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Tian F, Wang J, Ding F, Wang L, Yang Y, Bai X, Tan C, Liao X. Comparative transcriptomics and proteomics analysis of the symbiotic germination of Paphiopedilum barbigerum with Epulorhiza sp. FQXY019. Front Microbiol 2024; 15:1358137. [PMID: 38562471 PMCID: PMC10982344 DOI: 10.3389/fmicb.2024.1358137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 03/06/2024] [Indexed: 04/04/2024] Open
Abstract
Introduction Paphiopedilum barbigerum is currently the rarest and most endangered species of orchids in China and has significant ornamental value. The mature seeds of P. barbigerum are difficult to germinate owing to the absence of an endosperm and are highly dependent on mycorrhizal fungi for germination and subsequent development. However, little is known about the regulation mechanisms of symbiosis and symbiotic germination of P. barbigerum seeds. Methods Herein, transcriptomics and proteomics were used to explore the changes in the P. barbigerum seeds after inoculation with (FQXY019 treatment group) or without (control group) Epulorhiza sp. FQXY019 at 90 days after germination. Results Transcriptome sequencing revealed that a total of 10,961 differentially expressed genes (DEGs; 2,599 upregulated and 8,402 downregulated) were identified in the control and FQXY019 treatment groups. These DEGs were mainly involved in carbohydrate, fatty acid, and amino acid metabolism. Furthermore, the expression levels of candidate DEGs related to nodulin, Ca2+ signaling, and plant lectins were significantly affected in P. barbigerum in the FQXY019 treatment groups. Subsequently, tandem mass tag-based quantitative proteomics was performed to recognize the differentially expressed proteins (DEPs), and a total of 537 DEPs (220 upregulated and 317 downregulated) were identified that were enriched in processes including photosynthesis, photosynthesis-antenna proteins, and fatty acid biosynthesis and metabolism. Discussion This study provides novel insight on the mechanisms underlying the in vitro seed germination and protocorm development of P. barbigerum by using a compatible fungal symbiont and will benefit the reintroduction and mycorrhizal symbiotic germination of endangered orchids.
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Affiliation(s)
- Fan Tian
- Guizhou Academy of Forestry, Guiyang, Guizhou, China
- Key Laboratory for Biodiversity Conservation in the Karst Mountain Area of Southwestern China, National Forestry and Grassland Administration, Guiyang, Guizhou, China
| | - Juncai Wang
- Guizhou Academy of Sciences, Guiyang, Guizhou, China
| | - Fangjun Ding
- Guizhou Academy of Forestry, Guiyang, Guizhou, China
- Key Laboratory for Biodiversity Conservation in the Karst Mountain Area of Southwestern China, National Forestry and Grassland Administration, Guiyang, Guizhou, China
| | - Lianhui Wang
- Guizhou Academy of Forestry, Guiyang, Guizhou, China
- Key Laboratory for Biodiversity Conservation in the Karst Mountain Area of Southwestern China, National Forestry and Grassland Administration, Guiyang, Guizhou, China
| | - Yanbing Yang
- Guizhou Academy of Forestry, Guiyang, Guizhou, China
- Key Laboratory for Biodiversity Conservation in the Karst Mountain Area of Southwestern China, National Forestry and Grassland Administration, Guiyang, Guizhou, China
| | - Xinxiang Bai
- College of Forestry, Guizhou University, Guiyang, Guizhou, China
| | - Chengjiang Tan
- Guizhou Maolan National Nature Reserve Administration, Libo, Guizhou, China
| | - Xiaofeng Liao
- Guizhou Academy of Sciences, Guiyang, Guizhou, China
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Liu J, Zeng D, Huang Y, Zhong L, Liao J, Shi Y, Jiang H, Luo Y, Liang Y, Chai S. The structure and diversity of bacteria and fungi in the roots and rhizosphere soil of three different species of Geodorum. BMC Genomics 2024; 25:222. [PMID: 38418975 PMCID: PMC10903027 DOI: 10.1186/s12864-024-10143-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 02/19/2024] [Indexed: 03/02/2024] Open
Abstract
Shepherd's crook (Geodorum) is a genus of protected orchids that are valuable both medicinally and ornamentally. Geodorum eulophioides (GE) is an endangered and narrowly distributed species, and Geodorum densiflorum (GD) and Geodorum attenuatum (GA) are widespread species. The growth of orchids depend on microorganisms. However, there are few studies on the microbial structure in Geodorum, and little is known about the roles of microorganisms in the endangered mechanism of G. eulophioides. This study analyzed the structure and composition of bacterial and fungal communities in the roots and rhizosphere soil of GE, GD, and GA. The results showed that Delftia, Bordetella and norank_f_Xanthobacteraceae were the dominant bacteria in the roots of Geodorum, while norank_f_Xanthobacteraceae, Gaiella and norank_f_norank_o_Gaiellales were the dominant bacteria in the rhizosphere soil of Geodorum. In the roots, the proportion of Mycobacterium in GD_roadside was higher than that in GD_understory, on the contrary, the proportion of Fusarium, Delftia and Bordetella in GD_roadside was lower than that in GD_understory. Compared with the GD_understory, the roots of GD_roadside had lower microbial diversity. In the endangered species GE, Russula was the primary fungus in the roots and rhizosphere soil, with fungal diversity lower than in the more widespread species. Among the widespread species, the dominant fungal genera in the roots and rhizosphere soil were Neocosmospora, Fusarium and Coprinopsis. This study enhances our understanding of microbial composition and diversity, providing fundamental information for future research on microbial contributions to plant growth and ecosystem function in Geodorum.
