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Decreasing returns in resource acquisition ability with increasing leaf mass investment is called ‘diminishing returns’, which provides important insights into plant economy. Yet, whether this is true for fine roots and how root resource acquisition strategies change with forest succession remain unclear. We investigated the scaling relationship between fine‐root length (L) and mass (M) for 215 topsoil cores from 24 plots across four successional stages in tropical forests of Xishuangbanna, southwestern China. We also assessed the relative effects of edaphic conditions, leaf functional traits, tree species diversity and soil fungal factors on L versus M scaling relationship using hierarchical variation partitioning. Our results revealed the existence of diminishing returns in root length (L vs. M scaling exponent <1), and that the exponent was higher in late‐ than early‐successional forests, corresponding to a strategy shifting from ‘do‐it‐yourself’ in the late‐successional stage to ‘outsourcing’ resource uptake by soil fungi in the early‐successional stage. Soil fungal abundance was the main driver of changes in the L versus M scaling exponent across plots (explained 58% of variances), with root endophytic fungi the strongest predictor (22.11%), followed by mycorrhizal fungi (10.41%), while other factors (leaf functional traits, edaphic nutrient conditions and tree species diversity) exerted weak effects. Our results suggest that root endophytic and mycorrhizal fungi act as key modulators of root economy changes during forest succession, but the former has received less attention previously. L versus M scaling exponent may be a better indicator for shifts in root resource acquisition strategy than the commonly used specific root length. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Terrestrial plants form primarily mutualistic symbiosis with mycorrhizal fungi based on a compatible exchange of solutes between plant and fungal partners. A key attribute of this symbiosis is the acquisition of soil nutrients by the fungus for the benefit of the plant in exchange for a carbon supply to the fungus. The interaction can range from mutualistic to parasitic depending on environmental and physiological contexts. This review considers current knowledge of the functionality of ectomycorrhizal (EM) symbiosis in the mobilisation and acquisition of soil nitrogen (N) in northern hemisphere forest ecosystems, highlighting the functional diversity of the fungi and the variation of symbiotic benefits, including the dynamics of N transfer to the plant. It provides an overview of recent advances in understanding 'mycorrhizal decomposition' for N release from organic or mineral-organic forms. Additionally, it emphasises the taxon-specific traits of EM fungi in soil N uptake. While the effects of EM communities on tree N are likely consistent across different communities regardless of species composition, the sink activities of various fungal taxa for tree carbon and N resources drive the dynamic continuum of mutualistic interactions. We posit that ectomycorrhizas contribute in a species-specific but complementary manner to benefit tree N nutrition. Therefore, alterations in diversity may impact fungal-plant resource exchange and, ultimately, the role of ectomycorrhizas in tree N nutrition. Understanding the dynamics of EM functions along the mutualism-parasitism continuum in forest ecosystems is essential for the effective management of ecosystem restoration and resilience amidst climate change. Key points: • Mycorrhizal symbiosis spans a continuum from invested to appropriated benefits. • Ectomycorrhizal fungal communities exhibit a high functional diversity. • Tree nitrogen nutrition benefits from the diversity of ectomycorrhizal fungi. [ABSTRACT FROM AUTHOR]

In nature, microbes do not thrive in seclusion but are involved in complex interactions within- and between-microbial kingdoms. Among these, symbiotic associations with mycorrhizal fungi and nitrogen-fixing bacteria are namely known to improve plant health, while providing resources to benefit other microbial members. Yet, it is not clear how these microbial symbionts interact with each other or how they impact the microbiota network architecture. We used an extensive co-occurrence network analysis, including rhizosphere and roots samples from six plant species in a natural desert in AlUla region (Kingdom of Saudi Arabia) and described how these symbionts were structured within the plant microbiota network. We found that the plant species was a significant driver of its microbiota composition and also of the specificity of its interactions in networks at the microbial taxa level. Despite this specificity, a motif was conserved across all networks, i.e., mycorrhizal fungi highly covaried with other mycorrhizal fungi, especially in plant roots—this pattern is known as assortativity. This structural property might reflect their ecological niche preference or their ability to opportunistically colonize roots of plant species considered non symbiotic e.g., H. salicornicum, an Amaranthaceae. Furthermore, these results are consistent with previous findings regarding the architecture of the gut microbiome network, where a high level of assortativity at the level of bacterial and fungal orders was also identified, suggesting the existence of general rules of microbiome assembly. Otherwise, the bacterial symbionts Rhizobiales and Frankiales covaried with other bacterial and fungal members, and were highly structural to the intra- and inter-kingdom networks. Our extensive co-occurrence network analysis of plant microbiota and study of symbiont assortativity, provided further evidence on the importance of bacterial and fungal symbionts in structuring the global plant microbiota network. [ABSTRACT FROM AUTHOR]

