Symbiotic germination capability of four Epipactis species (Orchidaceae) is broader than expected from adult ecology.
OBJECTIVE
Both abiotic and biotic factors shape species distributions. Orchids produce minute seeds with few nutrient reserves, thus requiring mycorrhizal fungi for germination. Therefore, both environmental conditions and mycorrhizal fungi distribution affect their germination success, but these ecological requirements and their congruence with habitat preferences of adults remain poorly understood. We investigated the importance of these factors during germination in four forest orchid species of the genus Epipactis.


METHODS
We sowed seeds of three habitat specialists and one generalist in different forest types at sites harboring adults of at least one of these ecologically diverging species. We analyzed germination pattern and identified mycorrhizal fungi of both seedlings and adults.


RESULTS
Habitat conditions had little influence on germination pattern as seedlings grew in more habitats than expected from the adults' ecology. Ectomycorrhizal fungi availability did not limit germination. Suitable mycorrhizal fungi, mostly pezizalean ascomycetes, were recruited in various forest types, though the fungal communities differed according to habitat type. Finally, orchids with divergent ecological preferences shared similar mycorrhizal fungi.


CONCLUSIONS
Limited adult distribution contrasted with successful seed germination at diverse sites and indicates existence of niche differentiation between adults and seedlings. Ecological specialization may thus be determined by factors other than mycorrhizal fungi that act later in the ontogeny, perhaps during the transition to above-ground development.
University of South Bohemia, Branišovská 31, 370 05 Ceské Budejovice, Czech Republic. tamara.malinova@centrum.cz
Tamara
T
Tĕšitelová
Jakub
J
Tĕšitel
Jana
J
Jersáková
Gabriela
G
RÍhová
Marc-André
MA
Selosse
D001203:Ascomycota / Q000145:classification / Q000235:genetics / Q000502:physiology; D018153:Czech Republic; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D017753:Ecosystem; D014644:Genetic Variation; D005843:Geography; D018525:Germination; D054884:Host-Pathogen Interactions; D008969:Molecular Sequence Data; D038821:Mycorrhizae / Q000145:classification / Q000235:genetics / Q000502:physiology; D029595:Orchidaceae / Q000145:classification / Q000254:growth & development* / Q000382:microbiology; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012339:RNA, Ribosomal, 28S / Q000235:genetics; D012340:RNA, Ribosomal, 5.8S / Q000235:genetics; D036226:Seedlings / Q000254:growth & development / Q000382:microbiology; D012639:Seeds / Q000254:growth & development* / Q000382:microbiology; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D013559:Symbiosis
D004271:DNA, Fungal; D021903:DNA, Ribosomal Spacer; D012337:RNA, Ribosomal, 18S; D012339:RNA, Ribosomal, 28S; D012340:RNA, Ribosomal, 5.8S