysis, DNA
chemical_list: D004251:DNA Transposable Elements