Despite gaining significant attention in recent years, it remains unclear whether mycorrhizal fungi distribute meaningful amounts of resources among trees in ways that increase the fitness of the receiving trees. To investigate this, we used pairs of shaded and unshaded Pinus halepensis or Quercus calliprinos saplings, growing in both inter‐ and intra‐specific combinations outdoors in forest soil. We examined the combined effects of indirect and direct below‐ground connections on tree performance and Non‐Structural Carbohydrate (NSC) pools. Although we did not observe any growth benefits, shaded recipient oaks exhibited higher levels of root and branch NSC compared to their control counterparts, which were not connected below‐ground. This finding suggests a potential benefit of establishing below‐ground connections. However, no such benefits were observed among the unshaded pairs or in the other inter‐ and intra‐specific pairs of pines and oaks. We monitored the carbon (C) flow from a 13CO2‐labelled donor pine tree to a below‐ground connected oak tree and demonstrated C transfer from pines to shaded oaks. We also identified the main fungal symbionts interacting with pines and oaks. Our findings indicate that the effects of below‐ground C transfer are context‐dependent, manifesting in nuanced alterations in plant NSC that are not readily apparent through conventional growth metrics. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Mycorrhizal fungi, a category of fungi that form symbiotic relationships with plant roots, can participate in the induction of plant disease resistance by secreting phosphatase enzymes. While extensive research exists on the mechanisms by which mycorrhizal fungi induce resistance, the specific contributions of phosphatases to these processes require further elucidation. This article reviews the spectrum of mycorrhizal fungi-induced resistance mechanisms and synthesizes a current understanding of how phosphatases mediate these effects, such as the induction of defense structures in plants, the negative regulation of plant immune responses, and the limitation of pathogen invasion and spread. It explores the role of phosphatases in the resistance induced by mycorrhizal fungi and provides prospective future research directions in this field. [ABSTRACT FROM AUTHOR]

Symbiotic nitrogen (N) fixation has the potential to replenish fire‐induced N losses in frequently burned ecosystems. A strong relationship between fire and fixation may exist because fire volatilizes N and mineralizes phosphorus (P), creating N‐poor, P‐rich soils that favour plants capable of N‐fixation. However, human activities have enriched ecosystems with N, which may complicate the interplay among fire, fixation and soil P.We evaluated how N and P modulate the relationship between fire and symbiotic N fixation in longleaf pine savannas, where it was previously documented that N fixation fails to replenish N losses from fire. Across gradients of stand age and fire frequency, we investigated how N and P availability influence fixation, and we established a nutrient addition experiment to evaluate the effects of N and P on legume growth, fixation and mycorrhizal investment.We uncovered a clear signal of P limitation of herbaceous legumes. Legume growth and fixation were linked to the availability of soil mineral P and were further stimulated by P additions. In contrast, neither soil N availability nor N additions affected legume growth or fixation.Synthesis. Our findings suggest that symbiotic N fixation in sandhill longleaf pine savannas is controlled by soil P availability, which varies according to soil age and parent material. Therefore, fixation may only counterbalance N losses from fire if there is enough P in the soil to support this process. Nonetheless, recent N enrichment in contemporary longleaf pine ecosystems may have reduced the importance of N fixation as a post‐fire recovery mechanism. [ABSTRACT FROM AUTHOR]

The survival and productivity of potato plantlets transplanted from in vitro to commercial hydroponic minituber culture are crucial. Mycorrhizal fungi are an efficient tool to enhance potato nutrient uptake, survival, and productivity under these conditions. This study aimed to assess the effect of mycorrhizal fungi on improving the yield of minitubers and nutrient uptake in potatoes transferred from the in vitro environment to the greenhouse. This study was conducted in a greenhouse in Hamadan province, I.R. Iran, in 2013. The experimental design was factorial, including treatments with and without inoculation with the mycorrhizal fungus Rhizophagus irregularis and varying phosphorus (P) concentrations in Hoagland's solution (100%, 75%, 50%, and 25% of its maximum content, i.e. 0.965, 0.482, 0.241, and 0.12 mM H2PO4-) with three replications on potato plantlets transferred from in vitro to pots. The results indicated that the highest colonization percentage was achieved with 25% P and inoculation. The highest number of minitubers (8.9), total minituber weight per plant (53.2 grams), plant height (54.6 cm), minituber (0.38%) and leaf (0.363%) P content, minituber (33 mg/kg) and leaf (65 mg/kg) manganese (Mn) content, and minituber (38 mg/kg) and leaf (65 mg/kg) zinc (Zn) content were obtained with inoculation and 75% P of Hoagland nutrient solution, which was statistically comparable to the inoculation with 100% P treatment. In summary, inoculating potato plantlets with mycorrhiza can enhance minituber yield and nutrient uptake and potentially replace approximately 50% of the P requirement in hydroponic solutions. [ABSTRACT FROM AUTHOR]

