title: Fungal and plant gene expression in the Tulasnella calospora-Serapias vomeracea symbiosis provides clues about nitrogen pathways in orchid mycorrhizas.
abstract: Orchids are highly dependent on their mycorrhizal fungal partners for nutrient supply, especially during early developmental stages. In addition to organic carbon, nitrogen (N) is probably a major nutrient transferred to the plant because orchid tissues are highly N-enriched. We know almost nothing about the N form preferentially transferred to the plant or about the key molecular determinants required for N uptake and transfer. We identified, in the genome of the orchid mycorrhizal fungus Tulasnella calospora, two functional ammonium transporters and several amino acid transporters but found no evidence of a nitrate assimilation system, in agreement with the N preference of the free-living mycelium grown on different N sources. Differential expression in symbiosis of a repertoire of fungal and plant genes involved in the transport and metabolism of N compounds suggested that organic N may be the main form transferred to the orchid host and that ammonium is taken up by the intracellular fungus from the apoplatic symbiotic interface. This is the first study addressing the genetic determinants of N uptake and transport in orchid mycorrhizas, and provides a model for nutrient exchanges at the symbiotic interface, which may guide future experiments.
authors.affiliation: Department of Life Sciences and Systems Biology, University of Turin, 10125, Turin, Italy.|Institute for Sustainable Plant Protection (IPSP)-CNR, 10125, Turin, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: Fochi
authors.affiliation: Institute for Sustainable Plant Protection (IPSP)-CNR, 10125, Turin, Italy.
authors.forename: Walter
authors.identifier: 0000-0002-5382-3794
authors.initials: W
authors.lastname: Chitarra
authors.affiliation: Lab of Excellence ARBRE, INRA-Nancy and Lorraine University, Unité Mixte de Recherche 1136, 54280, Champenoux, France.
authors.forename: Annegret
authors.initials: A
authors.lastname: Kohler
authors.affiliation: Department of Life Sciences and Systems Biology, University of Turin, 10125, Turin, Italy.
authors.forename: Samuele
authors.initials: S
authors.lastname: Voyron
authors.affiliation: US Department of Energy, Joint Genome Institute, Walnut Creek, CA, 94598, USA.
authors.forename: Vasanth R
authors.initials: VR
authors.lastname: Singan
authors.affiliation: US Department of Energy, Joint Genome Institute, Walnut Creek, CA, 94598, USA.
authors.forename: Erika A
authors.initials: EA
authors.lastname: Lindquist
authors.affiliation: US Department of Energy, Joint Genome Institute, Walnut Creek, CA, 94598, USA.
authors.forename: Kerrie W
authors.initials: KW
authors.lastname: Barry
authors.affiliation: Department of Life Sciences and Systems Biology, University of Turin, 10125, Turin, Italy.|Institute for Sustainable Plant Protection (IPSP)-CNR, 10125, Turin, Italy.
authors.forename: Mariangela
authors.initials: M
authors.lastname: Girlanda
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: Lab of Excellence ARBRE, INRA-Nancy and Lorraine University, Unité Mixte de Recherche 1136, 54280, Champenoux, France.
authors.forename: Francis
authors.identifier: 0000-0002-4737-3715
authors.initials: F
authors.lastname: Martin
authors.affiliation: Institute for Sustainable Plant Protection (IPSP)-CNR, 10125, Turin, Italy.
authors.forename: Raffaella
authors.initials: R
authors.lastname: Balestrini
authors.affiliation: Department of Life Sciences and Systems Biology, University of Turin, 10125, Turin, Italy.|Institute for Sustainable Plant Protection (IPSP)-CNR, 10125, Turin, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Perotto
mesh_terms: D001487:Basidiomycota / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D018533:Biomass; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005800:Genes, Fungal; D017343:Genes, Plant; D005816:Genetic Complementation Test; D009154:Mutation / Q000235:genetics; D038821:Mycorrhizae / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D009584:Nitrogen / Q000378:metabolism* / Q000494:pharmacology; D029595:Orchidaceae / Q000187:drug effects / Q000235:genetics* / Q000382:microbiology*; D010802:Phylogeny; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000378:metabolism; D013559:Symbiosis / Q000187:drug effects / Q000235:genetics*
chemical_list: D005656:Fungal Proteins; D009584:Nitrogen
keywords: 
  Serapias
  ; 
  Tulasnella
  ; ammonium transporters; gene expression; nitrogen (N); orchid mycorrhiza; transcriptomics