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Karst J, Jones MD, Hoeksema JD. Positive citation bias and overinterpreted results lead to misinformation on common mycorrhizal networks in forests. Nat Ecol Evol 2023; 7:501-511. [PMID: 36782032 DOI: 10.1038/s41559-023-01986-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 01/06/2023] [Indexed: 02/15/2023]
Abstract
A common mycorrhizal network (CMN) is formed when mycorrhizal fungal hyphae connect the roots of multiple plants of the same or different species belowground. Recently, CMNs have captured the interest of broad audiences, especially with respect to forest function and management. We are concerned, however, that recent claims in the popular media about CMNs in forests are disconnected from evidence, and that bias towards citing positive effects of CMNs has developed in the scientific literature. We first evaluated the evidence supporting three common claims. The claims that CMNs are widespread in forests and that resources are transferred through CMNs to increase seedling performance are insufficiently supported because results from field studies vary too widely, have alternative explanations or are too limited to support generalizations. The claim that mature trees preferentially send resources and defence signals to offspring through CMNs has no peer-reviewed, published evidence. We next examined how the results from CMN research are cited and found that unsupported claims have doubled in the past 25 years; a bias towards citing positive effects may obscure our understanding of the structure and function of CMNs in forests. We conclude that knowledge on CMNs is presently too sparse and unsettled to inform forest management.
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Affiliation(s)
- Justine Karst
- Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada.
| | - Melanie D Jones
- Department of Biology, University of British Columbia, Kelowna, British Columbia, Canada
| | - Jason D Hoeksema
- Department of Biology, University of Mississippi, Oxford, MS, USA
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Suetsugu K, Matsuoka S, Shutoh K, Okada H, Taketomi S, Onimaru K, Tanabe AS, Yamanaka H. Mycorrhizal communities of two closely related species, Pyrola subaphylla and P. japonica, with contrasting degrees of mycoheterotrophy in a sympatric habitat. MYCORRHIZA 2021; 31:219-229. [PMID: 33215330 DOI: 10.1007/s00572-020-01002-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 10/29/2020] [Indexed: 06/11/2023]
Abstract
Mycoheterotrophic plants typically form associations with a narrow range of mycorrhizal fungi. Consequently, mycorrhizal specialization is often considered to be an important step in mycoheterotrophic evolution. However, it remains unclear whether such specialization is likely to occur in plants of the genus Pyrola, which are generally associated with fungi in multiple ectomycorrhizal families. Here, we investigated the mycorrhizal communities of a nearly fully mycoheterotrophic Pyrola species (Pyrola subaphylla), a closely related partially mycoheterotrophic Pyrola species (Pyrola japonica), and a co-occurring autotrophic ectomycorrhizal tree, Quercus crispula, which is their potential carbon source, in a cool-temperate Japanese forest. High-throughput DNA sequencing revealed that numerous common ectomycorrhizal OTUs interact with the two Pyrola species and Q. crispula, thereby providing an opportunity to exploit a certain amount of carbon from common mycorrhizal networks. In addition, not only P. japonica but also P. subaphylla exhibited exceptionally high alpha mycobiont diversity, with 52 ectomycorrhizal OTUs belonging to 12 families being identified as P. subaphylla mycobionts and 69 ectomycorrhizal OTUs in 18 families being detected as P. japonica mycobionts. Nonetheless, the beta mycobiont diversity of P. subaphylla and P. japonica individuals was significantly lower than that of Q. crispula. Moreover, the beta mycobiont diversity of P. subaphylla was found to be significantly lower than that of P. japonica. Therefore, despite their seemingly broad mycorrhizal interactions, the two Pyrola species (particularly P. subaphylla) showed consistent fungal associations, suggesting that mycorrhizal specialization may have developed during the course of mycoheterotrophic evolution within the genus Pyrola.