Background and Aims The earliest-diverging orchid lineage, Apostasioideae, consists only of two genera: Apostasia and Neuwiedia. Previous reports of Apostasia nipponica indicated a symbiotic association with an ectomycorrhiza-forming Ceratobasidiaceae clade and partial utilization of fungal carbon during the adult stage. However, the trophic strategy of Neuwiedia throughout its development remains unidentified. To further improve our understanding of mycoheterotrophy in the Apostasioideae, this study focused on Neuwiedia malipoensis examining both the mycorrhizal association and the physiological ecology of this orchid species across various development stages. Methods We identified the major mycorrhizal fungi of N. malipoensis protocorm, leafy seedling and adult stages using molecular barcoding. To reveal nutritional resources utilized by N. malipoensis , we compared stable isotope natural abundances (δ 13C, δ 15N, δ 2H, δ 18O) of different developmental stages with those of autotrophic reference plants. Key Results Protocorms exhibited an association with saprotrophic Ceratobasidiaceae rather than ectomycorrhiza-forming Ceratobasidiaceae and the 13C signature was characteristic of their fully mycoheterotrophic nutrition. Seedlings and adults were predominantly associated with saprotrophic fungi belonging to the Tulasnellaceae. While 13C and 2H stable isotope data revealed partial mycoheterotrophy of seedlings, it is unclear to what extent the fungal carbon supply is reduced in adult N. malipoensis. However, the 15N enrichment of mature N. malipoensis suggests partially mycoheterotrophic nutrition. Our data indicated a transition in mycorrhizal partners during ontogenetic development with decreasing dependency of N. malipoensis on fungal nitrogen and carbon. Conclusions The divergence in mycorrhizal partners between N. malipoensis and A. nipponica indicates different resource acquisition strategies and allows various habitat options in the earliest-diverging orchid lineage, Apostasioideae. While A. nipponica relies on the heterotrophic carbon gain from its ectomycorrhizal fungal partner and thus on forest habitats, N. malipoensis rather relies on own photosynthetic carbon gain as an adult, allowing it to establish in habitats as widely distributed as those where Rhizoctonia fungi occur. [ABSTRACT FROM AUTHOR]

Plants and mycorrhizal fungi form mutualistic relationships that affect how resources flow between organisms and within ecosystems. Common mycorrhizal networks (CMNs) could facilitate preferential transfer of carbon and limiting nutrients, but this remains difficult to predict. Do CMNs favour fungal resource acquisition at the expense of plant resource demands (a fungi‐centric view), or are they passive channels through which plants regulate resource fluxes (a plant‐centric view)? We used stable isotope tracers (13CO2 and 15NH3), plant traits, and mycorrhizal DNA to quantify above‐ and below‐ground carbon and nitrogen transfer between 18 plant species along a 520‐km latitudinal gradient in the Pacific Northwest, USA. Plant functional type and tissue stoichiometry were the most important predictors of interspecific resource transfer. Of ‘donor’ plants, 98% were 13C‐enriched, but we detected transfer in only 2% of ‘receiver’ plants. However, all donors were 15N‐enriched and we detected transfer in 81% of receivers. Nitrogen was preferentially transferred to annuals (0.26 ± 0.50 mg N per g leaf mass) compared with perennials (0.13 ± 0.30 mg N per g leaf mass). This corresponded with tissue stoichiometry differences. Synthesis Our findings suggest that plants and fungi that are located closer together in space and with stronger demand for resources over time are more likely to receive larger amounts of those limiting resources. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Introduction: Scleroderma bovista can form symbiotic ectomycorrhizal fungi with hazel roots. The mechanism through which S. bovista promotes hazelnut growth remains unclear. Methods: This study aimed to evaluate the effect of ectomycorrhizal fungus S. bovista on the growth and development of hazel roots and gene expression changes through comparative transcriptome analysis. Results: After inoculation with S. bovista, the fungus symbiotically formed ectomycorrhiza with hazel roots. The fresh weights of the aboveground and underground parts of My treatment (inoculated with S. bovista and formed mycorrhiza) were much higher than those of the control, respectively. The length, project area, surface area, volume, forks, and diameter of the inoculated seedlings root were 1.13 to 2.48 times higher than those of the control. In the paired comparison, 3,265 upregulated and 1,916 downregulated genes were identified. The most significantly enriched Gene Ontology term for the upregulated Differentially Expressed Genes was GO:0005215 (transporter activity). Immunohistochemical analysis suggested that the expression levels of auxin and Auxin Response Factor9 were significantly increased by S. bovista after the formation of mycorrhizal fungi in hazelnut root tips. Discussion: These results indicate that genes related to auxin biosynthesis, transport and signaling, and transport of nutrients may contribute to root development regulation in hazel ectomycorrhiza. [ABSTRACT FROM AUTHOR]

