High specificity generally characterizes mycorrhizal association in rare lady’s slipper orchids, genus Cypripedium. Mol Ecol

Department of Integrative Biology, University of California, 3060 Valley Life Sciences Building, #3140, Berkeley, California 94720, USA.
Molecular Ecology (Impact Factor: 6.49). 03/2005; 14(2):613-26. DOI: 10.1111/j.1365-294X.2005.02424.x
Source: PubMed


Lady's slipper orchids (Cypripedium spp.) are rare terrestrial plants that grow throughout the temperate Northern Hemisphere. Like all orchids, they require mycorrhizal fungi for germination and seedling nutrition. The nutritional relationships of adult Cypripedium mycorrhizae are unclear; however, Cypripedium distribution may be limited by mycorrhizal specificity, whether this specificity occurs only during the seedling stage or carries on into adulthood. We attempted to identify the primary mycorrhizal symbionts for 100 Cypripedium plants, and successfully did so with two Cypripedium calceolus, 10 Cypripedium californicum, six Cypripedium candidum, 16 Cypripedium fasciculatum, two Cypripedium guttatum, 12 Cypripedium montanum, and 11 Cypripedium parviflorum plants from a total of 44 populations in Europe and North America, yielding fungal nuclear large subunit and mitochondrial large subunit sequence and RFLP (restriction fragment length polymorphism) data for 59 plants. Because orchid mycorrhizal fungi are typically observed without fruiting structures, we assessed fungal identity through direct PCR (polymerase chain reaction) amplification of fungal genes from mycorrhizally colonized root tissue. Phylogenetic analysis revealed that the great majority of Cypripedium mycorrhizal fungi are members of narrow clades within the fungal family Tulasnellaceae. Rarely occurring root endophytes include members of the Sebacinaceae, Ceratobasidiaceae, and the ascomycetous genus, Phialophora. C. californicum was the only orchid species with apparently low specificity, as it associated with tulasnelloid, ceratobasidioid, and sebacinoid fungi in roughly equal proportion. Our results add support to the growing literature showing that high specificity is not limited to nonphotosynthetic plants, but also occurs in photosynthetic ones.

