Article

Ectomycorrhizal host specificity in a changing world: Can legacy effects explain anomalous current associations?

Wiley
New Phytologist
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Abstract

Despite the importance of ectomycorrhizal ( ECM ) fungi in forest ecosystems, knowledge about the ecological and co‐evolutionary mechanisms underlying ECM host associations remains limited. Using a widely distributed group of ECM fungi known to form tight associations with trees in the family Pinaceae, we characterized host specificity among three unique Suillus –host species pairs using a combination of field root tip sampling and experimental bioassays. We demonstrate that the ECM fungus S. subaureus can successfully colonize Quercus hosts in both field and glasshouse settings, making this species unique in an otherwise Pinaceae‐specific clade. Importantly, however, we found that the colonization of Quercus by S. subaureus required co‐planting with a Pinaceae host. While our experimental results indicate that gymnosperms are required for the establishment of new S. subaureus colonies, Pineaceae hosts are locally absent at both our field sites. Given the historical presence of Pineaceae hosts before human alteration, it appears the current S. subaureus–Quercus associations represent carryover from past host presence. Collectively, our results suggest that patterns of ECM specificity should be viewed not only in light of current forest community composition, but also as a legacy effect of host community change over time.

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... We expected that (H1) Douglas-fir and oak would each recruit a distinct fungal community, with levels of taxonomic (amplicon sequence variant; ASV) richness and root colonization highest when inoculated with home soil. Yet, as even host-specific ectomycorrhizal fungi may colonize secondary hosts via hyphal spread from a primary host (Lofgren et al., 2018), we also expected that (H2) growing a seedling with a heterospecific (that is, an oak if the focal seedling were a Douglas-fir, or a Douglas-fir if the focal seedling were an oak) would expand its root-associated fungal community and increase root colonization. We expect that this fungal facilitation effect should be particularly strong in soil not sourced from a seedling's own ecosystem type, as a larger proportion of fungi in these samples are likely to prefer the other tree species as a primary host. ...
... We then tested whether the proportion of reads belonging to unique ASVs differed between seedling species when they were grown separately with the same inoculum treatment. Finally, as prior research finds host-specificity in Pinaceae-associated ectomycorrhizal fungi, we examined whether the proportion of reads belonging to unique ASVs was greater in Douglas-fir seedlings than in oaks when they were grown together, which enables hyphal spread from a primary to a secondary host (Lofgren et al., 2018). For these two tests, we first used linear regression to examine whether the difference in number of growth days between the oak and Douglas-fir seedlings in question predicted variation in the proportion of unique reads found in either one. ...
... Instead, for Douglas-firs establishing in oak woodlands, fire appears to remove the fungal colonization barrier that otherwise would need to be alleviated through oak facilitation, perhaps by activating dormant spores from fire-adapted Rhizopogon species (Figure 5;Peay et al., 2009). In contrast, the effect of Douglas-fir on oak root system fungal richness was most strongly positive with soils specifically from fire-affected Douglas-fir forests (Table S5), where Douglas-fir seedlings facilitated secondary Rhizopogon affiliation with oaks ( Figure 5; Lofgren et al., 2018). In other words, we find that in post-fire landscapes, facilitation by oaks is no longer necessary for Douglas-firs to become fungally colonized in oak woodlands, and the ability of Douglas-fir to diversify oak rootassociated fungal communities in Douglas-fir forests is increased. ...
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Self‐reinforcing differences in fire frequency help closed‐canopy forests, which resist fire, and open woodlands, which naturally burn often, to co‐occur stably at landscape scales. Forest tree seedlings, which could otherwise encroach and overgrow woodlands, are killed by regular fire, yet fire has other effects that may also influence these feedbacks. In particular, many forest trees require symbiotic ectomycorrhizal fungi in order to establish. By restructuring soil fungal communities, fire might affect the availability of symbionts or the potential for symbiont sharing between encroaching trees and woodland vegetation. To investigate this possibility, we performed a soil bioassay experiment using inoculum from burned and unburned oak woodlands and Douglas‐fir forests. We examined how fire, ecosystem type, and neighboring heterospecific seedlings affect fungal root community assembly of Douglas‐firs and oaks. We asked whether heterospecific seedlings facilitated fungal colonization of seedling roots in non‐native soil, and if so, whether fire influenced this interaction. External fungal colonization of oak roots was more influenced by fire and ecosystem type than by the presence of a Douglas‐fir, and oaks increased the likelihood that Douglas‐fir roots would be colonized by fungi in oak woodland soil. Yet, fire increased colonization of Douglas‐fir in oak soil, diminishing the otherwise crucial role played by oak facilitation. Fire also strengthened the positive effect of Douglas‐firs on oak root‐associated fungal diversity in Douglas‐fir forest soil. Prior work shows that fire supports woodland ecosystems by stemming recruitment of encroaching seedlings. Here, we find evidence that it may contrastingly reduce fungal limitation of invasive seedling growth and establishment, otherwise relieved only by facilitation. Future work can investigate how these opposing effects might contribute to the net impact of changes in fire regime on landcover stability. Read the free Plain Language Summary for this article on the Journal blog.
... The sister abietoid clade, which contains ECM host genera such as Abies and Tsuga, has not been documented to host Suillus fungi. Although these genuslevel patterns of Suillus host specificity are well recognized from an evolutionary perspective (Nguyen et al. 2016), the specificity of ECM fungi has been shown to be ecologically context dependent Bogar and Kennedy 2013;Moeller et al. 2015;Lofgren et al. 2018). Specifically, the neighborhood in which plants are present may shift patterns of host specificity through colonization of alternative hosts via mycelial spread. ...
... This phenomenon was well documented by Massicotte et al. (1994), who found that Rhizopogon species were able to associate with hosts including Abies grandis, Tsuga heterophylla, Pseudotsuga menziesii, and Picea sitchensis, but only when they were co-planted with Pinus ponderosa seedlings. More recently, a similar pattern was documented with Suillus subaureus, where Lofgren et al. (2018) found that ECM colonization of S. subaureus on Quercus seedlings required co-planting with a Pinaceae host (Pinus strobus). In both cases, the presence of a "primary" host was shown to be required for the germination of Rhizopogon or Suillus spores ahead of mycelial colonization on "secondary" hosts. ...
... In cases where ECM fungal colonization does occur on secondary hosts, the extent to which these associations can be considered ecologically stable in the long term is unclear, although our work here and elsewhere (Lofgren et al. 2018) showed that at last three members of the genus Suillus (S. subaureus, S. punctatipes, and S. glandulosus) can associate with alternative hosts. It is possible that the colonization of secondary hosts be greatly facilitated by carbohydrate flow from the primary host into the fungal mycelium (Finlay 1989), and if the primary host is eliminated, secondary host colonization might significantly decline. ...
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Suillus is among the best-known examples of an ectomycorrhizal (ECM) fungal genus that demonstrates a high degree of host specificity. Currently recognized host genera of Suillus include Larix, Pinus, and Pseudotsuga, which all belong to the pinoid clade of the family Pinaceae. Intriguingly, Suillus sporocarps have been sporadically collected in forests in which known hosts from these genera are locally absent. To determine the capacity of Suillus to associate with alternative hosts in both the pinoid and abietoid clades of Pinaceae, we examined the host associations of two Suillus species (S. punctatipes and S. glandulosus) through field-based root tip sampling and seedling bioassays. Root tip collections underneath Suillus sporocarps were molecularly identified (fungi: nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 [ITS barcode]; plant: trnL) to assess the association with multiple hosts. The bioassays contained both single- and two-species treatments, including a primary (Larix or Pseudotsuga) and a secondary (Picea, Pinus, or Abies) host. For the S. punctatipes bioassay, an additional treatment in which the primary host was removed after 8 mo was included to assess the effect of primary host presence on longer-term ECM colonization. The field-based results confirmed that Suillus fungi were able to associate with Abies and Tsuga hosts, representing novel host genera for this genus. In the bioassays, colonization on the primary hosts was detected in both single- and two-species treatments, but no colonization was present when Picea and Abies hosts were grown alone. Removal of a primary host had no effect on percent ECM colonization, suggesting that primary hosts are not necessary for sustaining Suillus colonization once they are successfully established on secondary hosts. Collectively, our results indicate that host specificity is more flexible in this genus than previously acknowledged and help to explain the presence of Suillus in forests where recognized hosts are not present.
... We recently became interested in the aforementioned tradeoffs to help understand the enigmatic life history strategy of the ECM fungus, Suillus subaureus. Unlike other Suillus species, which are largely host-specific to one of three different host genera in the family Pinaceae [31], S. subaureus is able to colonize both Pinus and Quercus host species [32]. However, this expansion of host range is complicated by the fact that the spores of S. subaureus will only germinate in the presence of Pinaceae host [32]. ...
... Unlike other Suillus species, which are largely host-specific to one of three different host genera in the family Pinaceae [31], S. subaureus is able to colonize both Pinus and Quercus host species [32]. However, this expansion of host range is complicated by the fact that the spores of S. subaureus will only germinate in the presence of Pinaceae host [32]. As such, the establishment on Quercus individuals requires spread of S. subaureus mycelium growing from colonized Pinaceae root tips. ...
... Under those nearby Pinus individuals, we have encountered other Suillus species but never encountered S. subaureus despite extensive searching. Thus, it appears that the presence of S. subaureus on Quercus hosts represents a legacy effect of Pinus individuals that are no longer present [32]. Further, in our extensive collecting of Suillus throughout Minnesota, USA, we have regularly encountered many other Suillus species in Pinus forests, but only S. subaureus in two locations. ...
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Two common ecological assumptions are that host generalist and rare species are poorer competitors relative to host specialist and more abundant counterparts. While these assumptions have received considerable study in both plant and animals, how they apply to ectomycorrhizal fungi remains largely unknown. To investigate how interspecific competition may influence the anomalous host associations of the rare ectomycorrhizal generalist fungus, Suillus subaureus, we conducted a seedling bioassay. Pinus strobus seedlings were inoculated in single- or two-species treatments of three Suillus species: S. subaureus, S. americanus, and S. spraguei. After 4 and 8 months of growth, seedlings were harvested and scored for mycorrhizal colonization as well as dry biomass. At both time points, we found a clear competitive hierarchy among the three ectomycorrhizal fungal species: S. americanus > S. subaureus > S. spraguei, with the competitive inferior, S. spraguei, having significantly delayed colonization relative to S. americanus and S. subaureus. In the single-species treatments, we found no significant differences in the dry biomasses of P. strobus seedlings colonized by each Suillus species, suggesting none was a more effective plant symbiont. Taken together, these results indicate that the rarity and anomalous host associations exhibited by S. subaureus in natural settings are not driven by inherently poor competitive ability or host growth promotion, but that the timing of colonization is a key factor determining the outcome of ectomycorrhizal fungal competitive interactions.