Orchids and arbuscular mycorrhiza (AM) plants evolved independently and have different structures and fungal partners, but they both facilitate nutrient uptake. Orchid mycorrhiza (OM) supports orchid seed germination, but unlike AM, its role in disease resistance of mature plants is largely unknown. Here, we examined whether OM induces systemic disease resistance against a necrotrophic pathogen in a similar fashion to AM. We investigated the priming effect of mycorrhizal fungi inoculation on resistance of a terrestrial orchid, Bletilla striata, to soft rot caused by Dickeya fangzhongdai. We found that root colonization by a compatible OM fungus primed B. striata seedlings and induced systemic resistance against the infection. Transcriptome analysis showed that priming was mediated by the downregulation of jasmonate and ethylene pathways and that these pathways are upregulated once infection occurs. Comparison with the reported transcriptome of AM fungus-colonized rice leaves revealed similar mechanisms in B. striata and in rice. These findings highlight a novel aspect of commonality between OM and AM plants in terms of induced systemic resistance. [ABSTRACT FROM AUTHOR]

Generally, orchids highly depend on specific fungi for seed germination and subsequent seedling development in nature. For medicinal orchids, obtaining compatible fungi is prerequisite for imitation of wild cultivation and conservation. In this study, the two important traditional Chinese medicinal orchids, Pleione bulbocodioides and Bletilla striata, were studied to screen out effective fungi for seed germination and seedling development. P. bulbocodioides seeds germinated and formed protocorms in all fungal and control treatments, but seedlings only developed in fungal Serendipita officinale (SO) and S. indica (SI) treatments and nutrient-rich medium MS treatment. At 90 days after incubation, the percentages of seedlings were 34.83 ± 3.4% and 27.59 ± 3.5% in SO and SI treatments, which were significantly higher than the MS treatment (18.39 ± 2.0%; all P < 0.05). At this stage, most seedlings in SO and SI treatments bore two leaves (Stage 5), and pelotons inside the basal cells of seedlings were clearly observed. For B. striata, seeds germinated up to seedlings with or without fungus, but seedlings developed rapidly in SI treatment. At 90 days after incubation, the percentage of seedlings in SI treatment reached 77.90 ± 4.1%, but was significantly lower than the nutrient-poor medium OMA treatment (85.18 ± 3.7%; P < 0.01), however, the seedlings in SI treatment were stronger than the seedlings in OMA treatment. The results suggested that P. bulbocodioides rely on compatible fungi for seeds germinated up to seedlings, and fungus SO could effectively promote seed germination and support seedling development; while B. striata can germinate up to seedling without any fungus, but compatible fungus S. indica can greatly speed up seed germination and promote seedling development. We suggest that S. officinale and S. indica fungi can be used in conservation practices or imitation of wild cultivation of these two important medicinal orchids, respectively. [ABSTRACT FROM AUTHOR]

The presented study determined the effect of biofertilizers on the growth and production of broad bean (Vicia faba L.) cultivars conducted during the autumn season of 2020–2021 at the Al-Mahaweel area, Babylon Governorate, Iraq. The experiment followed a randomized complete block design with two factors and three replicates. The first factor was the three broad bean cultivars—local, Turkish, and Spanish—while the second was four biofertilizer levels(control, Bacillus mucilaginous, and mycorrhizal fungi). The results showed the Spanish cultivar significantly excelled over other cultivars in yield-related traits, pods per plant (16.82), seeds per pod (6.11), seed yield (5,884.29 kg ha-1 ), and biological yield (12,599.05 kg ha-1 ). The mycorrhizal fungi biofertilizer treatment remarkably excelled for all treatments, i.e., pods per plant (17.84), seeds per pod (6.98), seed yield (5,874.11 kg ha-1 ), and biological yield (14,495.79 kg ha-1 ). Meanwhile, the interaction treatment (Spanish cultivar + mycorrhiza fungi) superbly shone and gave the highest rate for most studied traits. [ABSTRACT FROM AUTHOR]

Anaerobically mineralized nitrogen (AN) is a suitable soil health indicator. The AN is sensitive to soil use changes and is related to soil and particulate organic carbon and aggregate stability. This work aims to evaluate the relationship between AN and 1) easily extractable glomalin-related soil proteins; 2) abundance of arbuscular mycorrhizal fungi measured by the number of arbuscular mycorrhizal fungi spores, and 3) arbuscular mycorrhizal fungi activity (root colonization). Soil samples were taken at depths of 0-5 and 5-20 cm from cultivated and uncultivated plots throughout the southeastern province of Buenos Aires. Anaerobically mineralized nitrogen, soil organic carbon, particulate organic carbon, aggregate stability, easily extracted glomalin-related soil proteins and the logarithm of the number of arbuscular mycorrhizal fungi spores (log spores) at 0-5, 5-20 and 0-20 cm depths were determined. In wheat roots, the percentages of total infection and arbuscules at 0-20 cm were measured. At all depths, AN was positively correlated to easily extractable glomalin-related soil proteins (r=0.34-0.65), which is an indicator of arbuscular mycorrhizal fungi activity and abundance. Likewise, AN was positively related to log-spores (r=0.58-0.78), which is an indicator of arbuscular mycorrhizal fungi abundance. However, AN was not related to root colonization (the percentages of total infection and arbuscules) that manifests the activity of arbuscular mycorrhizal fungi at a specific moment. Thus, anaerobically mineralized nitrogen would be an indicator of mid- to long-term changes in arbuscular mycorrhizal fungi abundance and activity (easily extractable glomalin-related soil proteins and log-spores) resulting from soil use. Consequently, the AN would allow monitoring an important aspect of soil microbiological health associated with arbuscular mycorrhizal fungi. However, it is necessary to evaluate the relationships studied in this work in a wider range of soil situations. [ABSTRACT FROM AUTHOR]

