title: Genome sequencing provides insight into the reproductive biology, nutritional mode and ploidy of the fern pathogen Mixia osmundae.
abstract: Mixia osmundae (Basidiomycota, Pucciniomycotina) represents a monotypic class containing an unusual fern pathogen with incompletely understood biology. We sequenced and analyzed the genome of M. osmundae, focusing on genes that may provide some insight into its mode of pathogenicity and reproductive biology. Mixia osmundae has the smallest plant pathogenic basidiomycete genome sequenced to date, at 13.6 Mb, with very few repeats, high gene density, and relatively few significant gene family gains. The genome shows that the yeast state of M. osmundae is haploid and the lack of segregation of mating genes suggests that the spores produced on Osmunda spp. fronds are probably asexual. However, our finding of a complete complement of mating and meiosis genes suggests the capacity to undergo sexual reproduction. Analyses of carbohydrate active enzymes suggest that this fungus is a biotroph with the ability to break down several plant cell wall components. Analyses of publicly available sequence data show that other Mixia members may exist on other plant hosts and with a broader distribution than previously known.
authors.affiliation: Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA.
authors.forename: Merje
authors.initials: M
authors.lastname: Toome
authors.affiliation: US Department of Energy Joint Genome Institute, Walnut Creek, CA, 94598, USA.
authors.forename: Robin A
authors.initials: RA
authors.lastname: Ohm
authors.affiliation: US Department of Energy Joint Genome Institute, Walnut Creek, CA, 94598, USA.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Riley
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
authors.forename: Timothy Y
authors.initials: TY
authors.lastname: James
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Lazarus
authors.affiliation: Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille University, CNRS UMR 7257, 13288, Marseille, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Henrissat
authors.affiliation: Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA, 70803, USA.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Albu
authors.affiliation: Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Boyd
authors.affiliation: US Department of Energy Joint Genome Institute, Walnut Creek, CA, 94598, USA.
authors.forename: Julianna
authors.initials: J
authors.lastname: Chow
authors.affiliation: US Department of Energy Joint Genome Institute, Walnut Creek, CA, 94598, USA.
authors.forename: Alicia
authors.initials: A
authors.lastname: Clum
authors.affiliation: Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA, 70803, USA.
authors.forename: Gregory
authors.initials: G
authors.lastname: Heller
authors.affiliation: US Department of Energy Joint Genome Institute, Walnut Creek, CA, 94598, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Lipzen
authors.affiliation: US Department of Energy Joint Genome Institute, Walnut Creek, CA, 94598, USA.
authors.forename: Matt
authors.initials: M
authors.lastname: Nolan
authors.affiliation: US Department of Energy Joint Genome Institute, Walnut Creek, CA, 94598, USA.
authors.forename: Laura
authors.initials: L
authors.lastname: Sandor
authors.affiliation: US Department of Energy Joint Genome Institute, Walnut Creek, CA, 94598, USA.
authors.forename: Natasha
authors.initials: N
authors.lastname: Zvenigorodsky
authors.affiliation: US Department of Energy Joint Genome Institute, Walnut Creek, CA, 94598, USA.
authors.forename: Igor V
authors.initials: IV
authors.lastname: Grigoriev
authors.affiliation: Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, USA.
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Spatafora
authors.affiliation: Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA.
authors.forename: M Catherine
authors.initials: MC
authors.lastname: Aime
mesh_terms: D001487:Basidiomycota / Q000235:genetics* / Q000472:pathogenicity; D050260:Carbohydrate Metabolism; D002473:Cell Wall; D004271:DNA, Fungal / Q000032:analysis*; D029624:Ferns / Q000382:microbiology*; D005800:Genes, Fungal; D016681:Genome, Fungal; D006238:Haploidy; D008540:Meiosis; D010935:Plant Diseases / Q000382:microbiology*; D012098:Reproduction; D012100:Reproduction, Asexual; D013172:Spores, Fungal; D015003:Yeasts
chemical_list: D004271:DNA, Fungal
keywords: CAZy; Mixiomycetes; Osmunda spp.; biotrophic fungi; fungal genomics; sporogenesis