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Habitat-driven variation in mycorrhizal communities in the terrestrial orchid genus Dactylorhiza

View Article: PubMed Central - PubMed

ABSTRACT

Orchid species are critically dependent on mycorrhizal fungi for completion of their life cycle, particularly during the early stages of their development when nutritional resources are scarce. As such, orchid mycorrhizal fungi play an important role in the population dynamics, abundance, and spatial distribution of orchid species. However, less is known about the ecology and distribution of orchid mycorrhizal fungi. In this study, we used 454 amplicon pyrosequencing to investigate ecological and geographic variation in mycorrhizal associations in fourteen species of the orchid genus Dactylorhiza. More specifically, we tested the hypothesis that variation in orchid mycorrhizal communities resulted primarily from differences in habitat conditions where the species were growing. The results showed that all investigated Dactylorhiza species associated with a large number of fungal OTUs, the majority belonging to the Tulasnellaceae, Ceratobasidiaceae and Sebacinales. Mycorrhizal specificity was low, but significant variation in mycorrhizal community composition was observed between species inhabiting different ecological habitats. Although several fungi had a broad geographic distribution, Species Indicator Analysis revealed some fungi that were characteristic for specific habitats. Overall, these results indicate that orchid mycorrhizal fungi may have a broad geographic distribution, but that their occurrence is bounded by specific habitat conditions.

No MeSH data available.


Matrix representation of the studied orchid mycorrhizal network encompassing fourteen Dactylorhiza species (rows) and putative orchid mycorrhizal operational taxonomic units (OTUs) (columns).Different colors represent different modules. Red cells are species links gluing the six modules together into a coherent network, and non-red cells are links within modules.
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f3: Matrix representation of the studied orchid mycorrhizal network encompassing fourteen Dactylorhiza species (rows) and putative orchid mycorrhizal operational taxonomic units (OTUs) (columns).Different colors represent different modules. Red cells are species links gluing the six modules together into a coherent network, and non-red cells are links within modules.

Mentions: The modularity analysis showed that the network of interactions was significantly modular (Mobs = 0.4737, Mrandom = 0.4461 ± 0.0084, P < 0.001) and that six modules were identified (Fig. 3). The largest module consisted of four species and contained the four sampled species typically occurring in Mediterranean habitats (D. markusii, D. insularis, D. romana and D. sambucina) (Fig. 3). D. praetermissa and D. incarnata formed another module and represent species that were mainly sampled in coastal habitats. The module of D. maculata, D. sphagnicola and D. viridis showed less links to other modules. Finally, D. alpestris formed a module that consisted of a single species (Fig. 3). Broadly speaking, these modules can also be brought back to the habitats from which the orchids were sampled, but not to their ploidy level.


Habitat-driven variation in mycorrhizal communities in the terrestrial orchid genus Dactylorhiza
Matrix representation of the studied orchid mycorrhizal network encompassing fourteen Dactylorhiza species (rows) and putative orchid mycorrhizal operational taxonomic units (OTUs) (columns).Different colors represent different modules. Red cells are species links gluing the six modules together into a coherent network, and non-red cells are links within modules.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5121631&req=5

f3: Matrix representation of the studied orchid mycorrhizal network encompassing fourteen Dactylorhiza species (rows) and putative orchid mycorrhizal operational taxonomic units (OTUs) (columns).Different colors represent different modules. Red cells are species links gluing the six modules together into a coherent network, and non-red cells are links within modules.
Mentions: The modularity analysis showed that the network of interactions was significantly modular (Mobs = 0.4737, Mrandom = 0.4461 ± 0.0084, P < 0.001) and that six modules were identified (Fig. 3). The largest module consisted of four species and contained the four sampled species typically occurring in Mediterranean habitats (D. markusii, D. insularis, D. romana and D. sambucina) (Fig. 3). D. praetermissa and D. incarnata formed another module and represent species that were mainly sampled in coastal habitats. The module of D. maculata, D. sphagnicola and D. viridis showed less links to other modules. Finally, D. alpestris formed a module that consisted of a single species (Fig. 3). Broadly speaking, these modules can also be brought back to the habitats from which the orchids were sampled, but not to their ploidy level.

View Article: PubMed Central - PubMed

ABSTRACT

Orchid species are critically dependent on mycorrhizal fungi for completion of their life cycle, particularly during the early stages of their development when nutritional resources are scarce. As such, orchid mycorrhizal fungi play an important role in the population dynamics, abundance, and spatial distribution of orchid species. However, less is known about the ecology and distribution of orchid mycorrhizal fungi. In this study, we used 454 amplicon pyrosequencing to investigate ecological and geographic variation in mycorrhizal associations in fourteen species of the orchid genus Dactylorhiza. More specifically, we tested the hypothesis that variation in orchid mycorrhizal communities resulted primarily from differences in habitat conditions where the species were growing. The results showed that all investigated Dactylorhiza species associated with a large number of fungal OTUs, the majority belonging to the Tulasnellaceae, Ceratobasidiaceae and Sebacinales. Mycorrhizal specificity was low, but significant variation in mycorrhizal community composition was observed between species inhabiting different ecological habitats. Although several fungi had a broad geographic distribution, Species Indicator Analysis revealed some fungi that were characteristic for specific habitats. Overall, these results indicate that orchid mycorrhizal fungi may have a broad geographic distribution, but that their occurrence is bounded by specific habitat conditions.

No MeSH data available.