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Zahn FE, Söll E, Chapin TK, Wang D, Gomes SIF, Hynson NA, Pausch J, Gebauer G. Novel insights into orchid mycorrhiza functioning from stable isotope signatures of fungal pelotons. New Phytol 2023. [PMID: 37343598 DOI: 10.1111/nph.18991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 04/29/2023] [Indexed: 06/23/2023]
Abstract
Stable isotope signatures of fungal sporocarps have been instrumental in identifying carbon gains of chlorophyllous orchids from a fungal source. Yet, not all mycorrhizal fungi produce macroscopic sporocarps and frequently fungi of different taxa occur in parallel in orchid roots. To overcome this obstacle, we investigated stable isotope signatures of fungal pelotons extracted from orchid roots and compared these data to the respective orchid and reference plant tissues. Anoectochilus sandvicensis and Epipactis palustris represented specialized or unspecialized rhizoctonia-associated orchids. Epipactis atrorubens and Epipactis leptochila are orchids considered ectomycorrhiza-associated with different preferences for Basidio- and Ascomycota. 13 C enrichment of rhizoctonia pelotons was minor compared with plant tissues and significantly lower than enrichments of pelotons from ectomycorrhizal Epipactis species. 15 N values of pelotons from E. leptochila and E. atrorubens showed similar patterns as known for respective sporocarps of ectomycorrhizal Ascomycota and Basidiomycota, however, with an offset towards lower 15 N enrichments and nitrogen concentrations. Our results suggest an explicit fungal nutrition source of orchids associated with ectomycorrhizal fungi, whereas the low 13 C enrichment in rhizoctonia-associated orchids and fungal pelotons hamper the detection of carbon gains from fungal partners. 15 N isotopic pattern of orchids further suggests a selective transfer of 15 N-enriched protein-nitrogen into orchids.
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Affiliation(s)
- Franziska E Zahn
- BayCEER - Laboratory of Isotope Biogeochemistry, University of Bayreuth, Bayreuth, 95440, Germany
| | - Erik Söll
- BayCEER - Laboratory of Isotope Biogeochemistry, University of Bayreuth, Bayreuth, 95440, Germany
| | - Thomas K Chapin
- Pacific Biosciences Research Center, University of Hawai'i at Mānoa, Honolulu, HI, 96822, USA
| | - Deyi Wang
- Naturalis Biodiversity Center, Leiden, 2332 AA, the Netherlands
| | - Sofia I F Gomes
- Institute of Biology, Leiden University, Leiden, 2333 BE, the Netherlands
| | - Nicole A Hynson
- Pacific Biosciences Research Center, University of Hawai'i at Mānoa, Honolulu, HI, 96822, USA
| | - Johanna Pausch
- Department of Agroecology, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, 95440, Germany
| | - Gerhard Gebauer
- BayCEER - Laboratory of Isotope Biogeochemistry, University of Bayreuth, Bayreuth, 95440, Germany
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Gomes SIF, Giesemann P, Klink S, Hunt C, Suetsugu K, Gebauer G. Stable isotope natural abundances of fungal hyphae extracted from the roots of arbuscular mycorrhizal mycoheterotrophs and rhizoctonia-associated orchids. New Phytol 2023. [PMID: 37343595 DOI: 10.1111/nph.18990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 04/29/2023] [Indexed: 06/23/2023]
Affiliation(s)
- Sofia I F Gomes
- Laboratory of Isotope Biogeochemistry, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, 95440, Germany
| | - Philipp Giesemann
- Laboratory of Isotope Biogeochemistry, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, 95440, Germany
| | - Saskia Klink
- Department of Agroecology, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Universitätsstraße 30, Bayreuth, 95440, Germany
| | - Colin Hunt
- Greenlife Industry Australia, PO Box 68, Kiama, NSW, 2533, Australia
| | - Kenji Suetsugu
- Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, 657-8501, Japan
- The Institute for Advanced Research, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, 657-8501, Japan
| | - Gerhard Gebauer
- Laboratory of Isotope Biogeochemistry, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, 95440, Germany
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Novotná A, Mennicken S, de Paula CCP, Vogt-Schilb H, Kotilínek M, Těšitelová T, Šmilauer P, Jersáková J. Variability in Nutrient Use by Orchid Mycorrhizal Fungi in Two Medium Types. J Fungi (Basel) 2023; 9:jof9010088. [PMID: 36675907 PMCID: PMC9865426 DOI: 10.3390/jof9010088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 12/28/2022] [Accepted: 01/03/2023] [Indexed: 01/07/2023] Open
Abstract
