Interspecific Mycorrhizal Networks and Non-networking Hosts: Exploring the Ecology of the Host Genus Alnus

Kennedy, Peter G.; Walker, Jennifer K. M.; Bogar, Laura M.

doi:10.1007/978-94-017-7395-9_8

Cited by 28 publications

(27 citation statements)

References 88 publications

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“…In spite of multiple examples of high unilateral or reciprocal specialization in EcM fungal symbiosis, such as Alnus and Alnusassociated fungi, Suillineae, Leccinum and Gnetum (Bruns et al, 2002;Kennedy et al, 2015), the average host effect on fungal community composition was comparable with that of root and leaf endophytes, as well as AM and ErM fungi, for which such examples of specificity are not known. We found that narrowly confined host associations were uncommon among EcM fungi, lowering the overall host effect among this group.…”

Section: Researchmentioning

confidence: 91%

Host preference and network properties in biotrophic plant–fungal associations

et al. 2017

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Analytical methods can offer insights into the structure of biological networks, but mechanisms that determine the structure of these networks remain unclear. We conducted a synthesis based on 111 previously published datasets to assess a range of ecological and evolutionary mechanisms that may influence the plant-associated fungal interaction networks. We calculated the relative host effect on fungal community composition and compared nestedness and modularity among different mycorrhizal types and endophytic fungal guilds. We also assessed how plant-fungal network structure was related to host phylogeny, environmental and sampling properties. Orchid mycorrhizal fungal communities responded most strongly to host identity, but the effect of host was similar among all other fungal guilds. Community nestedness, which did not differ among fungal guilds, declined significantly with increasing mean annual precipitation on a global scale. Orchid and ericoid mycorrhizal fungal communities were more modular than ectomycorrhizal and root endophytic communities, with arbuscular mycorrhizal fungi in an intermediate position. Network properties among a broad suite of plant-associated fungi were largely comparable and generally unrelated to phylogenetic distance among hosts. Instead, network metrics were predominantly affected by sampling and matrix properties, indicating the importance of study design in properly inferring ecological patterns.

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Section: Researchmentioning

confidence: 91%

Host preference and network properties in biotrophic plant–fungal associations

et al. 2017

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“…Alders (Alnus spp., Betulaceae family) are involved in tripartite symbioses with ectomycorrhizal (ECM) fungi and nitrogen-fixing actinobacteria belonging to the Frankia genus. According to their subgenus or species, alders are associated with specific Frankia subgroups (4-6) and a few specific ECM fungi (7)(8)(9)(10). This specificity has been confirmed on a worldwide scale, as the biogeography of ECM fungi and Frankia is mainly explained by their host biogeography and by abiotic factors, such as elevation or organic matter content (11)(12)(13).…”

mentioning

confidence: 84%

“…Compatible interactions between Alnus species and their specific Frankia strains may also affect their interaction with ECM fungi. Indeed, root nodule formation often precedes specific ECM association, and several studies have demonstrated that nodulation efficiency affects ECM diversity (10,19,20). As a consequence, and given that Spϩ and SpϪ Frankia strains differ in their infectivities (15), nitrogen fixation activities (16), and secondary metabolite profiles (21), in planta sporulation of Frankia spp.…”

mentioning

confidence: 99%

In Planta Sporulation of Frankia spp. as a Determinant of Alder-Symbiont Interactions