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Affiliation(s)
- Jianxiu Liu
- Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection, Guangxi Key Laboratory of Landscape Resources Conservation and Sustainable Utilization in Lijiang River Basin, College of Life Science, Guangxi Normal University, Guilin, China
| | - Danjuan Zeng
- Guangxi Key Laboratory of Plant Functional Phytochemicals and Sustainable Utilization, Guangxi Institute of Botany, the Chinese Academy of Sciences, Guilin, China
| | - Yang Huang
- School of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, Guilin, China
| | - Lisha Zhong
- Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection, Guangxi Key Laboratory of Landscape Resources Conservation and Sustainable Utilization in Lijiang River Basin, College of Life Science, Guangxi Normal University, Guilin, China
| | - Jialin Liao
- Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection, Guangxi Key Laboratory of Landscape Resources Conservation and Sustainable Utilization in Lijiang River Basin, College of Life Science, Guangxi Normal University, Guilin, China
| | - Yuxing Shi
- Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection, Guangxi Key Laboratory of Landscape Resources Conservation and Sustainable Utilization in Lijiang River Basin, College of Life Science, Guangxi Normal University, Guilin, China
| | - Haidu Jiang
- Guangxi Key Laboratory of Plant Functional Phytochemicals and Sustainable Utilization, Guangxi Institute of Botany, the Chinese Academy of Sciences, Guilin, China
| | - Yajin Luo
- Yachang Orchid National Nature Reserve Management Center, Baise, China
| | - Yu Liang
- Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection, Guangxi Key Laboratory of Landscape Resources Conservation and Sustainable Utilization in Lijiang River Basin, College of Life Science, Guangxi Normal University, Guilin, China.
| | - Shengfeng Chai
- Guangxi Key Laboratory of Plant Functional Phytochemicals and Sustainable Utilization, Guangxi Institute of Botany, the Chinese Academy of Sciences, Guilin, China.
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Reiter N, Dimon R, Arifin A, Linde C. Culture age of Tulasnella affects symbiotic germination of the critically endangered Wyong sun orchid Thelymitra adorata (Orchidaceae). MYCORRHIZA 2023; 33:409-424. [PMID: 37947881 DOI: 10.1007/s00572-023-01131-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 10/23/2023] [Indexed: 11/12/2023]
Abstract
Orchids (Orchidaceae) are dependent on mycorrhizal fungi for germination and to a varying extent as adult plants. We isolated fungi from wild plants of the critically endangered terrestrial orchid Thelymitra adorata and identified them using a multi-region barcoding approach as two undescribed Tulasnella species, one in each of phylogenetic group II and III (OTU1) of the Tulasnellaceae. Using symbiotic propagation methods, we investigated the role of Tulasnella identity (species and isolate) and age post isolation, on the fungus's ability and efficacy in germinating T. adorata. The group II isolate did not support germination. Seed germination experiments were conducted using either (i) three different isolates of OTU1, (ii) 4- and 12-week-old fungal cultures (post isolation) of a single isolate of OTU1, and (iii) T. subasymmetrica which is widespread and known to associate with other species of Thelymitra. Culture age and fungal species significantly (P < 0.05) affected the time to germination and percentage of seed germination, with greater and faster germination with 4-week-old cultures. Tulasnella subasymmetrica was able to germinate T. adorata to leaf stage, although at slightly lower germination percentages than OTU1. The ability of T. adorata to germinate with T. subasymmetrica may allow for translocation sites to be considered outside of its native range. Our findings on the age of Tulasnella culture affecting germination may have applications for improving the symbiotic germination success of other orchids. Furthermore, storage of Tulasnella may need to take account of the culture age post-isolation, with storage at - 80 °C as soon as possible recommended, post isolation.