Orchid mycorrhizal fungi (OMF) from the rhizoctonia aggregate are generally considered to be soil saprotrophs, but their ability to utilize various nutrient sources has been studied in a limited number of isolates cultivated predominantly in liquid media, although rhizoctonia typically grow on the surface of solid substrates. Nine isolates representing the key OMF families (Ceratobasidiaceae, Tulasnellaceae and Serendipitaceae), sampled in Southern France and the Czech Republic, were tested for their ability to utilize carbon (C), nitrogen (N) and phosphorus (P) sources in vitro in both liquid and solid media. The isolates showed significant inter- and intra-familiar variability in nutrient utilization, most notably in N sources. Isolates produced generally larger amounts of dry biomass on solid medium than in liquid one, but some isolates showed no or limited biomass production on solid medium with particular nutrient sources. The largest amount of biomass was produced by isolates from the family Ceratobasidiaceae on most sources in both medium types. The biomass production of Tulasnellaceae isolates was affected by their phylogenetic relatedness on all sources and medium types. The ability of isolates to utilize particular nutrients in a liquid medium but not a solid one should be considered when optimizing solid media for symbiotic orchid seed germination and in understanding of OMF functional traits under in situ conditions.
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Affiliation(s)
- Alžběta Novotná
- Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, Branišovská 1760, 37005 České Budějovice, Czech Republic
| | - Sophie Mennicken
- Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, Branišovská 1760, 37005 České Budějovice, Czech Republic
| | - Caio C. Pires de Paula
- Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, Branišovská 1760, 37005 České Budějovice, Czech Republic
- Institute of Hydrobiology, Biology Centre CAS, Na Sádkách 702/7, 37005 České Budějovice, Czech Republic
| | - Hélène Vogt-Schilb
- Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, Branišovská 1760, 37005 České Budějovice, Czech Republic
- Centre d’Écologie Fonctionnelle et Évolutive, Centre National de la Recherche Scientifique, University of Montpellier, EPHE, IRD, 1919 Route de Mende, 34293 Montpellier, France
| | - Milan Kotilínek
- Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, Branišovská 1760, 37005 České Budějovice, Czech Republic
| | - Tamara Těšitelová
- Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, Branišovská 1760, 37005 České Budějovice, Czech Republic
| | - Petr Šmilauer
- Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, Branišovská 1760, 37005 České Budějovice, Czech Republic
| | - Jana Jersáková
- Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, Branišovská 1760, 37005 České Budějovice, Czech Republic
- Correspondence:
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Zahn FE, Lee YI, Gebauer G. Fungal association and root morphology shift stepwise during ontogenesis of orchid Cremastra appendiculata towards autotrophic nutrition. AoB Plants 2022; 14:plac021. [PMID: 35673361 PMCID: PMC9167560 DOI: 10.1093/aobpla/plac021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 05/03/2022] [Indexed: 06/15/2023]
Abstract
The chlorophyllous, terrestrial orchid Cremastra appendiculata from East Asia is unique concerning its fungal mycorrhiza partners. The initially mycoheterotrophic protocorms exploit rather specialized non-rhizoctonia saprotrophic Psathyrellaceae. Adult individuals of this orchid species are either linked to Psathyrellaceae being partially mycoheterotrophic or form mycorrhiza with fungi of the ubiquitous saprotrophic rhizoctonia group. This study provides new insights on nutrition mode, subterranean morphology and fungal partners across different life stages of C. appendiculata. We compared different development stages of C. appendiculata to surrounding autotrophic reference plants based on multi-element natural abundance stable isotope analyses (δ13C, δ15N, δ2H, δ18O) and total N concentrations. Site- and sampling-time-independent enrichment factors of stable isotopes were used to reveal trophic strategies. We determined mycorrhizal fungi of C. appendiculata protocorm, seedling and adult samples using high-throughput DNA sequencing. We identified saprotrophic non-rhizoctonia Psathyrellaceae as dominant mycorrhizal fungi in protocorm and seedling rhizomes. In contrast, the roots of seedlings and mature C. appendiculata were mainly colonized with fungi belonging to the polyphyletic assembly of rhizoctonia (Ceratobasidium, Thanatephorus and Serendipitaceae). Mature C. appendiculata did not differ in isotopic signature from autotrophic reference plants suggesting a fully autotrophic nutrition mode. Characteristic of orchid specimens entirely relying on fungal nutrition, C. appendiculata protocorms were enriched in 15N, 13C and 2H compared to reference plants. Seedlings showed an intermediate isotopic signature, underpinning the differences in the fungal community depending on their subterranean morphology. In contrast to the suggestion that C. appendiculata is a partially mycoheterotrophic orchid species, we provide novel evidence that mature C. appendiculata with rhizoctonia mycobionts can be entirely autotrophic. Besides an environmentally driven variability among populations, we suggest high within-individual flexibility in nutrition and mycobionts of C. appendiculata, which is subject to the ontogenetic development stage.