Summary: Climate warming is severely affecting high‐latitude regions. In the Arctic tundra, it may lead to enhanced soil nutrient availability and interact with simultaneous changes in grazing pressure. It is presently unknown how these concurrently occurring global change drivers affect the root‐associated fungal communities, particularly mycorrhizal fungi, and whether changes coincide with shifts in plant mycorrhizal types.We investigated changes in root‐associated fungal communities and mycorrhizal types of the plant community in a 10‐yr factorial experiment with warming, fertilisation and grazing exclusion in a Finnish tundra grassland.The strongest determinant of the root‐associated fungal community was fertilisation, which consistently increased potential plant pathogen abundance and had contrasting effects on the different mycorrhizal fungal types, contingent on other treatments. Plant mycorrhizal types went through pronounced shifts, with warming favouring ecto‐ and ericoid mycorrhiza but not under fertilisation and grazing exclusion. Combination of all treatments resulted in dominance by arbuscular mycorrhizal plants. However, shifts in plant mycorrhizal types vs fungi were mostly but not always aligned in their magnitude and direction.Our results show that our ability to predict shifts in symbiotic and antagonistic fungal communities depend on simultaneous consideration of multiple global change factors that jointly alter plant and fungal communities. [ABSTRACT FROM AUTHOR]

To delve into the growth and physiological adaptations exhibited by the economically vital black wolfberry (Lycium ruthenicum) upon inoculation with arbuscular mycorrhizal fungi (AMF) under varying levels of saline–alkaline stress A series of pot experiments were conducted in a gradient saline–alkaline environment (0, 200, 400 mM NaCl: NaHCO3 = 1:1). One-year-old cuttings of black wolfberry, inoculated with two AMF species—Funneliformis mosseae (Fm) and Rhizophagus intraradices (Ri)—served as the experimental material, enabling a comprehensive analysis of seedling biomass, chlorophyll content, antioxidant enzyme activities, and other crucial physiological parameters. This study demonstrated that both Fm and Ri could form a symbiotic relationship with the root of Lycium ruthenicum. Notably, Fm inoculation significantly bolstered the growth of the underground parts, while exhibiting a remarkable capacity to scavenge reactive oxygen species (ROS), thereby effectively mitigating membrane oxidative damage induced by stress. Additionally, Fm promoted the accumulation of abscisic acid (ABA) in both leaves and roots, facilitating the exclusion of excess sodium ions from cells. Ri Inoculation primarily contributed to an enhancement in the chlorophyll b (Chlb) content, vital for sustaining photosynthesis processes. Furthermore, Ri's ability to enhance phosphorus (P) absorption under stressful conditions ensured a steady influx of essential nutrients. These findings point to different strategies employed for Fm and Ri inoculation. To holistically assess the saline–alkaline tolerance of each treatment group, a membership function analysis was employed, ultimately ranking the salt tolerance as Fm > Ri > non-mycorrhizal (NM) control. This finding holds paramount importance for the screening of highly resilient Lycium ruthenicum strains and offers invaluable theoretical underpinnings and technical guidance for the remediation of saline–alkaline soils, fostering sustainable agricultural practices in challenging environments. [ABSTRACT FROM AUTHOR]

Tree‐mycorrhizal associations are associated with patterns in nitrogen (N) availability and soil organic matter storage; however, we still lack a mechanistic understanding of what tree and fungal traits drive these patterns and how they will respond to global changes in soil N availability. To address this knowledge gap, we investigated how arbuscular mycorrhizal (AM)‐ and ectomycorrhizal (EcM)‐associated seedlings alter rhizodeposition in response to increased seedling inorganic N acquisition. We grew four species each of EcM and AM seedlings from forests of the eastern United States in a continuously 13C‐labeled atmosphere within an environmentally controlled chamber and subjected to three levels of 15N‐labeled fertilizer. We traced seedling 15N uptake from, and 13C‐labeled inputs (net rhizodeposition) into, root‐excluded or ‐included soil over a 5‐month growing season. N uptake by seedlings was positively related to rhizodeposition for EcM‐ but not AM‐associated seedlings in root‐included soils. Despite this contrast in rhizodeposition, there was no difference in soil C storage between mycorrhizal types over the course of the experiment. Instead root‐inclusive soils lost C, while root‐exclusive soils gained C. Our findings suggest that mycorrhizal associations mediate tree belowground C investment in response to inorganic N availability, but these differences do not affect C storage. Continued soil warming and N deposition under global change will increase soil inorganic N availability and our seedling results indicate this could lead to greater belowground C investment by EcM‐associated trees. This potential for less efficient N uptake by EcM‐trees could contribute to AM‐tree success and a shift toward more AM‐dominated temperate forests. [ABSTRACT FROM AUTHOR]