... Subsequent management practices, such as clear-cut logging, usually enhance these changes as a possible consequence of soil mechanical damage (Ford et al., 2018;Vašutová et al., 2018). The main driver of fungal community shifts is the death of mature trees Treu et al., 2014), because ECM fungi are obligate symbionts unable to live without their hosts (Baldrian, 2009;Lofgren et al., 2018). This results in an extinction of ECM fungal species associated with mature trees (= late-successional ECM fungi), while early-successional ECM fungi, with a low demand on photosynthates, survive on seedlings (Egli et al., 2002;Vašutová et al., 2018;Veselá et al., 2019b). ...
... On the other hand, almost all host tree species harbor in their symbiotic fungal assembly genusrestricted ECM fungi, which provide them exclusive access to resources (Molina et al., 1992). Nevertheless, ECM fungi with a broad host range may also show host preference depending on the ecological context (Lang et al., 2011), while genus-restricted ECM fungi may expand their host range in the absence of their primary host (Lofgren et al., 2018). ...
... Subsequent management practices, such as clear-cut logging, usually enhance these changes as a possible consequence of soil mechanical damage (Ford et al., 2018;Vašutová et al., 2018). The main driver of fungal community shifts is the death of mature trees Treu et al., 2014), because ECM fungi are obligate symbionts unable to live without their hosts (Baldrian, 2009;Lofgren et al., 2018). This results in an extinction of ECM fungal species associated with mature trees (= late-successional ECM fungi), while early-successional ECM fungi, with a low demand on photosynthates, survive on seedlings (Egli et al., 2002;Vašutová et al., 2018;Veselá et al., 2019b). ...
... On the other hand, almost all host tree species harbor in their symbiotic fungal assembly genusrestricted ECM fungi, which provide them exclusive access to resources (Molina et al., 1992). Nevertheless, ECM fungi with a broad host range may also show host preference depending on the ecological context (Lang et al., 2011), while genus-restricted ECM fungi may expand their host range in the absence of their primary host (Lofgren et al., 2018). ...
Article
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Due to ongoing climate change, forests are expected to face significant disturbances more frequently than in the past. Appropriate management is intended to facilitate forest regeneration. Because European temperate forests mostly consist of trees associated with ectomycorrhizal (ECM) fungi, understanding their role in these disturbances is important to develop strategies to minimize their consequences and effectively restore forests. Our aim was to determine how traditional (EXT) and nonintervention (NEX) management in originally Norway spruce (Picea abies) forests with an admixture of European larch (Larix decidua) affect ECM fungal communities and the potential to interconnect different tree species via ECM networks 15 years after a windstorm. Ten plots in NEX and 10 plots in EXT with the co-occurrences of Norway spruce, European larch, and silver birch (Betula pendula) were selected, and a total of 57 ECM taxa were identified using ITS sequencing from ECM root tips. In both treatments, five ECM species associated with all the studied tree species dominated, with a total abundance of approximately 50% in the examined root samples. Because there were no significant differences between treatments in the number of ECM species associated with different tree species combinations in individual plots, we concluded that the management type did not have a significant effect on networking. However, management significantly affected the compositions of ECM symbionts of Norway spruce and European larch but not those of silver birch. Although this result is explained by the occurrence of seedlings and ECM propagules that were present in the original forest, the consequences are difficult to assess without knowledge of the ecology of different ECM symbionts.
... A distinguishing feature of the ECM fungal lifestyle relative to other types of mycorrhizal interactions is the presence of highly host-specific associations Bruns et al., 2002). One of the best documented examples is the ECM fungal genus Suillus, which forms nearly exclusive associations with trees in the family Pineaceae (Kretzer et al., 1996;Lofgren et al., 2018). These associations are tightly coupled, with a given Suillus species forming specialized associations with a single host genus (particularly the genera Pinus, Larix and Pseudotsuga), and even with different subgenera within the genus Pinus (Kretzer et al., 1996;Liao et al., 2016). ...
... However, numerous examples have indicated bidirectional transitions between generalist and specialist lineages, and it is now accepted that high host specificity is neither universally derived nor an innately optimized resource acquisition strategy (Appel & Martin, 1992;Desdevises et al., 2002;Stireman, 2005;Hardy & Otto, 2014;Ouvrard et al., 2015). Our analyses included one example of a Suillus species capable of colonizing multiple host genera: Suillus subaureus is known to colonize white pine, larch and oak (Lofgren et al., 2018). Our ancestral state reconstruction supports an evolutionary trajectory where S. subaureus was derived from white pine-associated ancestors, making its ability to colonize multiple host groups an example of host expansion. ...
Article
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While there has been significant progress characterizing the ‘symbiotic toolkit’ of ectomycorrhizal (ECM) fungi, how host specificity may be encoded into ECM fungal genomes remains poorly understood. We conducted a comparative genomic analysis of ECM fungal host specialists and generalists, focusing on the specialist genus Suillus. Global analyses of genome dynamics across 46 species were assessed, along with targeted analyses of three classes of molecules previously identified as important determinants of host specificity: small secreted proteins (SSPs), secondary metabolites (SMs) and G‐protein coupled receptors (GPCRs). Relative to other ECM fungi, including other host specialists, Suillus had highly dynamic genomes including numerous rapidly evolving gene families and many domain expansions and contractions. Targeted analyses supported a role for SMs but not SSPs or GPCRs in Suillus host specificity. Phylogenomic‐based ancestral state reconstruction identified Larix as the ancestral host of Suillus, with multiple independent switches between white and red pine hosts. These results suggest that like other defining characteristics of the ECM lifestyle, host specificity is a dynamic process at the genome level. In the case of Suillus, both SMs and pathways involved in the deactivation of reactive oxygen species appear to be strongly associated with enhanced host specificity.
... Fungi encompass diverse trophic guilds (saprotrophs, pathogens and 43 mutualists) sustaining forest ecosystem functioning. Saprotrophic and ectomycorrhizal fungi (EMF) are 44 vital for nitrogen (N) and phosphorus (P) availability for plant growth, and strongly contribute to shape 45 humus forms (Ponge, 2003 Few studies have assessed the impact of tree species substitution on soil fungal community richness, and most of them compare fungal communities in adjacent stands of different tree species without 48 accounting for the potential legacy effects of the pre-substitution tree species (Lofgren et al., 2018). 49 ...
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Tree species risk living outside their ecological niche due to climate change. Assisted tree migration is proposed as an adaptive strategy, but its impact on forest biodiversity remains unclear. This study examines soil fungal diversity responses to tree species substitution and its underlying mechanisms. Three substitution treatments were tested across 69 stands in Northern France: (1) from mature Fagus sylvatica to young Quercus petraea, (2) from mature Pinus sylvestris to young P. nigra subsp. Laricio, and (3) from mature P. sylvestris to young Q. rubra. Holorganic and organo-mineral horizons were sampled to assess Ascomycota and Basidiomycota species richness with eDNA metabarcoding. Tree species identity was translated into trait values along the plant economic spectrum. Structural Equation Models (SEM) were used to separate the effects of tree traits, stand age, basal area and tree diversity on fungal diversity across four pathways: (1) stand structure, (2) edaphic humidity, (3) plant understorey, and (4) humipedon. After 25 years, Ascomycota and Basidiomycota richness did not respond to substitution treatments. SEM analyses showed that Basidiomycota richness in the organo-mineral horizon correlated positively with acquisitive tree species. Ascomycota richness was negatively linked to dominant understorey cover, following canopy openness and humipedon horizonation. In the organo-mineral horizon, Ascomycota richness increased with root nitrogen and wood density, spontaneous tree diversity and was favoured by reduced basal area related to stand rejuvenation. Forest management that promotes spontaneous tree diversity and reduces basal area could enhance Ascomycota richness in both horizons, mitigating the impacts of tree rejuvenation and species change.
... and S2). Host preference is generally low at the generic level (Lofgren et al., 2018), including in Nothofagus (Nouhra et al., 2013). Nevertheless, our correlations are based on common fungal taxa, while host tree identity can have greater effects on rare symbiont species . ...
Article
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Subantarctic Nothofagus forests are the southernmost forests in the world, with negligible atmospheric nitrogen (N) deposition. Most paradigms about the role of ectomycorrhizal (ECM) fungi in N cycling and plant N uptake at high latitudes have been tested in boreal coniferous forests, while in the southern hemisphere, ECM hosts are primarily angiosperms. Using ITS1 meta‐barcoding, we characterized ECM and saprotrophic fungal communities in evergreen and deciduous Nothofagus forests forming monodominant and mixed stands in the archipelago of Tierra del Fuego (Chile and Argentina). We assessed the N economy of Nothofagus by correlating host species with fungal relative abundances, edaphic variables, net N mineralization, microbial biomass N and the activity of eight extracellular soil enzymes activities. The N economy of deciduous N. pumilio forests was strikingly similar to boreal coniferous forests, with the lowest inorganic N availability and net N mineralization, in correlation to higher relative abundances of ECM fungi with enzymatic capacity for organic N mobilization (genus Cortinarius). In contrast, the N economy of evergreen N. betuloides forests was predominantly inorganic and correlated with ECM lineages from the family Clavulinaceae, in acidic soils with poor drainage. Grassy understory vegetation in deciduous N. antarctica forests likely promoted saprotrophic fungi (i.e., genus Mortierella) in correlation with higher activities of carbon‐degrading enzymes. Differences between Nothofagus hosts did not persist in mixed forests, illustrating the range of soil fertility of these ECM angiosperms and the underlying effects of soil and climate on Nothofagus distribution and N cycling in southern Patagonia.