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Available from: Richard Shefferson, Oct 04, 2015
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    • "Although it has been hypothesized that mycorrhizal specificity is associated with rarity in orchids, the recent proliferation of molecular studies of orchid–fungal relationships is revealing that there is no clear trend between mycorrhizal specificity and the abundance and geographical range size of orchids (McCormick and Jacquemyn, 2014). For example, there are several instances in which rare orchids have been found to utilize multiple fungal species (Shefferson et al., 2005; Jacquemyn et al., 2011; Pandey et al., 2013). As seen in P. deformis, increasingly it is being shown that high mycorrhizal specificity can be associated with widespread host distribution . "
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    ABSTRACT: Although mycorrhizal associations are predominantly generalist, specialized mycorrhizal interactions have repeatedly evolved in Orchidaceae, suggesting a potential role in limiting the geographical range of orchid species. In particular, the Australian orchid flora is characterized by high mycorrhizal specialization and short-range endemism. This study investigates the mycorrhizae used by Pheladenia deformis, one of the few orchid species to occur across the Australian continent. Specifically, it examines whether P. deformis is widely distributed through using multiple fungi or a single widespread fungus, and if the fungi used by Australian orchids are widespread at the continental scale. Mycorrhizal fungi were isolated from P. deformis populations in eastern and western Australia. Germination trials using seed from western Australian populations were conducted to test if these fungi supported germination, regardless of the region in which they occurred. A phylogenetic analysis was undertaken using isolates from P. deformis and other Australian orchids that use the genus Sebacina to test for the occurrence of operational taxonomic units (OTUs) in eastern and western Australia. With the exception of one isolate, all fungi used by P. deformis belonged to a single fungal OTU of Sebacina. Fungal isolates from eastern and western Australia supported germination of P. deformis. A phylogenetic analysis of Australian Sebacina revealed that all of the OTUs that had been well sampled occurred on both sides of the continent. The use of a widespread fungal OTU in P. deformis enables a broad distribution despite high mycorrhizal specificity. The Sebacina OTUs that are used by a range of Australian orchids occur on both sides of the continent, demonstrating that the short-range endemism prevalent in the orchids is not driven by fungal species with narrow distributions. Alternatively, a combination of specific edaphic requirements and a high incidence of pollination by sexual deception may explain biogeographic patterns in southern Australian orchids. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email:
    Annals of Botany 06/2015; 116(3). DOI:10.1093/aob/mcv084 · 3.65 Impact Factor
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    • " n g i i n t h e Tu l a s n e l l a c e a e a n d Ceratobasidiaceae ( e . g . , cantharelloid clade ) has been previous - ly reported ( Otero et al . 2002 ; Ma et al . 2003 ; Suarez et al . 2006 ) . Certain photosynthetic orchids , even when sampled over a wide range , have a single dominant species of Rhizoctonia fungus ( McCormick et al . 2004 ; Shefferson et al . 2005 , 2010 ; Irwin et al . 2007 ) . However , fully mycoheterotrophic ( MH ) orchids , which are achlorophyllous and nutritionally dependent on their mycorrhizal fungi , can be colonized by several different ectomycorrhizal ( ECM ) fungi ( e . g . , Russulaceae and Thelephoraceae fungi ) ( Roy et al . 2009 ; Kennedy et al . 2011 ) as well a"
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    ABSTRACT: The medicinal effects and techniques for cultivating Anoectochilus formosanus are well-documented, but little is known about the mycorrhizal fungi associated with A. formosanus. Rhizoctonia (Thanatephorus) anastomosis group 6 (AG-6) was the most common species isolated from fungal pelotons in native A. formosanus and represented 67 % of the sample. Rhizoctonia (Ceratobasidium) AG-G, P, and R were also isolated and represent the first occurrence in the Orchidaceae. Isolates of AG-6, AG-R, and AG-P in clade I increased seed germination 44–91 % and promoted protocorm growth from phases III to VI compared to asymbiotic treatments and isolates of AG-G in clade II and Tulasnella species in clade III. All isolates in clades I to III formed fungal pelotons in tissue-cultured seedlings of A. formosanus, which exhibited significantly greater growth than nonmycorrhizal seedlings. An analysis of the relative effect of treatment ( \( {\widehat{p}}_i \) ) showed that the low level of colonization ( \( {\widehat{p}}_i = 0.30\hbox{--} 0.47 \) ) by isolates in clade I resulted in a significant increase in seedling growth compared to isolates in clades II (0.63–0.82) and III (0.63–0.75). There was also a negative correlation (r = −0.8801) with fresh plant weight and fungal colonization. Our results suggest that isolates in clade I may represent an important group associated with native populations of A. formosanus and can vary in their ability to establish a symbiotic association with A. formosanus. The results presented here are potentially useful for advancing research on the medicinal properties, production, and conservation of A. formosanus in diverse ecosystems.
    Mycorrhiza 01/2015; 25(6). DOI:10.1007/s00572-014-0616-1 · 3.46 Impact Factor
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    • "Moreover, the age of roots and intensity of fungal colonization may be linked. For example, in the photosynthetic orchid genus Cypripedium, fungal colonization differs by root age – only intermediate-aged roots are heavily colonized, while young and old roots are usually devoid of mycorrhizal colonization (Shefferson et al., 2005). Habitat type may have a strong impact on OrM fungal composition . "
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    ABSTRACT: Orchid mycorrhizal (OrM) symbionts play a key role in the growth of orchids, but the temporal variation and habitat partitioning of these fungi in roots and soil remain unclear.Temporal changes in root and rhizosphere fungal communities of Cypripedium calceolus, Neottia ovata and Orchis militaris were studied in meadow and forest habitats over the vegetation period by using 454 pyrosequencing of the full internal transcribed spacer (ITS) region.The community of typical OrM symbionts differed by plant species and habitats. The root fungal community of N. ovata changed significantly in time, but this was not observed in C. calceolus and O. militaris. The rhizosphere community included a low proportion of OrM symbionts that exhibited a slight temporal turnover in meadow habitats but not in forests. Habitat differences in OrM and all fungal associates are largely attributable to the greater proportion of ectomycorrhizal fungi in forests.Temporal changes in OrM fungal communities in roots of certain species indicate selection of suitable fungal species by plants. It remains to be elucidated whether these shifts depend on functional differences inside roots, seasonality, climate or succession.
    New Phytologist 12/2014; 205(4). DOI:10.1111/nph.13223 · 7.67 Impact Factor
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