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Affiliation(s)
- Noushka Reiter
- Royal Botanic Gardens Victoria, Science Division, Corner of Ballarto Road and Botanic Drive, Cranbourne, VIC, 3977, Australia.
- Ecology and Evolution, Research School of Biology, ANU College of Science, RN Robertson Building, 46 Sullivans Creek Road, The Australian National University, Canberra, ACT 2600, Australia.
| | - Richard Dimon
- Royal Botanic Gardens Victoria, Science Division, Corner of Ballarto Road and Botanic Drive, Cranbourne, VIC, 3977, Australia
- Research Centre for Ecosystem Resilience, Botanic Gardens of Sydney, Mrs Macquaries Rd, Sydney, NSW 2000, Australia
- Queensland Alliance of Agriculture and Food Innovation, University of Queensland, 306 Cermody Rd, St Lucia, QLD, Australia
| | - Arild Arifin
- Ecology and Evolution, Research School of Biology, ANU College of Science, RN Robertson Building, 46 Sullivans Creek Road, The Australian National University, Canberra, ACT 2600, Australia
- Department of Plant Pathology, Washington State University Tree Fruit Research and Extension Center, Wenatchee, WA, 98801, USA
| | - Celeste Linde
- Ecology and Evolution, Research School of Biology, ANU College of Science, RN Robertson Building, 46 Sullivans Creek Road, The Australian National University, Canberra, ACT 2600, Australia
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Yang H, Li NQ, Gao JY. A novel method to produce massive seedlings via symbiotic seed germination in orchids. FRONTIERS IN PLANT SCIENCE 2023; 14:1114105. [PMID: 36968353 PMCID: PMC10034380 DOI: 10.3389/fpls.2023.1114105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 02/27/2023] [Indexed: 06/18/2023]
Abstract
Orchids produce large numbers of dust-like seeds that rely heavily on orchid mycorrhizal fungi (OMFs) for germination. Using OMFs to facilitate orchid proliferation is considered an effective method for orchid conservation but still presents challenges in practice. In this study, orchid seed-fungus complexes, in which orchid seeds and fungal mycelia were embedded together to form granules, were developed as platforms to facilitate seed germination and seedling production. Overall, seedlings were produced by seed-fungus complexes for five orchid species with large variations in the percentages of seedlings produced among species/treatments. For the different fungal treatments in Dendrobium officinale, Sebacinales LQ performed much better than the other fungal strains. At 90 days after sowing, 75.8±2.6% seedlings were produced in the LQ treatment, which was significantly higher than in the Tulasnella sp. JM (22.0±3.0%) and Tulasnella sp. TPYD-2 (5.3±1.0%) treatments, as well as in the LQ and TPYD-2 cocultured treatment (40.4±3.2%), while no seedlings were formed in the Tulasnella sp. SSCDO-5 or control treatments. For the other four orchid species, only one compatible fungus for each species was used, and the percentages of seedlings in epiphytic Dendrobium devonianum (67.2±2.9%) and D. nobile (38.9±2.8%) were much higher than those in terrestrial Paphiopedilum spicerianum (2.9±1.1%) and Arundina graminifolia (6.7±2.1%) at 90 days after sowing. Adding 1% polymer water-absorbent resin to the seed-fungus complexes of D. officinale seeds with fungal strain Sebacinales LQ significantly increased seedling formation, while other additional substances showed negative effects on seedling formation. For the storage of seed-fungus complexes, it is recommended to store the seed-fungus complexes in valve bags at room temperature for a short time and at a low temperature of 4°C for no more than 30 days. As a platform for symbiotic seed germination, the seed-fungus complex can facilitate seed germination, produce seedlings and support subsequent seedling growth, and its seedling productivity depends on seed germination characteristics, seed viability, and the efficiency of fungi. Seed-fungus complexes have great potential to be used as propagules in orchid conservation.