Schwob

Roy

Pozzi

et al. 2018

Appl Environ Microbiol

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The genus forms symbiosis with the actinobacteria spp. and ectomycorrhizal fungi. Two types of lineages can be distinguished based on their ability to sporulate Spore-positive (Sp+) strains are predominant on and in highlands, while spore-negative (Sp-) strains are mainly associated with in lowlands. Here, we investigated whether the Sp+ predominance in nodules is due to host selection of certain genotypes from soil communities or the result of the ecological history of the alder stand soil, as well as the effect of the sporulation genotype on the ectomycorrhizal (ECM) communities. Trapping experiments were conducted using ,, and plantlets on 6 soils, differing in the alder species and the frequency of Sp+ nodules in the field. Higher diversity of spp. and variation in Sp+ frequencies were observed in the trapping than in the fields. Both indigenous and trapping species shape community structure in trapped nodules. Nodulation impediments were observed under several trapping conditions in Sp+ soils, supporting a narrower host range of Sp+ species. and were able to associate equally with compatible Sp+ and Sp- strains in the greenhouse. Additionally, no host shift was observed for -specific ECM, and the sporulation genotype of spp. defined the ECM communities on the host roots. The symbiotic association is likely determined by the host range, the soil history, and the type of species. These results provide an insight into the biogeographical drivers of alder symbionts in the Holarctic region. Most -actinorhiza plant symbioses are capable of high rates of nitrogen fixation comparable to those found on legumes. Yet, our understanding of the ecology and distribution of spp. is still very limited. Several studies have focused on the distribution patterns of spp., demonstrating a combination of host and pedoclimatic parameters in their biogeography. However, very few have considered the sporulation form of the strain, although it is a unique feature among all symbiotic plant-associated microbes. Compared with Sp- strains, Sp+ strains would be obligate symbionts that are highly dependent on the presence of a compatible host species and with lower efficiency in nitrogen fixation. Understanding the biogeographical drivers of Sp+ strains might help elucidate the ecological role of sporulation and the extent to which this trait mediates host-partner interactions in the alder--ECM fungal symbiosis.

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“…In the case of Alnus , specificity is linked to the co‐migration of plants and their ECM fungi from the northern hemisphere (Kennedy et al ., ). A three‐way interaction among Alnus , ECM fungi and Frankia bacteria likely promotes habitat filtering which excludes nonspecialist ECM fungi (Kennedy et al ., ).…”

Section: Beta Diversity Patterns In Tropical Ecm Fungal Communitiesmentioning

confidence: 97%

Ectomycorrhizal associations in the tropics – biogeography, diversity patterns and ecosystem roles

2018

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Contents Summary 1076 I. Introduction 1076 II. Historical overview 1077 III. Identities and distributions of tropical ectomycorrhizal plants 1077 IV. Dominance of tropical forests by ECM trees 1078 V. Biogeography of tropical ECM fungi 1081 VI. Beta diversity patterns in tropical ECM fungal communities 1082 VII. Conclusions and future research 1086 Acknowledgements 1087 References 1087 SUMMARY: Ectomycorrhizal (ECM) associations were historically considered rare or absent from tropical ecosystems. Although most tropical forests are dominated by arbuscular mycorrhizal (AM) trees, ECM associations are widespread and found in all tropical regions. Here, we highlight emerging patterns of ECM biogeography, diversity and ecosystem functions, identify knowledge gaps, and offer direction for future research. At the continental and regional scales, tropical ECM systems are highly diverse and vary widely in ECM plant and fungal abundance, diversity, composition and phylogenetic affinities. We found strong regional differences among the dominant host plant families, suggesting that biogeographical factors strongly influence tropical ECM symbioses. Both ECM plants and fungi also exhibit strong turnover along altitudinal and soil fertility gradients, suggesting niche differentiation among taxa. Ectomycorrhizal fungi are often more abundant and diverse in sites with nutrient-poor soils, suggesting that ECM associations can optimize plant nutrition and may contribute to the maintenance of tropical monodominant forests. More research is needed to elucidate the diversity patterns of ECM fungi and plants in the tropics and to clarify the role of this symbiosis in nutrient and carbon cycling.

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Interspecific Mycorrhizal Networks and Non-networking Hosts: Exploring the Ecology of the Host Genus Alnus

Cited by 28 publications

References 88 publications

Host preference and network properties in biotrophic plant–fungal associations

Host preference and network properties in biotrophic plant–fungal associations

In Planta Sporulation of Frankia spp. as a Determinant of Alder-Symbiont Interactions

Ectomycorrhizal associations in the tropics – biogeography, diversity patterns and ecosystem roles

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