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Affiliation(s)
- Kenji Suetsugu
- Department of Biology, Graduate School of Science, Kobe University, Kobe, Hyogo, 657-8501, Japan.
| | - Shunsuke Matsuoka
- Graduate School of Simulation Studies, University of Hyogo, Kobe, Hyogo, 650-0047, Japan
| | - Kohtaroh Shutoh
- The Hokkaido University Museum, Hokkaido University, Sapporo, Hokkaido, 060-0810, Japan
| | - Hidehito Okada
- Department of Biology, Graduate School of Science, Kobe University, Kobe, Hyogo, 657-8501, Japan
| | - Shintaro Taketomi
- Department of Biology, Graduate School of Science, Kobe University, Kobe, Hyogo, 657-8501, Japan
| | - Kaede Onimaru
- Department of Biology, Graduate School of Science, Kobe University, Kobe, Hyogo, 657-8501, Japan
| | - Akifumi S Tanabe
- Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi, 980-8578, Japan
| | - Hiroki Yamanaka
- Faculty of Science and Technology, Ryukoku University, Otsu, Shiga, 520-2194, Japan
- Center for Biodiversity Science, Ryukoku University, Otsu, Shiga, 520-2194, Japan
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Herrera H, Soto J, de Bashan LE, Sampedro I, Arriagada C. Root-Associated Fungal Communities in Two Populations of the Fully Mycoheterotrophic Plant Arachnitis uniflora Phil. (Corsiaceae) in Southern Chile. Microorganisms 2019; 7:E586. [PMID: 31756978 PMCID: PMC6955791 DOI: 10.3390/microorganisms7120586] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 11/03/2019] [Accepted: 11/19/2019] [Indexed: 02/07/2023] Open
Abstract
The microbiological interactions of the roots of non-photosynthetic plants in South America have been scarcely explored. This study analyzes culturable fungal diversity associated with the mycoheterotrophic plant Arachnitis uniflora Phil. (Corsiaceae) in southern Chile, growing in two different understoreys of native (Nothofagus-dominated) and mixed forest (native, Cupressus sempervirens, and Pinus radiata). Rhizospheric and endophytic fungi were isolated, cultured, and purified to identify microorganisms associated with A. uniflora roots. We showed the different fungi associated with the plant, and that these distributions are influenced by the sampling site. We isolated 410 fungal strains (144 endophytic and 266 from the rhizosphere). We identified 13 operative taxonomical units from plants sampled in the mixed forest, while 15 were from the native forest. Rhizospheric microorganisms were mainly related to Penicillium spp., whereas some pathogenic and saprophytic strains were more frequent inside the roots. Our results have also shown that the fungal strains are weak for phosphate solubilization, but other pathways such as organic acid exudation and indole acetic acid production can be considered as major mechanisms to stimulate plant growth. Our results point to new fungal associates of A. uniflora plants reported in Andean ecosystems, identifying new beneficial endophytic fungi associated with roots of this fully mycoheterotrophic plant.
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Affiliation(s)
- Hector Herrera
- Laboratorio de Biorremediación, Departamento de Ciencias Forestales, Facultad de Ciencias Agropecuarias y Forestales, Universidad de La Frontera, 01145 Temuco, Chile; (H.H.); (J.S.)
| | - Javiera Soto
- Laboratorio de Biorremediación, Departamento de Ciencias Forestales, Facultad de Ciencias Agropecuarias y Forestales, Universidad de La Frontera, 01145 Temuco, Chile; (H.H.); (J.S.)
| | - Luz E. de Bashan
- The Bashan Institute of Science, 1730 Post Oak Court, Auburn, AL 36830, USA;
- Department of Entomology and Plant Pathology, 301 Funchess Hall, Auburn University, Auburn, AL 36849, USA
- Environmental Microbiology Group, Northwestern Center for Biological Research (CIBNOR), Calle IPN 195, 23096 La Paz, B.C.S., Mexico
| | - Inmaculada Sampedro
- Departamento de Microbiología, Facultad de Farmacia, Universidad de Granada, 18071 Granada, Spain;
| | - Cesar Arriagada
- Laboratorio de Biorremediación, Departamento de Ciencias Forestales, Facultad de Ciencias Agropecuarias y Forestales, Universidad de La Frontera, 01145 Temuco, Chile; (H.H.); (J.S.)
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