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Affiliation(s)
- Franziska E Zahn
- Laboratory of Isotope Biogeochemistry, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Universitätsstr. 30, 95440 Bayreuth, Germany
| | - Yung-I Lee
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan
- Institute of Ecology and Evolutionary Biology, National Taiwan University, Taipei 10617, Taiwan
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Suetsugu K, Yamato M, Matsubayashi J, Tayasu I. Comparative study of nutritional mode and mycorrhizal fungi in green and albino variants of Goodyera velutina, an orchid mainly utilizing saprotrophic rhizoctonia. Mol Ecol 2019; 28:4290-4299. [PMID: 31448451 DOI: 10.1111/mec.15213] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 07/05/2019] [Accepted: 07/22/2019] [Indexed: 01/30/2023]
Abstract
The majority of chlorophyllous orchids form mycorrhizal associations with so-called rhizoctonia fungi, a phylogenetically heterogeneous assemblage of predominantly saprotrophic fungi in Ceratobasidiaceae, Tulasnellaceae, and Serendipitaceae. It is still a matter of debate whether adult orchids mainly associated with rhizoctonia species are partially mycoheterotrophic. Here, we investigated the nutritional modes of green and albino variants of Goodyera velutina, an orchid species considered to be mainly associated with Ceratobasidium spp., by measuring their 13 C and 15 N abundances, and by molecular barcoding of their mycorrhizal fungi. Molecular analysis revealed that both green and albino variants of G. velutina harbored a similar range of mycobionts, mainly saprotrophic Ceratobasidium spp., Tulasnella spp., and ectomycorrhizal Russula spp. In addition, stable isotope analysis revealed that albino variants were significantly enriched in 13 C but not so greatly in 15 N, suggesting that saprotrophic Ceratobasidium spp. and Tulasnella spp. are their main carbon source. However, in green variants, 13 C levels were depleted and those of 15 N were indistinguishable from the co-occurring autotrophic plants. Therefore, we concluded that the albino G. velutina variants are fully mycoheterotrophic plants whose C derives mainly from saprotrophic rhizoctonia, while the green G. velutina variants are mainly autotrophic plants, at least at our study site, in spite of their additional associations with ectomycorrhizal fungi. This is the first report demonstrating that adult nonphotosynthetic albino variants can obtain their nutrition mainly from nonectomycorrhizal rhizoctonia.