... Because a single EM tree can support a rich community of EM fungi (Bahram et al., 2011;Branco et al., 2013), even one isolated EM tree surrounded by AMdominated forest has the potential to function as a reservoir of EM fungal diversity. Apart from accumulations of EM fungal propagules in the soil (Borchers & Perry, 1990;, EM patches can support active EM fungal mycelium that may enhance EM colonisation and establishment of seedlings Lofgren et al., 2018;Nara, 2006b;Thiet & Boerner, 2007). These mycorrhizal networks may enhance seedling establishment through rapid inoculation of roots and increases in the seedling's zone of interaction with the soil, but not necessarily through direct nutrient transfer between hosts (Henriksson et al., 2023;Newman, 1988;van der Heijden & Horton, 2009). ...
Article
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Deciduous forests in northeastern North America are comprised of a mixture of ectomycorrhizal (EM) and arbuscular mycorrhizal (AM) trees. However, land use legacies and other factors have decreased EM and concomitantly increased AM tree dominance, potentially limiting forest ecosystem functioning. We investigated how scattered EM tree patches and soil inoculum from local EM tree‐dominated forests influence EM fungal colonisation, survival and growth of EM Tsuga canadensis, Pinus strobus and Quercus spp. tree seedlings in AM‐dominated secondary forests. Seedlings were planted next to dominant AM Acer and scattered EM Betula trees across three New York secondary forests. A subset of seedlings also received soil inoculum from local EM‐dominated forests. We monitored the survival and height growth of seedlings for 2 years and then measured seedling shoot biomass, assessed EM colonisation and identified EM fungi from seedling roots. All genera of seedlings planted near EM Betula had higher EM colonisation and fungal richness than those planted near AM Acer trees. Inoculation with EM forest soil increased EM colonisation and fungal richness of seedlings only near AM Acer, showing great effectiveness in areas lacking native EM fungi. Total EM fungal diversity on seedling roots was highest near EM Betula, which included numerous taxa usually associated with mature trees. In contrast, EM fungal communities near AM Acer were sparse and mostly dominated by relatively few taxa of spore‐bank fungi. Although seedling survival did not differ between treatments, soil inoculation and proximity to EM Betula increased second‐year height growth of Pinus and Tsuga while soil inoculation alone significantly enhanced shoot mass of Quercus seedlings. Synthesis. Agricultural land use legacies have resulted in expansive secondary forests dominated by AM trees. In these forests, establishment of EM tree seedlings outside existing EM tree patches may be hindered by a lack of EM fungi, but local soil inoculum from EM tree‐dominated forests can reintroduce native EM fungi into secondary forests lacking established EM trees.
... Colonización de raíces por la comunidad de ECM en plantas de vivero La mayor velocidad de colonización de raíces y micorrización de plantas por efecto de la comunidad de ECM y procedencia de la semilla de Cieneguilla en los primeros ocho meses del bioensayo refleja diferencias adaptativas de la comunidad de ECM, asociadas con las condiciones ambientales de las localidades. Es común que en sitios con ambientes limitantes las especies desarrollen como mecanismos de supervivencia estrategias de tipo ruderal para colonizar el área (Ding et al., 2011;Lofgren et al., 2018). La mayor velocidad de colonización de la comunidad de ECM de Cieneguilla se asocia con la capacidad de invasión que poseen algunas especies para colonizar plántulas a partir de hifas (Peay et al., 2010;Ding et al., 2011). ...
Article
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Background and Aims: The compatibility between mycorrhizal fungi and trees is a consequence of coevolutionary processes in response to selection pressures. The diversity and differentiation of morphotypes from ectomycorrhizal fungi (ECM) communities in natural populations of Pinus greggii var. australis were analyzed in two contrasting environments (Zacualpan and Cieneguilla, Mexico), and in reciprocal combinations of seed and inoculum origin in the nursery. Methods: Soil samples were collected from two natural populations of P. greggii var. australis. A portion of the samples was used to obtain and identify mycorrhizal morphotypes, and the other was used as inoculum for the nursery bioassay. Shannon diversity index and Bray-Curtis similarity index were used to estimate diversity and differentiation degree of ECM communities in both natural populations and in seedlings from the nursery bioassay. Key results: Thirty-two different ECM morphotypes were found in the natural populations, 23 in Zacualpan, 17 in Cieneguilla, and eight in both of them. ECM morphotypes diversity was higher in Zacualpan, with a strong differentiation from the other community. At the beginning of the bioassay, Tomentella sp. was the dominant morphotype, but after eight months it was Rhizopogon sp. Cenoccocum geophilum and Wilcoxina sp. morphotypes were also identified. Root colonization dynamics was faster with the Cieneguilla origin for either guest or host. ECM diversity was higher in the sympatric associations at the beginning, but 12 months after sowing it was higher in the allopatric ones. Conclusions: A high diversity and strong differentiation in ECM morphotypes was found in two natural P. greggii var. australis populations. However, diversity and differentiation of the ECM community morphotypes in the bioassay decreased with age of seedlings, indicating an effect of the nursery environment in homogenizing the composition of the ECM community. Key words: allopatry, coevolution, ectomycorrhizal fungi, sympatry.
... For example, several EcM fungal taxa inferred to be specific turned out to be nonspecific in situations where host plants co-occur with non-hosts (i.e., neighbourhood effect; Bogar & Kennedy, 2013) or when EcM host plants become locally extinct (Toftegaard et al., 2010;Perez-Pasos et al., 2021). In some of these occasions, such 'untypical' symbiosis is physiologically efficient enough to allow fungi produce fruiting bodies (Lofgren et al., 2018). While partner specificity is relatively well documented for EcM macrofungi, much less is known about other groups, especially the fungal taxa that produce inconspicuous or no fruiting bodies (Põlme et al., 2018). ...
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Partner specificity is a well‐documented phenomenon in biotic interactions, yet the factors that determine specificity in plant‐fungal associations remain largely unknown. By utilizing composite soil samples, we identified the predictors that drive partner specificity in both plants and fungi, with a particular focus on ectomycorrhizal associations. Fungal guilds exhibited significant differences in overall partner preference and avoidance, richness, and specificity to specific tree genera. The highest level of specificity was observed in root endophytic and ectomycorrhizal associations, while the lowest was found in arbuscular mycorrhizal associations. The majority of ectomycorrhizal fungal species showed a preference for one of their partner trees, primarily at the plant genus level. Specialist ectomycorrhizal fungi were dominant in belowground communities in terms of species richness and relative abundance. Moreover, all tree genera (and occasionally species) demonstrated a preference for certain fungal groups. Partner specificity was not related to the rarity of fungi or plants or environmental conditions, except for soil pH. Depending on the partner tree genus, specific fungi became more prevalent and relatively more abundant with increasing stand age, tree dominance, and soil pH conditions optimal for the partner tree genus. The richness of partner tree species and increased evenness of ectomycorrhizal fungi in multi‐host communities enhanced the species richness of ectomycorrhizal fungi. However, it was primarily the partner‐generalist fungi that contributed to the high diversity of ectomycorrhizal fungi in mixed forests.
... However, it is important to consider the species-specific dynamics of mycorrhizal formation. For example, the genus Suillus shows rapid ectomycorrhizal formation in pine trees, which emphasizes the importance of protecting seedling roots during the early stages in the nursery [167]. ...
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In the latest literature, climate models show that the conditions for pines, spruces, larches, and birches will deteriorate significantly. In Poland, as well as in other European countries, there are already signs of the decline of these species. This review article deals with the symbiotic relationships between fungi and plants, which can hardly be overestimated, using the example of pine trees. These are the oldest known symbiotic relationships, which are of great benefit to both components and can help plants, in particular, survive periods of severe drought and the attack of pathogens on the roots. This article describes symbioses and their causal conditions, as well as the mycorrhizal components of pine trees and their properties; characterizes ectomycorrhizal fungi and their mushroom-forming properties; and provides examples of the cultivation of pure fungal cultures, with particular attention to the specificity of the mycorrhizal structure and its effects on the growth and development of Pinus species. Finally, the role of mycorrhiza in plant protection and pathogen control is described.
... Compared with PM, CE, and KC, CC and CF mainly affect microbial diversity in terms of three aspects. First, Fagaceae generally have an extensive production of fine roots than a Pinaceae plant [32], which may provide more rhizosphere areas to accommodate microbes, thus supporting diverse community characteristics. Therefore, CC and CF may have more fine roots than PM and KC, which leads to higher microbial diversity. ...
Article
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To explore the contribution of microorganisms to forest ecosystem function, we studied the ectomycorrhizal (ECM) fungal and soil bacterial community of the five typical tree species (Pinus massoniana, PM; Castanopsis carlesii, CC; Castanopsis eyrei, CE; Castanopsis fargesii, CF; and Keteleeria cyclolepis, KC) at the Junzifeng National Nature Reserve. The results indicated that the ECM fungal and soil bacterial diversity of CC and CF was similar, and the diversity rates of CC and CF were higher than those of PM, CE, and KC. Cenococcum geophilum and unclassified_Cortinariaceae II were the most prevalent occurring ECM fungi species in the five typical tree species, followed by unclassified_Cortinariaceae I and Lactarius atrofuscus. In bacteria, the dominant bacterial genera were Acidothermus, Bradyrhizobium, Acidibacter, Candidatus_Solibacter, Candidatus_Koribacter, Roseiarcus, and Bryobacter. EMF fungi and soil bacteria were correlated with edaphic factors, especially the soil pH, TP, and TK, caused by stand development. The results show that the community characteristics of ECM fungi and bacteria in the typical tree species of the Junzifeng National Nature Reserve reflect the critical role of soil microorganisms in stabilizing forest ecosystems.
... For EM fungi, more evidence for phylogenetic specificity has been reported. For example, EM fungal Suillus species almost exclusively associate with taxa from the plant family Pinaceae (Lofgren et al., 2018). Additionally, a considerable number of EM fungal taxa have strong indications of host specificity at both the family and genus levels and plant phylogeny is often one of the best predictors of EM community composition at regional scales (Molina et al., 1992;Miyamoto et al., 2022). ...