Purpose: Arbuscular mycorrhizal fungi (AMF) perform an ancestral and essential association with plant roots, where plants provide carbohydrates and lipids, and the fungi respond by translocating water and nutrients to the roots through the hyphae. There is a need to investigate the microbial community associated with the rhizosphere of mycorrhizal plants in response to the multiple benefits (e.g., improved nutrition and stress resistance) provided by the association. In this work, we analyzed the bacterial communities associated with the rhizosphere of plants and their response to mycorrhizae in low P conditions. Methods: For this purpose, inoculated and non-inoculated B73 corn plants were grown with a consortium of mycorrhizal fungi under low phosphorus conditions. Mycorrhiza response in B73 and the interaction with rhizosphere microbiome were characterized by sequencing the bacterial 16S rRNA gene. Results: Inoculated plants showed increased greater growth in leaf and root parameters in low P conditions. Bacterial microbiome showed changes in beta diversity and some OUTs significantly regulated by AMF presence. Conclusion: These data confirm the importance of mycorrhizae in phosphorus stress and rhizosphere community changes as a possible mechanism to improve plant growth. [ABSTRACT FROM AUTHOR]

Aim Location Taxon Methods Results Main Conclusion We used two fungal data sources for occurrence records (fruitbodies and roots) to (1) test the influence of data source on estimating the environmental niche of ectomycorrhizal (ECM) fungi and (2) compare the differences in estimated niche area and density for ECM fungal species with conspicuous (easily observed, i.e. mushrooms) versus inconspicuous (difficult to observe and/or usually overlooked, i.e. crusts and truffles) fruitbodies.Europe.Sixty‐six ectomycorrhizal fungi.We used fungal records obtained from fruitbody and root data of 66 common ECM fungal species in European forests to estimate their environmental niches. The fruitbody data were extracted from public databases (GBIF, UNITE), while the root data (from individual ectomycorrhizas) were obtained from a dataset of 136 ICP Forests long‐term intensive monitoring plots. We estimated the niches for combined data sources (fruitbody and root data) and for each individual data source using six key environmental variables for ECM fungal community composition. We then examined how estimated niche overlap and area (number of cells in niche grid) varied for the two data sources between conspicuous and inconspicuous species.We found that although the niches estimated using combined data from the two data sources had high overlap with the niches estimated from fruitbody data, the niches estimated from fruitbody data had low or medium overlap with the niches estimated using root data for most ECM fungi. The overlap between the two data sources for conspicuous species was significantly larger than that for inconspicuous species. Root data were important for estimating the niche of inconspicuous species, which had a high ratio of root data to fruitbody data.Our results indicate that although fruitbody data suffice for estimating the environmental niche for most conspicuous ECM fungi, combined datasets including fruitbody and root data can improve the accuracy of estimated niches and should be used. Root data for inconspicuous species are particularly useful, and thus, adopting root data in niche estimation will better infer the niches of ECM fungi. Inferring niches along environmental variables can guide future sampling and conservation of fungi. [ABSTRACT FROM AUTHOR]

Summary: Nutrient limitation may constrain the ability of recovering and mature tropical forests to serve as a carbon sink. However, it is unclear to what extent trees can utilize nutrient acquisition strategies – especially root phosphatase enzymes and mycorrhizal symbioses – to overcome low nutrient availability across secondary succession.Using a large‐scale, full factorial nitrogen and phosphorus fertilization experiment of 76 plots along a secondary successional gradient in lowland wet tropical forests of Panama, we tested the extent to which root phosphatase enzyme activity and mycorrhizal colonization are flexible, and if investment shifts over succession, reflective of changing nutrient limitation. We also conducted a meta‐analysis to test how tropical trees adjust these strategies in response to nutrient additions and across succession.We find that tropical trees are dynamic, adjusting investment in strategies – particularly root phosphatase – in response to changing nutrient conditions through succession. These changes reflect a shift from strong nitrogen to weak phosphorus limitation over succession. Our meta‐analysis findings were consistent with our field study; we found more predictable responses of root phosphatase than mycorrhizal colonization to nutrient availability.Our findings suggest that nutrient acquisition strategies respond to nutrient availability and demand in tropical forests, likely critical for alleviating nutrient limitation. [ABSTRACT FROM AUTHOR]