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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: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [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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Ceratobasidium orchid mycorrhizal fungi reveal intraspecific variation and interaction with different nutrient media in symbiotic germination of Prasophyllum (Orchidaceae). Symbiosis 2022. [DOI: 10.1007/s13199-022-00874-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
AbstractUnderstanding how nutrient requirements of orchid mycorrhizal fungi (OMF) affect symbiotic germination is essential for the ex situ conservation of threatened orchids and their mycorrhizal symbioses. Yet the influence of isolate-level variation in OMF nutrient preferences on orchid germination is unknown. We tested germination of Prasophyllum frenchii (Orchidaceae) on 15 different media of varying carbon and macronutrient compositions with three Ceratobasidium isolates of the same operational taxonomic unit (OTU) as determined with internal transcribed spacer locus sequencing. There was a significant interaction between media and fungal isolate on percentage germination, with each isolate recording its highest percentage germination on different nutrient media (Isolate 9.3: 5.2 ± 1.4% on MOM–S; Isolate 8.2: 5.4 ± 1.1% on MOM + S; Isolate 4.3: 2.2 ± 0.5% on 1.25 g/L wheat bran agar). Across all isolates, germination (percentage germination > 0) occurred more frequently on wheat bran agar media (39.7% of plates) than on oatmeal agar media (6.0% of plates). There was also an effect of media type on aerial hyphal growth behaviour of the OMF isolate. All isolates supported growth through to adult flowering plants. We demonstrated that symbiotic germination of Prasophyllum is affected by media composition. Further, percentage germination and aerial hyphal growth behaviour differed significantly among OMF isolates of the same OTU. This illustrates that a diversity of functionally significant fungal strains occurs within a single OTU, a previously unknown aspect of OMF research with important ecological and conservation implications.
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Herrera H, Sanhueza T, da Silva Valadares RB, Matus F, Pereira G, Atala C, Mora MDLL, Arriagada C. Diversity of Root-Associated Fungi of the Terrestrial Orchids Gavilea lutea and Chloraea collicensis in a Temperate Forest Soil of South-Central Chile. J Fungi (Basel) 2022; 8:jof8080794. [PMID: 36012784 PMCID: PMC9409917 DOI: 10.3390/jof8080794] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 07/18/2022] [Accepted: 07/23/2022] [Indexed: 11/16/2022] Open
Abstract
The diversity of orchid mycorrhizal fungi (OMF) and other beneficial root-associated fungi in temperate forests has scarcely been examined. This study aimed to analyze the diversity of mycorrhizal and rhizosphere-associated fungal communities in the terrestrial orchids Gavilea lutea and Chloraea collicensis growing in high-orchid-population-density areas in the piedmont of the Andes Cordillera with native forest (Nothofagus-Araucaria) and Coastal Cordillera with an exotic plantation (Pinus-Eucalyptus) in south-central Chile. We focused on rhizosphere-inhabiting and peloton-associated OMF in a native forest (Andes Cordillera) and a mixed forest (Coastal Cordillera). The native terrestrial orchids G. lutea and C. collicensis were localized, mycorrhizal root segments were taken to isolate peloton-associated OMF, and rhizosphere soil was taken to perform the metabarcoding approach. The results revealed that Basidiomycota and Ascomycota were the main rhizosphere-inhabiting fungal phyla, showing significant differences in the composition of fungal communities in both sites. Sebacina was the most-abundant OMF genera in the rhizosphere of G. lutea growing in the native forest soil. In contrast, Thanatephorus was the most abundant mycorrhizal taxa growing in the rhizosphere of orchids from the Coastal Cordillera. Besides, other OMF genera such as Inocybe, Tomentella, and Mycena were detected. The diversity of OMF in pelotons differed, being mainly related to Ceratobasidium sp. and Tulasnella sp. These results provide evidence of differences in OMF from pelotons and the rhizosphere soil in G. lutea growing in the Andes Cordillera and a selection of microbial communities in the rhizosphere of C. collicensis in the Coastal Cordillera. This raises questions about the efficiency of propagation strategies based only on mycorrhizal fungi obtained by culture-dependent methods, especially in orchids that depend on non-culturable taxa for seed germination and plantlet development.