Article
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Species interactions exhibit varying degrees of specialization, ranging from generalist to specialist interactions. For many interactions (e.g., plant-microbiome) we lack standardized metrics of specialization, hindering our ability to apply comparative frameworks of specificity across niche axes and organismal groups. Here, we discuss the concept of plant host specificity of arbuscular mycorrhizal (AM) fungi and ectomycorrhizal (EM) fungi, including the predominant theories for their interactions: Passenger, Driver, and Habitat Hypotheses. We focus on five major areas of interest in advancing the field of plant-mycorrhizal fungal host specificity: phylogenetic specificity, host physiology specificity, functional specificity, habitat specificity, and mycorrhizal fungal-mediated plant rarity. Considering the need to elucidate foundational concepts of specificity in this globally important symbiosis, we propose standardized metrics and comparative studies to enhance our understanding. We also emphasize the importance of analyzing global mycorrhizal data holistically to draw meaningful conclusions and suggest a shift toward single-species analyses to unravel the complexities underlying these associations.
... This may also reflect the relationship between ectomycorrhizal species and their plant hosts (Hart et al., 2005;Rodríguez-Echeverría et al., 2016). As plant composition changes along the post-fire temporal axis and under differing fire frequencies Gosper et al., 2012;Pausas & Bradstock, 2007), ectomycorrhizal species that are host-specific (Lofgren et al., 2018) may undergo changes (Hart et al., 2005). Simultaneously, changes in ectomycorrhizal composition between time-since-fire ages and fire frequencies could have implications for plant productivity (Anthony et al., 2022), plant composition (Albornoz et al., 2016) and biogeochemical cycles (Averill & Hawkes, 2016;Zak et al., 2019) because ectomycorrhizal species vary in their nutrient acquisition abilities (Leake, 2001;Zak et al., 2019). ...
Article
Fire has shaped global ecosystems for millennia by directly killing organisms and indirectly altering habitats and resources. All terrestrial ecosystems, including fire-prone ecosystems, rely on soil-inhabiting fungi, where they play vital roles in ecological processes. Yet our understanding of how fire regimes influence soil fungi remains limited and our knowledge of these interactions in semiarid landscapes is virtually absent. We collected soil samples and vegetation measurements from sites across a gradient in time-since-fire ages (0-75 years-since-fire) and fire frequency (burnt 0-5 times during the recent 29-year period) in a semiarid heathland of south-eastern Australia. We characterized fungal communities using ITS amplicon-sequencing and assigned fungi taxonomically to trophic guilds. We used structural equation models to examine direct, indirect and total effects of time-since-fire and fire frequency on total fungal, ectomycorrhizal, saprotrophic and pathogenic richness. We used multivariate analyses to investigate how total fungal, ectomycorrhizal, saprotrophic and pathogenic species composition differed between post-fire successional stages and fire frequency classes. Time-since-fire was an important driver of saprotrophic richness; directly, saprotrophic richness increased with time-since-fire, and indirectly, saprotrophic richness declined with time-since-fire (resulting in a positive total effect), mediated through the impact of fire on substrates. Frequently burnt sites had lower numbers of saprotrophic and pathogenic species. Post-fire successional stages and fire frequency classes were characterized by distinct fungal communities, with large differences in ectomycorrhizal species composition. Understanding the complex responses of fungal communities to fire can be improved by exploring how the effects of fire flow through ecosystems. Diverse fire histories may be important for maintaining the functional diversity of fungi in semiarid regions.
... Thus, the section Scleroderma not only contains species without clamp connections, but also contains species with clamp connections. ECM fungi demonstrate various degrees of host specificity and certain fungal genera exhibit strong host specificity [46,47]. Compared to the other genera (e.g., Chroogomphus, Rhizopogon, and Suillus, which are specifically associated with the pine family), which exhibited strong mycorrhizal host specificity [46,48], Scleroderma exhibits less host specificity. ...
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The genus Scleroderma contains gasteroid basidiomycetes, which form globose spores with echinulate to reticulate ornamentation on the surface. Based on the morphological observations in combination with molecular data, four new species, S. erubescens, S. separatum, S. squamulosum, and S. vinaceum, were described from Yunnan, southwestern China. Images of fresh basidiomata and scanning electron microscope (SEM) images of basidiospores are provided. Phylogenetic analyses based on ITS sequences show that these four new taxa belong to the Scleroderma section Scleroderma.
... Host Dipterocarps were not symbiont speci c as mentioned in a previous study (Peay et al., 2015b). Dominance of certain ECM could be due to the different origins of host trees before they were planted or the historical legacy of ECM in parks (Lofgren et al., 2018). Before the trees were planted in parks, they could have also hosted the ECM from the nursery which continue to dominate in the parks (Stenström & Ek, 1990). ...
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Ectomycorrhizae (ECM) are important symbionts for multiple host plants. This study used morphology and DNA metabarcoding to identify ECM in Dipterocarpaceae, the dominant tree family of Southeast Asian forests. ECM fruiting bodies were first visually documented and identified across five urban parks in Singapore. Under host Dipterocarp Hopea odorata trees, 50 soil and root samples were collected. This was done together with another 50 root samples taken from ten species of host Dipterocarp seedlings at the Singapore Botanic Gardens’ Plant Resource Centre nursery. Eight genera of ECM were found in parks, one was identified to species level and three genera were only found from fungal Amplicon Sequence Variants (ASVs) using DNA metabarcoding. Although the nursery had more Dipterocarp species, only four genera of ECM were present. ECM communities differed slightly across host species, but not host genera. Tomentella spp. were the most common ECM found in parks and Dipterocarp seedlings.
... Although both petiole materials showed a similar continuous increase in total fungal DNA amount across the overwintering period, as measured by FungiQuant (Liu et al., 2012), the differential abundance and dynamics of ascomycetes and basidiomycetes between petioles from the healthy and diseased stands present challenges for comparing fungal biomass levels. Basidiomycetes tend to have larger genomes and higher copy numbers of rRNA gene cluster than ascomycetes (Lofgren et al., 2018). Additionally, the number of nuclei per cell can vary considerably between different species, from one to several dozen (e.g., James et al., 2008). ...
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Introduction The ascomycete Hymenoscyphus fraxineus, originating from Asia, is currently threatening common ash (Fraxinus excelsior) in Europe, massive ascospore production from the saprotrophic phase being a key determinant of its invasiveness. Methods To consider whether fungal diversity and succession in decomposing leaf litter are affected by this invader, we used ITS-1 metabarcoding to profile changes in fungal community composition during overwintering. The subjected ash leaf petioles, collected from a diseased forest and a healthy ash stand hosting the harmless ash endophyte Hymenoscyphus albidus, were incubated in the forest floor of the diseased stand between October 2017 and June 2018 and harvested at 2–3-month intervals. Results Total fungal DNA level showed a 3-fold increase during overwintering as estimated by FungiQuant qPCR. Petioles from the healthy site showed pronounced changes during overwintering; ascomycetes of the class Dothideomycetes were predominant after leaf shed, but the basidiomycete genus Mycena (class Agaricomycetes) became predominant by April, whereas H. albidus showed low prevalence. Petioles from the diseased site showed little change during overwintering; H. fraxineus was predominant, while Mycena spp. showed increased read proportion by June. Discussion The low species richness and evenness in petioles from the diseased site in comparison to petioles from the healthy site were obviously related to tremendous infection pressure of H. fraxineus in diseased forests. Changes in leaf litter quality, owing to accumulation of host defense phenolics in the pathogen challenged leaves, and strong saprophytic competence of H. fraxineus are other factors that probably influence fungal succession. For additional comparison, we examined fungal community structure in petioles collected in the healthy stand in August 2013 and showing H. albidus ascomata. This species was similarly predominant in these petioles as H. fraxineus was in petioles from the diseased site, suggesting that both fungi have similar suppressive effects on fungal richness in petiole/rachis segments they have secured for completion of their life cycle. However, the ability of H. fraxineus to secure the entire leaf nerve system in diseased forests, in opposite to H. albidus, impacts the general diversity and successional trajectory of fungi in decomposing ash petioles.
... In mycorrhizal systems, a single mycorrhizal plant typically associates with several fungal species simultaneously, and fungal species are rarely restricted to a single-host type (van der Heijden et al., 2015). However, evidence is emerging that many ectomycorrhizal fungal species show some level of host preference, especially to different host genera or families (Tedersoo et al., 2008;Bahram et al., 2012;Lofgren et al., 2018;van der Linde et al., 2018;Carriconde et al., 2019). This contrasts with arbuscular mycorrhizal fungi that are often host generalists (Smith & Read, 2008). ...
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Mechanisms of diversification in fungi are relatively poorly known. Many ectomycorrhizal symbionts show preference for particular host genera or families, so host–symbiont selection may be an important driver of fungal diversification in ectomycorrhizal systems. However, whether ectomycorrhizal hosts and symbionts show correlated evolutionary patterns remains untested, and it is unknown whether fungal specialisation also occurs in systems dominated by hosts from the same genus. We use metabarcoding of ectomycorrhizal fungi collected with hyphal ingrowth bags from Nothofagus forests across southern New Zealand to investigate host–symbiont specialisation and correlated evolution. We examine how ectomycorrhizal communities differ between host species and look for patterns of host–symbiont cophylogeny. We found substantial differences in ectomycorrhizal communities associated with different host taxa, particularly between hosts from different subgenera (Lophozonia and Fuscospora), but also between more closely related hosts. Twenty‐four per cent of fungal taxa tested showed affiliations to particular hosts, and tests for cophylogeny revealed significant correlations between host relatedness and the fungal phylogeny that extended to substantial evolutionary depth. These results provide new evidence of correlated evolution in ectomycorrhizal systems, indicating that preferences among closely related host species may represent an important evolutionary driver for local lineage diversification in ectomycorrhizal fungi.
... Since plants actively alter the soil microbiome to their benefit in a species-specific way (Huang et al. 2019), aboveground biological invasions also impact the underground. Specifically, for ECMs, interactions between native plants and exotic fungi do not necessarily cease after the removal of exotic plant species (Lofgren et al. 2018), and this fact adds an unknown competition problem between native and introduced fungi. ...