Epiphytism is an example of an obligate interspecific interaction between plants, where a plant species grows on another plant species for physical support. In epiphytic orchids that rely on suitable host tree species (phorophytes) and mycorrhizal fungi for germination and growth, a distinct preference has been observed for particular host tree species. However, the factors driving this host preference remain unclear.In this study, we investigated whether mycorrhizal fungi that promote seedling development determine the preference of phorophytes in the epiphytic orchid Dendrobium wangliangii. First, we identified the preferred host tree species for this orchid. Next, in vitro and in situ germination experiments were conducted to identify potential fungi that promote seed germination. Finally, high‐throughput sequencing was used to assess the distribution of these fungi on both colonized host trees and potential host trees, including individual trees of the host species not yet colonized by the orchid and trees of another species growing in the vicinity of a colonized tree.Dendrobium wangliangii exhibited a preference for trees within the Fagaceae family. Two Fusarium species from the bark of host trees were identified as the primary fungi that promote seed germination. Successful protocorm formation and seedling development were observed exclusively on preferred phorophytes. Fungal community analyses further indicated that both Fusarium spp. occurred on all potential host trees, suggesting that the host preference of this epiphytic orchid is not constrained by the distribution of suitable mycorrhizal fungi.Synthesis: Regarding the epiphytes that depend on mycorrhizal fungi for successful seedling recruitment, we conclude that strong epiphyte–phorophyte associations do not arise from the limited distribution of mycorrhizal fungi but are more likely the result of other factors inherent in the phorophyte environment. [ABSTRACT FROM AUTHOR]

Aim We investigated whether there was interspecies and intraspecies variation in spore germination of 12 strains of arbuscular mycorrhizal fungi when co-entrapped with the diazotrophic plant growth-promoting bacteria, Azospirillum brasilense Sp7 in alginate hydrogel beads. Methods and results Twelve Rhizophagus irregularis, Rhizophagus intraradices , and Funneliformis mosseae strains were separately combined with a live culture of Azospirillum brasilense Sp7. Each fungal–bacterial consortia was supplemented with sodium alginate to a 2% concentration (v/v) and cross-linked in calcium chloride (2% w/v) to form biodegradable hydrogel beads. One hundred beads from each combination (total of 1200) were fixed in solidified modified Strullu and Romand media. Beads were observed for successful spore germination and bacterial growth over 14 days. In all cases, successful growth of A. brasilense was observed. For arbuscular mycorrhizal fungi, interspecies variation in spore germination was observed, with R. intraradices having the highest germination rate (64.3%), followed by R. irregularis (45.5%) and F. mosseae (40.3%). However, a difference in intraspecies germination was only observed among strains of R. irregularis and F. mosseae. Despite having varying levels of germination, even the strains with the lowest potential were still able to establish with the plant host Brachypodium distachyon in a model system. Conclusions Arbuscular mycorrhizal spore germination varied across strains when co-entrapped with a diazotrophic plant growth-promoting bacteria. This demonstrates that hydrogel beads containing a mixed consortium hold potential as a sustainable biofertilizer and that compatibility tests remain an important building block when aiming to create a hydrogel biofertilizer that encases a diversity of bacteria and fungi. Moving forward, further studies should be conducted to test the efficacy of these hydrogel biofertilizers on different crops across varying climatic conditions in order to optimize their potential. [ABSTRACT FROM AUTHOR]

We assessed the impact of road disturbances on the dominant mycorrhizal types in ecosystems at the global level and how this mechanism can potentially lead to lasting plant community changes. We used a database of coordinated plant community surveys following mountain roads from 894 plots in 11 mountain regions across the globe in combination with an existing database of mycorrhizal–plant associations in order to approximate the relative abundance of mycorrhizal types in natural and disturbed environments. Our findings show that roadside disturbance promotes the cover of plants associated with arbuscular mycorrhizal (AM) fungi. This effect is especially strong in colder mountain environments and in mountain regions where plant communities are dominated by ectomycorrhizal (EcM) or ericoid‐mycorrhizal (ErM) associations. Furthermore, non‐native plant species, which we confirmed to be mostly AM plants, are more successful in environments dominated by AM associations. These biogeographical patterns suggest that changes in mycorrhizal types could be a crucial factor in the worldwide impact of anthropogenic disturbances on mountain ecosystems. Indeed, roadsides foster AM‐dominated systems, where AM‐fungi might aid AM‐associated plant species while potentially reducing the biotic resistance against invasive non‐native species, often also associated with AM networks. Restoration efforts in mountain ecosystems will have to contend with changes in the fundamental make‐up of EcM‐ and ErM plant communities induced by roadside disturbance. [ABSTRACT FROM AUTHOR]

