title: Photosynthetic Mediterranean meadow orchids feature partial mycoheterotrophy and specific mycorrhizal associations.
abstract: OBJECTIVE
  We investigated whether four widespread, photosynthetic Mediterranean meadow orchids (Ophrys fuciflora, Anacamptis laxiflora, Orchis purpurea, and Serapias vomeracea) had either nutritional dependency on mycobionts or mycorrhizal fungal specificity. Nonphotosynthetic orchids generally engage in highly specific interactions with fungal symbionts that provide them with organic carbon. By contrast, fully photosynthetic orchids in sunny, meadow habitats have been considered to lack mycorrhizal specificity.
  
  
  METHODS
  We performed both culture-dependent and culture-independent ITS sequence analysis to identify fungi from orchid roots. By analyzing stable isotope ((13)C and (15)N) natural abundances, we also determined the degree of autotrophy and mycoheterotrophy in the four orchid species.
  
  
  RESULTS
  Phylogenetic and multivariate comparisons indicated that Or. purpurea and Oph. fuciflora featured lower fungal diversity and more specific mycobiont spectra than A. laxiflora and S. vomeracea. All orchid species were significantly enriched in (15)N compared with neighboring non-orchid plants. Orchis purpurea had the most pronounced N gain from fungi and differed from the other orchids in also obtaining C from fungi.
  
  
  CONCLUSIONS
  These results indicated that even in sunny Mediterranean meadows, orchids may be mycoheterotrophic, with correlated mycorrhizal fungal specificity.
authors.affiliation: Dipartimento di Biologia Vegetale dell'Università di Torino e Istituto per la Protezione delle Piante del CNR, Viale Mattioli 25 10125 Torino, Italy. mariangela.girlanda@unito.it
authors.forename: Mariangela
authors.initials: M
authors.lastname: Girlanda
authors.forename: Rossana
authors.initials: R
authors.lastname: Segreto
authors.forename: Donata
authors.initials: D
authors.lastname: Cafasso
authors.forename: Heiko Tobias
authors.initials: HT
authors.lastname: Liebel
authors.forename: Michele
authors.initials: M
authors.lastname: Rodda
authors.forename: Enrico
authors.initials: E
authors.lastname: Ercole
authors.forename: Salvatore
authors.initials: S
authors.lastname: Cozzolino
authors.forename: Gerhard
authors.initials: G
authors.lastname: Gebauer
authors.forename: Silvia
authors.initials: S
authors.lastname: Perotto
mesh_terms: D001499:Bayes Theorem; D002244:Carbon / Q000378:metabolism; D002247:Carbon Isotopes; D015169:Colony Count, Microbial; D016002:Discriminant Analysis; D017753:Ecosystem; D060026:Endophytes / Q000502:physiology; D052836:Heterotrophic Processes / Q000502:physiology*; D019083:Mediterranean Region; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D038821:Mycorrhizae / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D009584:Nitrogen / Q000378:metabolism; D009587:Nitrogen Isotopes; D029595:Orchidaceae / Q000166:cytology / Q000382:microbiology* / Q000502:physiology*; D010788:Photosynthesis / Q000502:physiology*; D010802:Phylogeny; D012232:Rhizoctonia / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D016415:Sequence Alignment; D013045:Species Specificity
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D002244:Carbon; D009584:Nitrogen