Chapter
Soil is one of the main reservoirs of biodiversity on earth due to its physical, chemical, and microclimatic heterogeneity; in particular, it harbors a great diversity of microbial communities. Changes in land uses for crop production, mainly those that involve intense agricultural management, threaten soil diversity, compromising global ecosystem functioning and services. In this chapter, we give an up-to-date overview of the effect of two no-till agricultural practices (crop rotation (CR) versus soybean monocropping (MC)) on arbuscular mycorrhizal fungi (AMF) communities by gathering our data of five geographical locations of East-Central Argentina. The diversity was described considering AMF classification and functioning based on the morphological traits and ontogeny of spores. In addition, we analyzed our data considering three taxonomic categories: morphospecies, families, and orders. Fifty-nine AMF morphospecies were identified throughout the five geographical locations, and CR soils showed the highest AMF richness and spore density and the lowest evenness. Funneliformis mosseae and Glomus sp.4 morphospecies and Glomerales were significant indicators for CR. For MC, Acaulosporaceae and Diversisporales were significant indicators. Soil variables influenced the relative abundance of AMF depending on the family and order. Percentage of organic carbon and nitrogen was positively associated with CR and negatively with MC. Overall, no-till agricultural practices showed differences in their soil AMF communities and chemical properties, and management systems that include practices based on CR promote greater richness of AMF morphospecies.KeywordsGlomeromycotina Agroecosystems Taxonomic groups Morphospecies Land uses
... Since plants actively alter the soil microbiome to their benefit in a species-specific way (Huang et al. 2019), aboveground biological invasions also impact the underground. Specifically, for ECMs, interactions between native plants and exotic fungi do not necessarily cease after the removal of exotic plant species (Lofgren et al. 2018), and this fact adds an unknown competition problem between native and introduced fungi. ...
Chapter
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Currently, effective ecological restoration of degraded ecosystems and the reduction of gas emissions have been considered solutions to mitigate and counteract the negative effects of climate change. Moreover, mycorrhizas are currently widely recognized as fundamental components of plant communities and key modulators of ecosystem functioning. Consequently, it is highly important to consider the mycorrhizal symbiosis in the context of effective ecological restoration. Evidence mostly from the northern hemisphere shows that using mycorrhizas in field experiments of restoration has positive effects on plant biomass as well as in community richness. The experiments from South America are scarce and come exclusively from Venezuela, Brazil, Argentina, and Chile, most of them showing positive effects on plant performance. The field experiments of ecological restoration from South America use mainly arbuscular mycorrhizal symbiosis, with one exception for ectomycorrhizas; however, there is no evidence of the effects on the use of orchid and ericoid mycorrhizas. It is highlighted running experiments from Brazil with ectomycorrhizas and, certainly, future research questions in field settings within ecological restoration contexts should consider orchid and ericoid mycorrhizas.KeywordsRestoration ecologyGlobal changeClimate changeMycorrhizal fungi
... Since plants actively alter the soil microbiome to their benefit in a species-specific way (Huang et al. 2019), aboveground biological invasions also impact the underground. Specifically, for ECMs, interactions between native plants and exotic fungi do not necessarily cease after the removal of exotic plant species (Lofgren et al. 2018), and this fact adds an unknown competition problem between native and introduced fungi. ...
Chapter
Dipterocarpaceae is an important family of trees in Paleotropics that form ectomycorrhizal (EcM) symbiosis. In 1995, a Neotropical species, Pseudomonotes tropenbosii, was found in the Amazonian region in Colombia. Due to the EcM association of multiple species of dipterocarp trees in Asia and Africa, we hypothesized that P. tropenbosii might have EcM symbionts as well. In this study, 90 species of EcM fungi of P. tropenbosii were documented from aboveground/sporocarps (79 spp.) and belowground/root-tip samples (2 spp.). The EcM fungal community was dominated by the genera Clavulina (13 species), Russula (9 species), and Craterellus, Coltricia, and Cortinarius (6 species each). Differences in the diversity and richness of species across sites were found, independent of the abundance of P. tropenbosii and the proximity of the sites, suggesting that environmental differences among sites are important in structuring the EcM fungal communities. About half of the ECM fungal species of P. tropenbosii coexisted with species of Fabaceae and Pakaraimae dipterocarpacea (Cistaceae) occurring in geographically remote neotropical lowland rainforests. Noteworthy is the diversity of Clavulina found that is represented by 12 species of which 9 were described from Fabaceae-dominant forests in Guyana, unraveling a broad host diversity and widespread distribution of these EcM fungi. The EcM status of P. tropenbosii suggests that a Gondwana ancestor of the Dipterocarpaceae already presented the mutualistic relationship with EcM fungal taxa; however boreotropical migration or transatlantic dispersal has been also proposed, but this remains debated. More research is needed to fully understand the distribution patterns of EcM fungi in this tropical region and their role in nutrient cycling, including carbon sequestration, and its importance for plant distribution.
... It is well-known that the proximity of trees of different species affects the community compositions of EcMf, although host identity is likely to be the primary factor used to select symbionts (e.g., Nara 2006;Bogar et al., 2013). For example, Lofgren et al. (2018) indicated that Pinaceae-specific Suillus subaureus could colonize Quercus hosts under conditions where Pinaceae-hosts were co-planted. Such neighborhood effects may be one of the factors that increase the rate of shared OTUs and the similarity of OTU compositions between Sakhalin fir seedlings and surrounding broadleaved trees in the retention sites. ...
Article
We have examined the effects of dispersed and aggregated retention on the diversity of root-associated ectomycorrhizal fungi (EcMf) in Sakhalin fir (Abies sachalinensis) plantations, 4 years after logging. Roots of Sakhalin fir seedlings and the adjacent broadleaved or Sakhalin fir trees were sampled in broadleaved dispersed retention sites (10, 50, or 100 trees/ha), conifer aggregated retention sites (a single 60 × 60 m square patch of Sakhalin fir trees per site), clear-cut sites, unharvested Sakhalin fir plantations, and natural broadleaved forest stands. The EcMf on the roots were grouped into operational taxonomic units based on the similarity of the internal transcribed spacer sequences within the nuclear ribosomal DNA. Clear-cutting significantly reduced the species richness and diversity of the EcMf and altered the species composition when compared with the unharvested Sakhalin fir plantations and natural broadleaved forests. In contrast, both the aggregated and dispersed retention sites maintained higher levels of EcMf diversity, as well as different EcMf communities when compared with the clear-cut sites. Aggregated retention was effective at conserving EcMf diversity at the unharvested Sakhalin fir plantations, but the effects were limited within retained patches. Broadleaved dispersed retention did not retain the EcMf communities that were present prior to logging even at high retention levels, but they could retain unique EcMf communities, which differed between the Sakhalin fir plantations, natural broadleaved forests, and clear-cut sites. The species richness and diversity values for some of the dispersed retention sites were comparable to the values for the unharvested Sakhalin fir plantations and tended to be greater than the values for the aggregated retention sites. The results indicate that dispersed retention could be an effective strategy by which to preserve a larger number of EcMf species and unique EcMf communities in logged conifer plantations, although the positive effects were likely limited spatially within the rooting zones of the retained broadleaved trees. Finally, naturally regenerating Sakhalin fir seedlings were found to share a large amount of their EcMf with adjacent broadleaved retention trees, indicating that multi-host EcMf of retained trees largely contribute to ectomycorrhizal colonization of the surrounding regenerated seedlings in the logged areas. Our findings demonstrated that both dispersed and aggregated retention methods could be used to mitigate the impacts of logging on EcMf diversity in Sakhalin fir plantations, in Japan, and that there were large differences in the effects among the different retention methods.
... While many host-mycorrhizal associations have evolved to be highly specific (Bruns et al. 2002), for mycorrhizal networks to emerge in a diverse forest system, the interaction among host trees and their mycorrhizal partners requires both the host and the fungi to expand their compatibility. From the host point of view: Suillus species, known to exhibit high host specificity, have been shown to associate with both their classical Pinaceae host and other, less traditional hosts, like Quercus, only in the presence of a co-planted Pinaceae host (Lofgren et al. 2018). In addition, dual-mycorrhizal plants can switch between EMF and AMF mycorrhizal mutualists under a wide range of biotic and abiotic conditions were characterized (Teste et al. 2020). ...
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Mechanisms of host-microbe interactions and their direct impact on both parties have been extensively researched, however, much less is known on the effect of these interactions on the ecology of the host-community. Here we investigate tree-fungi mycorrhizal interactions, focusing on mycorrhizal-meditated resource sharing among trees, while examining the dynamics between specialist and generalist fungi and their implications on the forest ecology. Using genetic meta-barcoding, we identified the fungal community colonizing different trees in a mixed forest, and generated an extensive mapping connecting fungal sequences to their tree hosts. The mycorrhizal fungal community diverged between ectomycorrhizal and arbuscular host trees, but, unexpectedly, multiple ectomycorrhizal species colonized roots of non-ectomycorrhizal host trees. We complemented these findings by a novel computational framework, modeling competition between generalist and specialist mycorrhizal fungi, accounting for fungal-mediated resource sharing among neighboring trees. The analysis of the model revealed that generalist mycorrhizal networks may affect the entire tree community, and contribute to the maintenance of forest diversity in the long run. Furthermore, higher initial spatial mixing of trees can promote the evolution of generalist mycorrhizal species. These novel belowground interactions among trees and fungi may significantly impact forest biodiversity.
... An ecological difference can serve as a taxonomic character to distinguish novel species. Although the host preference/specificity of mycorrhizal fungi is complex and needs both field surveys and in vitro mycorrhizal synthesis assays using mycelia and basidiospores to evaluate accurately (Lofgren et al., 2018; Pérez-Pazos et al., 2021), our observations and molecular analyses of mycorrhizae demonstrated that S. flavorhizomorphae prefers pines whereas S. chloroporum prefers broadleaved trees in Betulaceae (Carpinus) and Fagaceae (Castanopsis and Quercus). This suggests that different species in this genus have different host preferences. ...