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Affiliation(s)
- Kenji Suetsugu
- Department of Biology, Graduate School of Science, Kobe University, Kobe, Japan
| | | | - Jun Matsubayashi
- Department of Biogeochemistry, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan
| | - Ichiro Tayasu
- Research Institute for Humanity and Nature, Kyoto, Japan
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Oladzad A, Zitnick-Anderson K, Jain S, Simons K, Osorno JM, McClean PE, Pasche JS. Genotypes and Genomic Regions Associated With Rhizoctonia solani Resistance in Common Bean. Front Plant Sci 2019; 10:956. [PMID: 31396253 PMCID: PMC6667560 DOI: 10.3389/fpls.2019.00956] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 07/09/2019] [Indexed: 05/11/2023]
Abstract
Rhizoctonia solani Kühn (teleomorph Thanatephorus cucumeris) is an important root rot pathogen of common bean (Phaseolus vulgaris L.). To uncover genetic factors associated with resistance to the pathogen, the Andean (ADP; n = 273) and Middle American (MDP; n = 279) diversity panels, which represent much of the genetic diversity known in cultivated common bean, were screened in the greenhouse using R. solani anastomosis group 2-2. Repeatability of the assay was confirmed by the response of five control genotypes. The phenotypic data for both panels were normally distributed. The resistance responses of ∼10% of the ADP (n = 28) and ∼6% of the MDP (n = 18) genotypes were similar or higher than that of the resistant control line VAX 3. A genome-wide association study (GWAS) was performed using ∼200k single nucleotide polymorphisms to discover genomic regions associated with resistance in each panel, For GWAS, the raw phenotypic score, and polynomial and binary transformation of the scores, were individually used as the input data. A major QTL peak was observed on Pv02 in the ADP, while a major QTL was observed on Pv01 with the MDP. These regions were associated with clusters of TIR-NB_ARC-LRR (TNL) gene models encoding proteins similar to known disease resistance genes. Other QTL, unique to each panel, were mapped within or adjacent to a gene model or cluster of related genes associated with disease resistance. This is a first case study that provides evidence for major as well as minor genes involved in resistance to R. solani in common bean. This information will be useful to integrate more durable root rot resistance in common bean breeding programs and to study the genetic mechanisms associated with root diseases in this important societal legume.
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Affiliation(s)
- Atena Oladzad
- Department of Plant Sciences, North Dakota State University, Fargo, ND, United States
| | | | - Shalu Jain
- Department of Plant Pathology, North Dakota State University, Fargo, ND, United States
| | - Kristin Simons
- Department of Plant Sciences, North Dakota State University, Fargo, ND, United States
- Department of Plant Pathology, North Dakota State University, Fargo, ND, United States
| | - Juan M. Osorno
- Department of Plant Sciences, North Dakota State University, Fargo, ND, United States
| | - Phillip E. McClean
- Department of Plant Sciences, North Dakota State University, Fargo, ND, United States
| | - Julie S. Pasche
- Department of Plant Pathology, North Dakota State University, Fargo, ND, United States
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Swift S, Munroe S, Im C, Tipton L, Hynson NA. Remote tropical island colonization does not preclude symbiotic specialists: new evidence of mycorrhizal specificity across the geographic distribution of the Hawaiian endemic orchid Anoectochilus sandvicensis. Ann Bot 2019; 123:657-666. [PMID: 30380004 PMCID: PMC6417469 DOI: 10.1093/aob/mcy198] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 10/04/2018] [Indexed: 05/20/2023]
Abstract
BACKGROUND AND AIMS For symbiotic organisms, their colonization and spread across remote oceanic islands should favour generalists. Plants that form obligate symbiotic associations with microbes dominate island ecosystems, but the relationship between island inhabitance and symbiotic specificity is unclear, especially in the tropics. To fill this gap, we examined the mycorrhizal specificity of the Hawaiian endemic orchid Anoectochilus sandvicensis across multiple populations encompassing its entire geographic distribution. METHODS By molecular phylogenetic approaches we identified the mycorrhizal fungi associated with A. sandvicensis across its entire geographic distribution and determined the relationship of these fungi to others found elsewhere around the globe. With richness estimators, we assessed the mycorrhizal specificity of A. sandvicensis within and among islands. We then tested whether geographic proximity of orchid populations was a significant predictor for the presence of particular mycorrhizal fungi and their community composition. KEY RESULTS We found that each population of A. sandvicensis forms specific associations with one of three fungi in the genus Ceratobasidium and that the closest relatives of these fungi are globally widespread. Based on diversity indices, A. sandvicensis populations were estimated to partner with one to four mycorrhizal taxa with an estimated total of four compatible mycorrhizal fungi across its entire distribution. However, the geographic proximity of orchid populations was not a significant predictor of mycorrhizal fungal community composition. CONCLUSIONS Our findings indicate that the colonization and survival of plant species on even the most remote oceanic islands is not restricted to symbiotic generalists, and that partnering with few, but cosmopolitan microbial symbionts is an alternative means for successful island establishment. We suggest that the spatial distribution and abundance of symbionts in addition to island age, size and isolation should also be taken into consideration for predictions of island biodiversity.