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Affiliation(s)
- Héctor Herrera
- Laboratorio de Biorremediación, Departamento de Ciencias Forestales, Facultad de Ciencias Agropecuarias y Forestales, Universidad de La Frontera, Temuco 4780000, Chile;
- Correspondence: (H.H.); (C.A.)
| | - Tedy Sanhueza
- Laboratorio de Biorremediación, Departamento de Ciencias Forestales, Facultad de Ciencias Agropecuarias y Forestales, Universidad de La Frontera, Temuco 4780000, Chile;
- Programa de Magister en Manejo de Recursos Naturales, Universidad de La Frontera, Casilla 54-D, Francisco Salazar 01145, Temuco 4780000, Chile
| | | | - Francisco Matus
- Laboratory of Conservation and Dynamics of Volcanic Soils, Department of Chemical Sciences and Natural Resources, Universidad de La Frontera, Temuco 4780000, Chile;
- Network for Extreme Environmental Research (NEXER), Universidad de La Frontera, Temuco 4780000, Chile
| | - Guillermo Pereira
- Departamento de Ciencias y Tecnología Vegetal, Laboratorio Biotecnología de Hongos, Universidad de Concepción, Los Angeles 4440000, Chile;
| | - Cristian Atala
- Instituto de Biología, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Valparaiso 2340000, Chile;
| | - María de la Luz Mora
- Scientific and Technological Bioresource Nucleus, Universidad de La Frontera, Temuco 4780000, Chile;
| | - Cesar Arriagada
- Laboratorio de Biorremediación, Departamento de Ciencias Forestales, Facultad de Ciencias Agropecuarias y Forestales, Universidad de La Frontera, Temuco 4780000, Chile;
- Correspondence: (H.H.); (C.A.)
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Davis B, Lim WH, Lambers H, Dixon KW, Read DJ. Inorganic phosphorus nutrition in green-leaved terrestrial orchid seedlings. ANNALS OF BOTANY 2022; 129:669-678. [PMID: 35247265 PMCID: PMC9113155 DOI: 10.1093/aob/mcac030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 03/04/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND AND AIMS Many terrestrial orchids have an obligate dependence on their mycorrhizal associations for nutrient acquisition, particularly during germination and early seedling growth. Though important in plant growth and development, phosphorus (P) nutrition studies in mixotrophic orchids have been limited to only a few orchid species and their fungal symbionts. For the first time, we demonstrate the role of a range of fungi in the acquisition and transport of inorganic P to four phylogenetically distinct green-leaved terrestrial orchid species (Diuris magnifica, Disa bracteata, Pterostylis sanguinea and Microtis media subsp. media) that naturally grow in P-impoverished soils. METHODS Mycorrhizal P uptake and transfer to orchids was determined and visualized using agar microcosms with a diffusion barrier between P source (33P orthophosphate) and orchid seedlings, allowing extramatrical hyphae to reach the source. KEY RESULTS Extramatrical hyphae of the studied orchid species were effective in capturing and transporting inorganic P into the plant. Following 7 d of exposure, between 0.5 % (D. bracteata) and 47 % (D. magnifica) of the P supplied was transported to the plants (at rates between 0.001 and 0.097 fmol h-1). This experimental approach was capable of distinguishing species based on their P-foraging efficiency, and highlighted the role that fungi play in P nutrition during early seedling development. CONCLUSIONS Our study shows that orchids occurring naturally on P-impoverished soils can obtain significant amounts of inorganic P from their mycorrhizal partners, and significantly more uptake of P supplied than previously shown in other green-leaved orchids. These results provide support for differences in mycorrhiza-mediated P acquisition between orchid species and fungal symbionts in green-leaved orchids at the seedling stage. The plant-fungus combinations of this study also provide evidence for plant-mediated niche differentiation occurring, with ecological implications in P-limited systems.
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Affiliation(s)
- Belinda Davis
- Kings Park Science, Biodiversity and Conservation Science, Department of Biodiversity, Conservation and Attractions, 2 Kattidj Close, Kings Park, WA, Australia
- School of Biological Sciences, The University of Western Australia, Crawley, Perth, WA, Australia
| | - Wei-Han Lim
- Kings Park Science, Biodiversity and Conservation Science, Department of Biodiversity, Conservation and Attractions, 2 Kattidj Close, Kings Park, WA, Australia
- School of Biological Sciences, The University of Western Australia, Crawley, Perth, WA, Australia
| | - Hans Lambers
- School of Biological Sciences, The University of Western Australia, Crawley, Perth, WA, Australia
- Environment and Agriculture, Curtin University, Bentley, 6102, Western Australia
| | - Kingsley W Dixon
- School of Biological Sciences, The University of Western Australia, Crawley, Perth, WA, Australia
- Environment and Agriculture, Curtin University, Bentley, 6102, Western Australia
| | - David J Read
- School of Biological Sciences, The University of Western Australia, Crawley, Perth, WA, Australia
- Department of Animal and Plant Sciences, University of Sheffield, Alfred Denny Building, Western Bank, Sheffield, UK
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