Article
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We describe two new species of resupinate Sistotrema sensu lato (Cantharellales) collected in Japan: S. flavorhizomorphae and S. chloroporum. Both species have urniform basidia with more than four sterigmata and monomitic hyphal system, oil-rich hyphae in subiculum, which is typical for this genus. Sistotrema chloroporum is characterized by poroid hymenophore partly yellowish-green, basidia 4-6-spored, medium-sized basidiospores (4.5-6.5 × 3.5-6 µm), and broadleaf forest habitat. Sistotrema flavorhizomorphae is characterized by hydnoid-irpicoid hymenophore, bright yellowish rhizomorphs, basidia 6-8-spored, small basidiospores (3-3.5 × 2.5-3 µm), and pine forest habitat. Phylogenetic trees inferred from the fungal nrDNA ITS and LSU and the rpb2 sequences supported that both species were distinct and grouped with other ectomycorrhizal Sistotrema and Hydnum species, but their generic boundary was unclear. Mycorrhizae underneath basidiomes of both species were identified and described via molecular techniques. Mycorrhizae of S. chloroporum have similar characteristics to those of other Sistotrema s.l. and Hydnum species, i.e., S. confluens and H. repandum, whereas S. flavorhizomorphae has a distinct morpho-anatomy, for example, a distinct pseudoparenchymatous mantle. Comprehensive characterizations of basidiomes and mycorrhizae improve the taxonomic analysis of mycorrhizal species of Sistotrema s.l.
... For example, the Larix specialist Suillus larcinus was detected on a Betula sapling when growing next to a Larix sapling(Nara, 2006).In another study it was shown that Suillus subaureus can germinate and associate with both Pinus and Quercus hosts, both in the laboratory and in the forest. Two other fungi, Suillus americanus and Suillus clintonianus, germinated by spores only in the presence of their primary Pinus hosts but could also form mycorrhizal association with Quercus and Larix trees when colonizing via mycelial networks(Lofgren et al., 2018). ...
Article
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Mycorrhizal fungi can colonize multiple trees of a single or multiple taxa, facilitating bidirectional exchange of carbon between trees. Mycorrhiza‐induced carbon transfer was shown in the forest, but it is unknown whether carbon is shared symmetrically among tree species, and if not, which tree species are better donors and which are better recipients. Here we test this question by investigating carbon transfer dynamics among five Mediterranean tree species in a microcosm system, including both ectomycorrhizal (EM) and arbuscular (AM) plants. Trees were planted together in 'community boxes' using natural soil from a mixed forest plot that serves as habitat for all five tree species and their native mycorrhizal fungi. In each box, only the trees of a single species were pulse‐labeled with 13CO2. We found that carbon transfer was asymmetric, with oak being a better donor, and pistacia and cypress better recipients. Shared mycorrhizal species may have facilitated carbon transfer, but their diversity did not affect the amount, nor timing, of the transfer. Overall, our findings in a microcosm system expose rich, but hidden, belowground interactions in a diverse population of trees and mycorrhizal fungi. The asymmetric carbon exchange among co‐habiting tree species could potentially contribute to forest resilience in an uncertain future.
... Host associations with both subgenera of Pinus are reported for S. flavidus and S. acidus but should be further verified. For the North American S. subaureus, an initial association with Pinus subgenus Strobus is required for transferring into Quercus in later developmental stage, therefore Quercus was not included in the BayesTraits analysis (Lofgren et al., 2018). Further, Suillus sinuspaulianus was also excluded from the host reconstruction due to the uncertainty of its host association (Pomerleau and Smith, 1962;Kretzer et al., 1996). ...
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Suillus is a genus of ectomycorrhizal fungi associated almost exclusively with Pinaceae. Lack of sample collections in East Asia and unresolved basal phylogenetic relationships of the genus are the major obstacles for better understanding the Suillus evolution. A resolved phylogeny of Suillus representing global diversity was achieved by sequencing multiple nuclear ribosomal and protein coding genes and extensive samples collected in East Asia. Fungal fossils are extremely rare, and the Eocene ectomycorrhizal symbiosis (ECM) fossil of Pinus root has been widely used for calibration. This study explored an alternative calibration scenario of the ECM fossil for controversy. Ancestral host associations of Suillus were estimated by maximum likelihood and Bayesian Markov chain Monte Carlo (MCMC) analyses, inferred from current host information from root tips and field observation. Host shift speciation explains the diversification of Suillus major clades. The three basal subgenera of Suillus were inferred to be associated with Larix, and diverged in early Eocene or Upper Cretaceous. In the early Oligocene or Paleocene, subgenus Suillus diverged and switched host to Pinus subgenus Strobus, and then switched to subgenus Pinus four times. Suillus subgenus Douglasii switched host from Larix to Pseudotsuga in Oligocene or Eocene. Increased species diversity occurred in subgenus Suillus after it switched host to Pinus but no associated speciation rate shifts were detected. Ancestral biogeographic distributions of Suillus and Pinaceae were estimated under the Dispersal Extinction Cladogenesis (DEC) model. Ancestral distribution patterns of Suillus and Pinaceae are related but generally discordant. Dispersals between Eurasia and North America explain the prevalence of disjunct Suillus taxa.
... supervivencia dependen de estos hongos, cuya falta podría conducir al fracaso de las plantaciones de pinos (Barragán et al., 2018;Lofgren et al., 2018;López et al., 2018;Ning et al., 2019). La presencia abundante y diversa de los hongos ectomicorrízicos en suelos pobres de nutrientes sugiere que éstos optimizarían la nutrición de las plantas, la absorción de agua, la resistencia a diferentes condiciones de estrés, protección contra patógenos de las raíces y contribuirían al mantenimiento de bosques tropicales monodominantes (García et al., 2017a;Hortal et al., 2017;Torres et al., 2017;Corrales et al., 2018;Albornoz et al., 2020;Liang et al., 2020;Liu et al., 2020). ...
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Se evaluó el efecto de Scleroderma verrucosum (Vaill) Pers y Rhizopogon luteolus Fr. & Nordh. sobre la calidad morfológica y biológica de plantas de Pinus radiata D. Don en vivero en Vilcashuamán, Ayacucho, Perú. Tratamientos: (1) Micorrización con Scleroderma verrucosum, (2) Micorrización con Rhizopogon luteolus, (3) Mezcla de ambos hongos y (4) Control, en un diseño completamente al azar con 10 repeticiones por tratamiento. Los hongos provinieron de bosques de Pinus radiata y Eucalyptus globulus de la localidad. La inoculación se realizó en el repique a los 30 días de siembra y la evaluación a los 7.5 meses después del repique. Los pinos micorrizados superaron con diferencias significativas al control en todas las variables. En el diámetro del cuello y materia seca de la parte aérea de los inoculados no presentaron diferencias significativas; sin embargo, en altura, materia seca de la raíz y materia seca total destacó el tratamiento Mezcla. En la calidad biológica se observó mayor número de micorrizas en los inoculados, con diferencias significativas frente al control sin micorrizar. Se evidenció mayor porcentaje de micorrizas monopodiales (91%) en relación a los dicotómicos (8.5%) y coraloides (0.6%). Se determinaron relaciones positivas significativas entre las variables morfológicas, pero éstas sobre P. radiata presentaron asociaciones no significativas con el número de micorrizas. El uso individual y en mezcla de hongos ectomicorrízicos silvestres incrementó la calidad morfológica y biológica de P. radiata, por ello se recomienda la aplicación de estos hongos para la producción de plántulas en viveros de Vilcashuamán y otras zonas altoandinas.
... As the strain tested in this study was isolated from the roots of green alder (Alnus crispa (Aiton) Pursh; accepted name Alnus viridis ssp. crispa (Aiton) Turrill) (see Supplementary Table S1), 1 this might explain the absence of a beneficial effect of the P. fortinii inoculation treatment, as previously reported (Bruns et al. 2002;Lofgren et al. 2018). Future experiments should also aim to test if the effect of P. fortinii is "host dependent". ...
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Plants maintain beneficial mutualistic relationships with the mycobiont communities found in their rhizosphere, leading to an increase in plant productivity and health. In nutrient-depleted substrates like mine tailings, mycobiont inoculation is often recommended to help restore a successful plant cover. Our 15-week greenhouse experiment aimed to assess the individual effects of a dark septate endophyte (Phialocephala fortinii C.J.K. Wang & H.E. Wilcox #4 (KX611529)) and two Helotiales strains (Rhizoscyphus ericae (D.J. Read) W.Y. Zhuang & Korf #22 (EU221877) and Meliniomyces sp. #1 (KT275679)) on the growth of plane-leaved willow (Salix planifolia Pursh) cuttings on sterilized and unsterilized waste rock. Rhizoscyphus ericae increased shoot biomass of cuttings on sterilized waste rock, whereas Meliniomyces sp. had a positive effect on cuttings grown on unsterilized waste rock. However, P. fortinii strain had no effect on the survival rate, shoot production, and biomass production of S. planifolia cuttings. This study demonstrates that controlled inoculation with ecologically well-adapted mycobionts could promote plant establishment and productivity on abandoned waste rock and could be an efficient and integrated biotechnological approach for ecological restoration of Canadian mining boreal ecosystems.
... Restoration efforts often involve controlling invasive species (Weidlich et al. 2020), which may rely on mutualists (Vogelsang & Bever 2009;Moyano et al. 2020), but little is known about the consequences of having exotic soil microbiota in areas where exotic plants have been removed. For ECMs, interactions between native plants and exotic fungi do not necessarily cease after the removal of exotic plant species (Lofgren et al. 2018). ...
Article
As restoration ecology begins to engage more formally with the role of belowground interactions, we note that there is an even greater gap in knowledge of the role ectomycorrhizae (ECMs) have in ecological restoration in the neotropical region. Even though there are a few records of ECMs in the Neotropics not much is known about their function. Here we highlight This article is protected by copyright. All rights reserved. the underestimated importance of ECMs in neotropical coastal zones, discuss how we could use the vegetation on the coast of the Atlantic Forest, called restinga, as a model to investigate tropical ECMs, and explore further possibilities that can be used in restoration projects.
... Agricultural trials showed that Serendipita vermifera was unable to move 16 cm through the soil to colonize nearby species during an 8 week experiment (Ray et al., 2018). Given that OMF are thought to occupy niches along a continuum from soil saprotrophs to root endophytes (Selosse et al., 2018), and that there is growing evidence that some fungi associate with particular hosts (Lofgren et al., 2018;Martino et al., 2018), it will be important to design sampling procedures specific to orchid mycorrhizal fungi as they may also associate with particular hosts other than orchids. These procedures may need to include identifying the optimal season (as some fungi may be seasonally undetectable at low quantities in the soil) and the inclusion of host plant roots in the sampling design as is used for other root endophytes. ...