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Affiliation(s)
- Sean Swift
- Department of Botany, University of Hawaii Manoa, Honolulu, HI, USA
| | - Sherilyn Munroe
- Department of Botany, University of Hawaii Manoa, Honolulu, HI, USA
| | - Chaewon Im
- John A. Burns School of Medicine, University of Hawaii Manoa, Honolulu, HI, USA
| | - Laura Tipton
- Department of Botany, University of Hawaii Manoa, Honolulu, HI, USA
| | - Nicole A Hynson
- Pacific Biosciences Research Center, University of Hawaii Manoa, Honolulu, HI, USA
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Jacquemyn H, Waud M, Brys R, Lallemand F, Courty PE, Robionek A, Selosse MA. Mycorrhizal Associations and Trophic Modes in Coexisting Orchids: An Ecological Continuum between Auto- and Mixotrophy. Front Plant Sci 2017; 8:1497. [PMID: 28912791 PMCID: PMC5583604 DOI: 10.3389/fpls.2017.01497] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2017] [Accepted: 08/14/2017] [Indexed: 05/03/2023]
Abstract
Two distinct nutritional syndromes have been described in temperate green orchids. Most orchids form mycorrhizas with rhizoctonia fungi and are considered autotrophic. Some orchids, however, associate with fungi that simultaneously form ectomycorrhizas with surrounding trees and derive their carbon from these fungi. This evolutionarily derived condition has been called mixotrophy or partial mycoheterotrophy and is characterized by 13C enrichment and high N content. Although it has been suggested that the two major nutritional syndromes are clearly distinct and tightly linked to the composition of mycorrhizal communities, recent studies have challenged this assumption. Here, we investigated whether mycorrhizal communities and nutritional syndromes differed between seven green orchid species that co-occur under similar ecological conditions (coastal dune slacks). Our results showed that mycorrhizal communities differed significantly between orchid species. Rhizoctonia fungi dominated in Dactylorhiza sp., Herminium monorchis, and Epipactis palustris, which were autotrophic based on 13C and N content. Conversely, Liparis loeselii and Epipactis neerlandica associated primarily with ectomycorrhizal fungi but surprisingly, 13C and N content supported mixotrophy only in E. neerlandica. This, together with the finding of some ectomycorrhizal fungi in rhizoctonia-associated orchids, suggests that there exists an ecological continuum between the two syndromes. The presence of a large number of indicator species associating with individual orchid species further confirms previous findings that mycorrhizal fungi may be important factors driving niche-partitioning in terrestrial orchids and therefore contribute to orchid coexistence.
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Affiliation(s)
- Hans Jacquemyn
- Plant Conservation and Population Biology, Department of Biology, KU LeuvenLeuven, Belgium
| | - Michael Waud
- Plant Conservation and Population Biology, Department of Biology, KU LeuvenLeuven, Belgium
| | - Rein Brys
- Research Institute for Forest and NatureGeraardsbergen, Belgium
| | - Félix Lallemand
- Institut de Systématique, Évolution, Biodiversité, UMR 7205, CNRS, MNHN, UPMC, EPHE, Muséum National d’Histoire Naturelle, Sorbonne UniversitésParis, France
| | | | - Alicja Robionek
- The Laboratory of Freshwater Ecology, Department of Plant Ecology, University of GdańskGdańsk, Poland
- Department of Plant Taxonomy and Nature Conservation, University of GdańskGdańsk, Poland
| | - Marc-André Selosse
- Institut de Systématique, Évolution, Biodiversité, UMR 7205, CNRS, MNHN, UPMC, EPHE, Muséum National d’Histoire Naturelle, Sorbonne UniversitésParis, France
- Department of Plant Taxonomy and Nature Conservation, University of GdańskGdańsk, Poland
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Hynson NA. The carbon and nitrogen ecophysiologies of two endemic tropical orchids mirrors those of their temperate relatives and the local environment. R Soc Open Sci 2016; 3:160427. [PMID: 28018622 PMCID: PMC5180120 DOI: 10.1098/rsos.160427] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 09/08/2016] [Indexed: 05/23/2023]
Abstract
Orchids are one of the most widely distributed plant families. However, current research on the ecophysiology of terrestrial orchids is biased towards temperate species. Thus, it is currently unknown whether tropical terrestrial orchids belong to similar trophic guilds as their temperate relatives. To examine the ecophysiologies of two tropical terrestrial orchids, I analysed the carbon and nitrogen stable isotope compositions and nitrogen concentrations of the Hawaiian endemics Anoectochilus sandvicensis and Liparis hawaiensis. I compared these values with those of surrounding vegetation and their temperate relatives. I found that A. sandvicensis was consistently enriched in the heavy isotope of nitrogen (15N) and had higher nitrogen (N) concentrations than surrounding vegetation, and these values were even higher than those of its temperate relatives. Carbon stable isotope composition among populations of A. sandvicensis varied by island. These results point to local environment and evolutionary history determining the ecophysiology of this species. Whereas L.hawaiensis was also enriched in 15N and had on average higher N concentrations than surrounding vegetation, these values were not significantly different from temperate relatives, indicating that evolutionary history may be a stronger predictor of this orchid species' ecophysiology than environment. I suggest that both Hawaiian species are potentially partially mycoheterotrophic.
