Variation in nutrient-acquisition patterns by mycorrhizal fungi of rare and common orchids explains diversification in a global biodiversity hotspot

Nurfadilah, Siti; Swarts, N; Dixon, Kingsley W.; Lambers, Hans; Merritt, David J.

doi:10.1093/aob/mct064

Cited by 67 publications

(78 citation statements)

References 57 publications

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“…Nurfadilah et al . () reported different N source preference in orchid mycorrhizal fungi because isolates in the genus Tulasnella could use ammonium but not nitrate as inorganic N forms, whereas isolates in the genus Ceratobasidium could use both ammonium and nitrate. Growth of T. calospora isolate AL13/4D on different N sources confirmed a preference for ammonium and organic N sources, like other cultivable orchid mycorrhizal fungi (Hadley & Ong, ; Nurfadilah et al ., ).…”

Section: Discussionmentioning

confidence: 99%

Fungal and plant gene expression in the Tulasnella calospora–Serapias vomeracea symbiosis provides clues about nitrogen pathways in orchid mycorrhizas

et al. 2016

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Summary Orchids are highly dependent on their mycorrhizal fungal partners for nutrient supply, especially during early developmental stages. In addition to organic carbon, nitrogen (N) is probably a major nutrient transferred to the plant because orchid tissues are highly N‐enriched. We know almost nothing about the N form preferentially transferred to the plant or about the key molecular determinants required for N uptake and transfer. We identified, in the genome of the orchid mycorrhizal fungus Tulasnella calospora, two functional ammonium transporters and several amino acid transporters but found no evidence of a nitrate assimilation system, in agreement with the N preference of the free‐living mycelium grown on different N sources. Differential expression in symbiosis of a repertoire of fungal and plant genes involved in the transport and metabolism of N compounds suggested that organic N may be the main form transferred to the orchid host and that ammonium is taken up by the intracellular fungus from the apoplatic symbiotic interface. This is the first study addressing the genetic determinants of N uptake and transport in orchid mycorrhizas, and provides a model for nutrient exchanges at the symbiotic interface, which may guide future experiments.

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Section: Discussionmentioning

confidence: 99%

Fungal and plant gene expression in the Tulasnella calospora–Serapias vomeracea symbiosis provides clues about nitrogen pathways in orchid mycorrhizas

et al. 2016

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“…This reinforces the nutrient access studies by Nurfadilah et al . () and clearly raises the prediction that some orchid–OMF combinations will be more beneficial than others and that it will be habitat dependent.…”

Section: Orchid Mycorrhizal Fungus Identity and Orchid Distribution Amentioning

confidence: 94%

“…Fungi associated with orchids have diverse nutritional needs (Nurfadilah et al ., ), but it is not currently thought that they need to associate with or are necessarily co‐distributed with orchids. A few studies have demonstrated or intimated that orchids may contribute carbon to their fungi (Cameron et al ., , ; Hynson et al ., ; Ogura‐Tsujita et al ., ; Liebel et al ., ), suggesting that association with the orchid might benefit the fungus.…”

Section: Orchid Mycorrhizaementioning

confidence: 99%

“…Arbuscular and ectomycorrhizal fungi and genotypes have been shown to differ in their ability to support their plant hosts (e.g. Johnson et al ., ; Roger et al ., ; Hazard et al ., ,b; Shi et al ., ), and OMFs have been shown to differ in their ability to access distinct nitrogen sources (Nurfadilah et al ., ) and to support orchids in vitro (e.g. Warcup, ; Masuhara & Katsuya, ; Rasmussen & Whigham, ; McCormick et al ., ).…”

Section: Orchid Mycorrhizal Fungus Identity and Orchid Distribution Amentioning

confidence: 99%

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Mycorrhizal fungi affect orchid distribution and population dynamics

2018

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Symbioses are ubiquitous in nature and influence individual plants and populations. Orchids have life history stages that depend fully or partially on fungi for carbon and other essential resources. As a result, orchid populations depend on the distribution of orchid mycorrhizal fungi (OMFs). We focused on evidence that local-scale distribution and population dynamics of orchids can be limited by the patchy distribution and abundance of OMFs, after an update of an earlier review confirmed that orchids are rarely limited by OMF distribution at geographic scales. Recent evidence points to a relationship between OMF abundance and orchid density and dormancy, which results in apparent density differences. Orchids were more abundant, less likely to enter dormancy, and more likely to re-emerge when OMF were abundant. We highlight the need for additional studies on OMF quantity, more emphasis on tropical species, and development and application of next-generation sequencing techniques to quantify OMF abundance in substrates and determine their function in association with orchids. Research is also needed to distinguish between OMFs and endophytic fungi and to determine the function of nonmycorrhizal endophytes in orchid roots. These studies will be especially important if we are to link orchids and OMFs in efforts to inform conservation.

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“…The first step in this direction has been taken by Nurfadilah et al . (), who examined the nutrient acquisition abilities of fungi associated with several species of Australian orchids. They found that fungi that associated with rare, habitat‐specialist orchids were able to utilize a narrower range of nutrient sources than those that associated with more widespread orchids, suggesting a possible mechanism for the connection between mycorrhizal fungus distribution and abundance and orchid rarity.…”

Section: Local‐scale Dynamicsmentioning

confidence: 99%

What constrains the distribution of orchid populations?

2013

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Summary The distribution and abundance of orchid populations depend on a suite of biological and ecological factors, including seed production and dispersal, availability of mycorrhizal fungi and appropriate environmental conditions, with the weighting of these factors depending on the spatial scale considered. Disentangling the factors determining successful orchid establishment represents a major challenge, involving seed germination experiments, molecular techniques and assessment of environmental conditions. Identification of fungi from large‐scale surveys of mycorrhizal associations in a range of orchid species has shown that mycorrhizal fungi may be widespread and occur in varied habitats. Further, a meta‐analysis of seed introduction experiments revealed similar seed germination in occupied and unoccupied habitat patches. Orchid rarity was also unrelated to mycorrhizal specificity. Nonetheless, seed germination within sites appears to depend on both biotic and abiotic conditions. In the few cases that have been examined, coexisting orchids have distinct mycorrhizal communities and show strong spatial segregation, suggesting that mycorrhizal fungi are important drivers of niche partitioning and contribute to orchid coexistence. A broader investigation of orchid mycorrhizal fungus distribution in the soil, coupled with fungus and recruitment mapping, is needed to translate fungal abundance to orchid population dynamics and may lead to better orchid conservation.

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Variation in nutrient-acquisition patterns by mycorrhizal fungi of rare and common orchids explains diversification in a global biodiversity hotspot

Cited by 67 publications

References 57 publications

Fungal and plant gene expression in the Tulasnella calospora–Serapias vomeracea symbiosis provides clues about nitrogen pathways in orchid mycorrhizas

Fungal and plant gene expression in the Tulasnella calospora–Serapias vomeracea symbiosis provides clues about nitrogen pathways in orchid mycorrhizas

Mycorrhizal fungi affect orchid distribution and population dynamics

What constrains the distribution of orchid populations?

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