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Background and aims: In orchid conservation, quantifying the specificity of mycorrhizal associations, and establishing which orchid species use the same fungal taxa, is important for sourcing suitable fungi for symbiotic propagation and selecting sites for conservation translocation. For Caladenia subgenus Calonema (Orchidaceae), which contains 58 threatened species, we ask: (1) How many taxa of Serendipita mycorrhizal fungi do threatened species of Caladenia associate with? (2) Do threatened Caladenia share orchid mycorrhizal fungi with common Caladenia? (3) How geographically widespread are mycorrhizal fungi associated with Caladenia? Methods: Fungi were isolated from 127 Caladenia species followed by DNA sequencing of the ITS sequence locus. We used a 4.1- 6 % sequence divergence cut-off range to delimit Serendipita Operational Taxonomic Units (OTUs). We conducted trials testing the ability of fungal isolates to support germination and plant growth. A total of 597 Serendipita isolates from Caladenia, collected from across the Australian continent, were used to estimate the geographic range of OTUs. Results: Across the genus, Caladenia associated with 10 OTUs of Serendipita (Serendipitaceae) mycorrhizal fungi. Specificity was high, with 19 of the 23 threatened Caladenia species sampled in detail associating solely with OTU A, which supported plants from germination to adulthood. The majority of populations of Caladenia associated with one OTU per site. Fungal sharing was extensive, with 62 of the 79 Caladenia sampled in subgenus Calonema associating with OTU A. Most Serendipita OTUs were geographically widespread. Conclusions: Mycorrhizal fungi can be isolated from related common species to propagate threatened Caladenia. Because of high specificity of most Caladenia species, only small numbers of OTUs typically need to be considered for conservation translocation. When selecting translocation sites, the geographic range of the fungi is not a limiting factor, and using related Caladenia species to infer the presence of suitable fungal OTUs may be feasible.
... Similarly, ectomycorrhizal (ECM) fungi can display a broad host range (Marx and Krupa, 1978), although many have well recognized host specificity (Molina et al., 1992;Lofgren et al., 2018). Ectomycorrhizal fungi are associated with plant species along a host spectrum from broad to narrow (Molina et al., 1992). ...
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Black Locust (Robinia pseudoacacia L.) is a woody legume with a worldwide distribution. Its ecological and economical importance is largely due to fast growth and dinitrogen (N2)-fixation ability with rhizobia. These features make Black Locust suitable as a model species for other woody legumes as well. However, its symbiotic association with mycorrhizal fungi has not gained much attention. The small body of literature published indicates that this mycorrhizal association interacts with symbiotic N2-fixation, greatly enhancing the ecological and physiological performance of Black Locust by improving its rate of growth, nutrition status and resistance to stress conditions, such as drought and salt and heavy metal accumulation. Here we summarize the current knowledge on the benefits of the association of Black Locust with arbuscular mycorrhizal fungi with the aim of providing future research directions on how this symbiotic partnership is involved in a tripartite symbiotic association including rhizobia. This association is of particular importance considering both the invasive nature of Black Locust, its economic and cultural importance and its use in restoration of degraded or contaminated landscapes.
... Diversification associated with host shifting seen in younger clades, like R. peckii, may be driven by the inability of certain populations to track changing host distributions. Host switching could emerge as a legacy effect from relictual inoculum persisting in soil, allowing opportunistic contact with non-native hosts (Lofgren et al., 2018). ...
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Numerous lineages of mushroom-forming fungi have been subject to bursts of diversification throughout their evolutionary history, events that can impact our ability to infer well-resolved phylogenies. However, groups that have undergone quick genetic change may have the highest adaptive potential. As the second largest genus of mushroom-forming fungi, Russula provides an excellent model for studying hyper-diversification and processes in evolution that drives it. This study focuses on the morphologically defined group – Russula subsection Roseinae. Species hypotheses based on morphological differentiation and multi-locus phylogenetic analyses are tested in the Roseinae using different applications of the multi-species coalescent model. Based on this combined approach, we recognize fourteen species in Roseinae including the Albida and wholly novel Magnarosea clades. Reconstruction of biogeographic and host association history suggest that parapatric speciation in refugia during glacial cycles of the Pleistocene drove diversification within the Roseinae, which is found to have a Laurasian distribution with an evolutionary origin in the Appalachian Mountains of eastern North America. Finally, we detect jump dispersal at a continental scale that has driven diversification since the most recent glacial cycles.
... In agreement with these findings, we found the genus Russula to be the second most abundant genus associated with the four different hosts ( Figure S5). An example of host expansion triggered by past presence of other tree species in the stand, was shown for Suillus subaureus (Lofgren, Nguyen, & Kennedy, 2018). Nevertheless, in our study, we found Suillus granulatus and Suillus viscidus exclusively on roots of the two conifers, Pinus and Larix respectively (Figure 1a). ...
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The mutualistic symbiosis between forest trees and ectomycorrhizal fungi (EMF) is among the most ubiquitous and successful interactions in terrestrial ecosystems. Specific species of EMF are known to colonize specific tree species, benefitting from their carbon source, and in turn, improving their access to soil water and nutrients. EMF also form extensive mycelial networks that can link multiple root‐tips of different trees. Yet the number of tree species connected by such mycelial networks, and the traffic of material across them, are just now under study. Recently we reported substantial belowground carbon transfer between Picea, Pinus, Larix and Fagus trees in a mature forest. Here we analyze the EMF community of these same individual trees and identify the most likely taxa responsible for the observed carbon transfer. Among the nearly 1200 EMF root‐tips examined, 50‐70% belong to operational taxonomic units (OTUs) that were associated with 3 or 4 tree host species, and 90% of all OTUs were associated with at least two tree species. Sporocarp 13C signals indicated that carbon originating from labeled Picea trees was transferred among trees through EMF networks. Interestingly, phylogenetically more closely related tree species exhibited more similar EMF communities and exchanged more carbon. Our results show that belowground carbon transfer is well orchestrated by the evolution of EMFs and tree symbiosis.
... First, the middle gradient sites (si2 or si3) were either encountered with early-stage (Ulmus japonica, Syringa reticulata and Maackia amurensis) or late-stage (Ulmus laciniata and Tilia mandshurica) vegetation (Table 1). Second, ECM species composition and colonization can be significantly influenced by vegetation composition, especially in terms of host identity (Hewitt et al., 2017;Jonsson et al., 1999;Lofgren et al., 2018), and different life-strategy vegetation (such as early-successional vs. late-successional trees) may have different associated ECM fungal species (Taudiere et al., 2015). Therefore, as previously reported (Asplund et al., 2019;Toljander et al., 2006), mixed-forest stands (i.e., si2 and si3) encountered the highest number of ECM taxa. ...
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... Strict host specificity is rare in ECM fungi (Churchland & Grayston, 2014), and many ECM fungi can simultaneously colonise dozens of plants (Horton & van der Heijden, 2008). Interestingly, recent evidence also illustrated that ECM host specificity patterns depend on the mode of colonisation (Lofgren, Nguyen, & Kennedy, 2018), and that tree genetics influences the composition of ECM communities (Gehring, Sthultz, Flores-Rentería, Whipple, & Whitham, 2017). A low specificity can provide plants with a competitive advantage in the uptake of nutrients in comparison to non-host species, or plant species with a high specificity. ...
... Among fungi, many are specific to particular families or genera of plants (Molina and Horton 2015); among plants, although strict specificity to one or a few species of fungi is almost entirely restricted to mycoheterotrophs (Bruns et al. 2002), the suite of symbionts a plant supports often varies predictably with plant taxonomy (Molina and Horton 2015). In many cases, this specificity may be exerted at the spore germination stage: Host-specific fungi will not germinate until appropriate roots are present, despite being capable of broader associations as hyphae (Massicotte et al. 1994;Lofgren et al. 2018). Additionally, recent research into ectomycorrhizal fungal gene expression has identified many small secreted peptides that appear to be expressed at the initiation of symbiosis, and whose identities can vary considerably among fungal taxa (Plett et al. 2011;Liao et al. 2016). ...
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Although ectomycorrhizal fungi have well-recognized effects on ecological processes ranging from plant community dynamics to carbon cycling rates, it is unclear if plants are able to actively influence the structure of these fungal communities. To address this knowledge gap, we performed two complementary experiments to determine (1) whether ectomycorrhizal plants can discriminate among potential fungal partners, and (2) to what extent the plants might reward better mutualists. In experiment 1, split-root Larix occidentalis seedlings were inoculated with spores from three Suillus species (S. clintonianus, S. grisellus, and S. spectabilis). In experiment 2, we manipulated the symbiotic quality of Suillus brevipes isolates on split-root Pinus muricata seedlings by changing the nitrogen resources available, and used carbon-13 labeling to track host investment in fungi. In experiment 1, we found that hosts can discriminate in multi-species settings. The split-root seedlings inhibited colonization by S. spectabilis whenever another fungus was available, despite similar benefits from all three fungi. In experiment 2, we found that roots and fungi with greater nitrogen supplies received more plant carbon. Our results suggest that plants may be able to regulate this symbiosis at a relatively fine scale, and that this regulation can be integrated across spatially separated portions of a root system.
... Strict host specificity is rare in ECM fungi (Churchland & Grayston, 2014), and many ECM fungi can simultaneously colonise dozens of plants (Horton & van der Heijden, 2008). Interestingly, recent evidence also illustrated that ECM host specificity patterns depend on the mode of colonisation (Lofgren, Nguyen, & Kennedy, 2018), and that tree genetics influences the composition of ECM communities (Gehring, Sthultz, Flores-Rentería, Whipple, & Whitham, 2017). A low specificity can provide plants with a competitive advantage in the uptake of nutrients in comparison to non-host species, or plant species with a high specificity. ...