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Affiliation(s)
- Nicole A. Hynson
- Department of Botany, University of Hawaii Manoa, 3190 Maile Way Room 101, Honolulu, HI 96822, USA
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Stöckel M, Těšitelová T, Jersáková J, Bidartondo MI, Gebauer G. Carbon and nitrogen gain during the growth of orchid seedlings in nature. New Phytol 2014; 202:606-615. [PMID: 24444001 DOI: 10.1111/nph.12688] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 12/17/2013] [Indexed: 05/12/2023]
Abstract
For germination and establishment, orchids depend on carbon (C) and nutrients supplied by mycorrhizal fungi. As adults, the majority of orchids then appear to become autotrophic. To compare the proportional C and nitrogen (N) gain from fungi in mycoheterotrophic seedlings and in adults, here we examined in the field C and N stable isotope compositions in seedlings and adults of orchids associated with ectomycorrhizal and saprotrophic fungi. Using a new highly sensitive approach, we measured the isotope compositions of seedlings and adults of four orchid species belonging to different functional groups: fully and partially mycoheterotrophic orchids associated with narrow or broad sets of ectomycorrhizal fungi, and two adult putatively autotrophic orchids associated exclusively with saprotrophic fungi. Seedlings of orchids associated with ectomycorrhizal fungi were enriched in (13) C and (15) N similarly to fully mycoheterotrophic adults. Seedlings of saprotroph-associated orchids were also enriched in (13) C and (15) N, but unexpectedly their enrichment was significantly lower, making them hardly distinguishable from their respective adult stages and neighbouring autotrophic plants. We conclude that partial mycoheterotrophy among saprotroph-associated orchids cannot be identified unequivocally based on C and N isotope compositions alone. Thus, partial mycoheterotrophy may be much more widely distributed among orchids than hitherto assumed.
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Affiliation(s)
- Marcus Stöckel
- Laboratory of Isotope Biogeochemistry, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, 95440, Bayreuth, Germany
| | - Tamara Těšitelová
- Faculty of Science, University of South Bohemia, Branišovská 31, 370 05, České Budějovice, Czech Republic
| | - Jana Jersáková
- Faculty of Science, University of South Bohemia, Branišovská 31, 370 05, České Budějovice, Czech Republic
| | | | - Gerhard Gebauer
- Laboratory of Isotope Biogeochemistry, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, 95440, Bayreuth, Germany
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Abstract
The ultrastructure of the pore cap in ten multinucleate rhizoctonias, endophytes of non-orchids and of Microtis (Orchidaceae), was compared with that in isolates of four Sebacina species. The pore cap in all the rhizoctonias was an imperforate, disc-like structure, Slightly smaller in diameter than the flange forming the septal pore canal. The cap was formed by two Bat lamellae continuous with, but more electron-dense than, the membranes of the endoplasmic reticulum. The lamellae enclosed a lumen containing a deposit of electron-dense material. The pore cap in the rhizoctonias was indistinguishable from that in an isolate of Sebacina vermifera Oberwinkler. In contrast, the pore caps in isolates of S. calcea (Pers.: Fr.) Bres., S. umbrina Rogers and S. grisea (Pets.: Fr.) Bres., which were also imperforate and contained a band of electron dense material, were strongly dome-shaped and extended from one side of the flange to the other.
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Affiliation(s)
- P G Williams
- Biological and Chemical Research Institute, New South Wales Department of Agriculture, Rydalmere, NSW 2116, Australia
| | - E Thilo
- Biological and Chemical Research Institute, New South Wales Department of Agriculture, Rydalmere, NSW 2116, Australia
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