Chapter
Trees can be associated with dozens of fungi helping them to acquire resources from forest soils. The most widespread mutualistic association in boreal and temperate forests is the ectomycorrhizal symbiosis. This symbiosis involves mushroom-forming fungi of basidiomycota, ascomycota, and some zygomycota clades and the roots of woody plant species, including oaks, poplars or pines. Although the impact of this association on ecosystem production and tree nutrition is investigated for about a century, our understanding on the molecular mechanisms that control water and nutrient fluxes between plant and fungal partners is still limited. Here, we review the recent knowledge on the ectomycorrhizal contribution to tree nutrition. We specifically highlight the molecular mechanisms driving the acquisition, translocation and release of water and nutrients in ectomycorrhizal systems. We particularly focus on the transport of macronutrients, including nitrogen, phosphorus, potassium, sulphur and calcium, micronutrients, and water by the symbiotic partner. We also provide background on the evolution, diversity, and importance of this symbiosis, identify knowledge gaps, and propose future research directions.
... There is still a need to strengthen the 'mycocentric perspective' (Fitter et al., 2000), because specificity in fungal-plant interactions (e.g. Lofgren et al., 2018; in this issue of New Phytologist, pp. 1273-1284) work both ways. ...
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Ectomycorrhizal (EM) effects on forest ecosystem carbon (C) and nitrogen (N) cycling are highly variable, which may be due to underappreciated functional differences among EM-associating trees. We hypothesize that differences in functional traits among EM tree genera will correspond to differences in soil organic matter (SOM) dynamics. We explored how differences among three genera of angiosperm EM trees ( Quercus, Carya, and Tilia ) in functional traits associated with leaf litter quality, resource use and allocation patterns, and microbiome assembly related to overall soil biogeochemical properties. In support of our hypothesis, we found consistent differences among EM tree genera in function traits. Quercus trees had lower litter quality, lower δ ¹³ C in SOM, higher δ ¹⁵ N in leaf tissues, greater oxidative extracellular enzyme activities, and higher EM fungal diversity than Tilia trees, while Carya trees were often intermediary. These functional traits corresponded to overall SOM C and N dynamics and soil fungal and bacterial community composition. Our findings suggest that trait variation among EM-associating tree species should be an important consideration in assessing plant-soil relationships such that EM trees cannot be categorized as a unified functional guild.
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Ectomycorrhizas are ubiquitous symbiotic associations between host trees and soil fungi. While the seasonal changes of the taxonomic community structure of ectomycorrhizal fungi have been studied extensively, the temporal dynamics of ectomycorrhizal exploration types which have been proposed for elucidating the functional roles of ectomycorrhizas have not been fully examined. The purpose of the study is to test the hypothesis of whether the abundance of the exploration types in the hosts with different phenology shows different temporal patterns over the seasons. Two host species, deciduous Quercus acutissima and evergreen Q. glauca, were planted in growth containers with natural forest soils and were grown in single or combined species treatment, under similar environmental conditions and in shared soil spore banks of the ectomycorrhizal fungi. The ectomycorrhizal exploration types that occurred on these two host species in two different treatments were observed for two growing seasons. The observed exploration types, namely contact, short-distance, and long-distance type as well as the overall abundance of the ectomycorrhizas showed distinct temporal patterns although no specific response to the host seasonal phenology was found. The abundances of the contact type showed no relation to the seasons whereas those of the short- and the long-distance type increased with time. The formation of the long-distance type was strongly influenced by the host species treatments while that of the other two types was not so. Therefore, the different exploration types demonstrate distinct temporal patterns depending on the types but no specific seasonal responses.
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Research on mycorrhizal symbiosis has been slowed by a lack of established study systems. To address this challenge, we have been developing Suillus, a widespread ecologically and economically relevant fungal genus primarily associated with the plant family Pinaceae, into a model system for studying ectomycorrhizal (ECM) associations. Over the last decade, we have compiled extensive genomic resources, culture libraries, a phenotype database, and protocols for manipulating Suillus fungi with and without their tree partners. Our efforts have already resulted in a large number of publicly available genomes, transcriptomes, and respective annotations, as well as advances in our understanding of mycorrhizal partner specificity and host communication, fungal and plant nutrition, environmental adaptation, soil nutrient cycling, interspecific competition, and biological invasions. Here, we highlight the most significant recent findings enabled by Suillus, present a suite of protocols for working with the genus, and discuss how Suillus is emerging as an important model to elucidate the ecology and evolution of ECM interactions.
Chapter
Anthropogenic and natural activities-based ecosystem disturbances lead to leftover degraded barren lands. Ectomycorrhizal (ECM) fungi play an important role in regulating the nutrient balance of the terrestrial ecosystem, assisting plant regeneration on disturbed lands by conferring improved tolerance against various biotic and abiotic stresses. There are several challenges and knowledge gaps in utilizing the ECM fungi for large-scale ecosystem restoration programs. For strengthening the successful utilization of ECM fungal applications in out-fields, this chapter has summarized the various applications, mechanisms, and considerable important parameters of ECM symbiosis in regenerating and improving host plant growth against diverse stress conditions such as drought stress, heavy metal stress, and forest fire, thus leading to the rehabilitation of degraded lands. Above all, the major challenge remains the production of large-scale ECM fungal inocula for restoration programs. This chapter has summarized the various ECM inoculation techniques, including their merits and demerits. This chapter also highlights the essential role of ECM fungi in nutrient dynamics of host plants with soil and ECM fungal application as biofertilizers in agriculture and commercial nurseries, thereby replacing harmful chemical fertilizers.KeywordsEctomycorrhizal fungiHost plantsRehabilitation programsStress toleranceNutrient cycling
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Mushrooms have a long history of cultivation, dating back to 600 AD. However, most edible mushroom species worldwide are still gathered from the wild, a practice which is unsustainable in contributing to global food security. Cultivation of saprotrophic mushroom species has successfully used agricultural waste as growing substrate. Their mycorrhizal counterparts, however, remain dependent on their woody hosts and seasonality thereby being less accessible to urban communities. The main reason has been the lack of methods which effectively simulate mycorrhizal symbiotic environments. Apart from requiring particular species of bacteria for mycorrhization with their woody host species, mycorrhizal mushrooms also strictly require glucose or fructose as their only source of carbon. Hence, sustainable off-host cultivation of mycorrhizal mushrooms will require better understanding of exact conditions of mycorrhization and fructification. In this review, a brief history of use and general biology of mushrooms, and the cultivation methods employed for non-mycorrhizal and mycorrhizal mushrooms are discussed. Finally, a discussion is provided on the prospects for Sub-Saharan Africa in developing modern sustainable cultivation methods for wild mushrooms towards meeting the key UN Sustainable Development Goals.
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Background Most species of the Russulaceae are ectomycorrhizal (ECM) fungi, which are widely distributed in different types of forest ecology and drive important ecological and economic functions. Little is known about the composition variation of the Russulaceae fungal community aboveground and in the root and soil during the growing season (June–October) from a Quercus mongolica forest. In this study, we investigated the changes in the composition of the Russulaceae during the growing season of this type of forest in Wudalianchi City, China. Methods To achieve this, the Sanger sequencing method was used to identify the Russulaceae aboveground, and the high-throughput sequencing method was used to analyze the species composition of the Russulaceae in the root and soil. Moreover, we used the Pearson correlation analysis, the redundancy analysis and the multivariate linear regression analysis to analyze which factors significantly affected the composition and distribution of the Russulaceae fungal community. Results A total of 56 species of Russulaceae were detected in the Q. mongolica forest, which included 48 species of Russula , seven species of Lactarius , and one species of Lactifluus . Russula was the dominant group. During the growing season, the sporocarps of Russula appeared earlier than those of Lactarius . The number of species aboveground exhibited a decrease after the increase and were significantly affected by the average monthly air temperature ( r = −0.822, p = 0.045), average monthly relative humidity ( r = −0.826, p = 0.043), monthly rainfall ( r = 0.850, p = 0.032), soil moisture ( r = 0.841, p = 0.036) and soil organic matter ( r = 0.911, p = 0.012). In the roots and soils under the Q. mongolica forest, the number of species did not show an apparent trend. The number of species from the roots was the largest in September and the lowest in August, while those from the soils were the largest in October and the lowest in June. Both were significantly affected by the average monthly air temperature ( r ² = 0.6083, p = 0.040) and monthly rainfall ( r ² = 0.6354, p = 0.039). Moreover, the relative abundance of Russula and Lactarius in the roots and soils showed a linear correlation with the relative abundance of the other fungal genera.
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The genus Suillus represents one of the most recognizable groups of mushrooms in conifer forests throughout the Northern Hemisphere. Although for decades the genus has been relatively well defined morphologically, previous molecular phylogenetic assessments have provided important yet preliminary insights into its evolutionary history. Here we present the first large-scale phylogenetic study of the boundaries of each species in the genus Suillus based on the most current internal transcribed spacer (ITS) barcode sequences available in public databases, as well as sequencing of 224 vouchered specimens and cultures, 15 of which were type specimens from North America. We found that species boundaries delimited by morphological data are broadly congruent with those based on ITS sequences. However, some species appear to have been described several times under different names, several species groups cannot be resolved by ITS sequences alone, and undescribed taxa are apparent, especially in Asia. Therefore, we elevated S. tomentosus var. discolor to S. discolor; proposed synonymies of S. neoalbidipes with S. glandulosipes, S. borealis with S. brunnescens, Boletus serotinus, B. solidipes with Suillus elbensis, S. lactifluus with S. granulatus, S. himalayensis with S. americanus; and proposed usage of the names S. clintonianus in the place of the North American S. grevillei, S. weaverae for North American S. granulatus, S. ampliporus in the place of the North American S. cavipes, and S. elbensis in place of the North American S. viscidus We showed that the majority of Suillus species have strong affinities for particular host genera. Although deep node support was low, geographic differentiation was apparent, with species from North America, Eurasia, and Asia often forming their own clades. Collectively, this comprehensive genus-level phylogenetic integration of currently available Suillus ITS molecular data and metadata will aid future taxonomic and ecological work on an important group of ectomycorrhizal fungi.
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The roots of most plants are colonized by symbiotic fungi to form mycorrhiza, which play a critical role in the capture of nutrients from the soil and therefore in plant nutrition. Mycorrhizal Symbiosis is recognized as the definitive work in this area. Since the last edition was published there have been major advances in the field, particularly in the area of molecular biology, and the new edition has been fully revised and updated to incorporate these exciting new developments. . Over 50% new material . Includes expanded color plate section . Covers all aspects of mycorrhiza . Presents new taxonomy . Discusses the impact of proteomics and genomics on research in this area.
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