In his seminal paper, Göte Turesson proposed the term ecotype as the 'ecological unit to cover the product arising as a result of the genotypical response of an ecospecies to a particular habitat'. Turesson further outlined that to fully understand the ecology of a species, a knowledge of its most important ecotypes is needed. Whereas Turesson's original idea of an ecotype mainly referred to the response of a species to abiotic conditions, there is mounting evidence that ecotypes can also originate as a response to biotic conditions. Hence, to understand the ecology of a species, one should also understand the distribution and variation in biotic interactions. For plants, one such biotic interaction involves mycorrhizal fungi. Particularly in mycoheterotrophic plants, i.e. plants that rely on mycorrhizal fungi for their carbon supply, adaptation to and specialization on mycorrhizal fungi have the potential to drive ecotype formation and speciation. In this paper, we provide evidence that populations of mycoheterotrophic plants inhabiting contrasting habitats commonly encounter divergent mycorrhizal fungal communities leading to geographic mosaics of mycorrhizal interactions. Adaptation to local fungal communities, in turn, can induce (partial) reproductive isolation and contribute to ecotype and ultimately species formation as a result of decreased fitness of immigrant genotypes (immigrant inviability). In the most extreme case, loss of photosynthesis and mycorrhizal switching have led to reproductive isolation and the development of novel species that have become fully mycoheterotrophic. Such shifts have occurred repeatedly during the evolutionary history of land plants. We conclude that mycorrhizal fungi not only contribute to the early divergence of populations of mycoheterotrophic plants, but also play a crucial role in the further diversification and origination of this unique set of species that rely on mycorrhizal fungi for obtaining carbon and completing their life cycle. [ABSTRACT FROM AUTHOR]

Orchids produce millions of dust-like and reserveless tiny seeds per capsule and are unable to germinate on their own in nature. Orchid seeds have developed strategies to exploit seed germination-promoting orchid mycorrhizal fungi (sgOMFs) for acquisition of exogenous nutrients to fuel germination. Once colonized by sgOMFs, orchid seeds can digest intracellular sgOMF hyphae to acquire fungal nutrients, especially those for carbon nutrition. However, the underlying carbon delivery pathway from sgOMFs to orchid cells remains elusive. Clarification of the identities of fungally derived carbohydrates and the main molecular players responsible for the sgOMF-to-orchid carbon flow is of great significance for better understanding of symbiotic germination. To germinate in nature, orchid seeds strictly rely on seed germination-promoting orchid mycorrhizal fungi (sgOMFs) for provision of carbon nutrients. The underlying delivery pathway, however, remains elusive. We develop here a plausible model for sugar transport from sgOMFs to orchid embryonic cells to fuel germination. Orchids exploit sgOMFs to induce the formation of pelotons, elaborate intracellular hyphal coils in orchid embryos. The colonized orchid cells then obtain carbon nutrients by uptake from living hyphae and peloton lysis, primarily as glucose derived from fungal trehalose hydrolyzed by orchid-specific trehalases. The uptake of massive fungally derived glucose is likely to be mediated by two classes of membrane proteins, namely, sugars will eventually be exported transporters (SWEETs) and H+-hexose symporters. The proposed model serves as a launch pad for further research to better understand and improve orchid seed germination and conservation. [ABSTRACT FROM AUTHOR]

Background and Aims Plants have adapted to acquire phosphorus (P) primarily through advantageous root morphologies, responsive physiological pathways and associations with mycorrhizal fungi. Yet, to date, little information exists on how variation in arbuscular mycorrhizal (AM) colonization is coordinated with root morphological and physiological traits to enhance P acquisition. Methods Thirteen root functional traits associated with P acquisition were characterized at full bloom stage in pot cultures under low soil P availability conditions for 13 soybean genotypes contrasting in AM colonization. Key Results Significant variation in root functional traits was observed in response to low P stress among the 13 tested soybean genotypes contrasting in AM colonization. Genotypes with low AM colonization exhibited greater root proliferation but with less advantageous root physiological characteristics for P acquisition. In contrast, genotypes with high AM colonization exhibited less root growth but higher phosphatase activities and carboxylate content in the rhizosheath. Root dry weights, and contents of carbon and P were positively correlated with root morphological traits of different root orders and whole root systems, and were negatively correlated with AM colonization of fine roots and whole root systems, as well as rhizosheath phosphatase activities and carboxylate contents. These results taken in combination with a significant positive correlation between plant P content and root morphological traits indicate that root morphological traits play a primary role in soybean P acquisition. Conclusions The results suggest that efficient P acquisition involves tradeoffs among carbon allocation to root proliferation, mycorrhizal symbiosis or P-mobilizing exudation. Complementarity and complexity in the selection of P acquisition strategies was notable among soybean genotypes contrasting in AM colonization, which is closely related to plant C budgeting. [ABSTRACT FROM AUTHOR]

Premise: While many studies have measured the aboveground responses of plants to mycorrhizal fungi at a single time point, little is known about how plants respond belowground or across time to mycorrhizal symbiosis. By measuring belowground responses and growth over time in many plant species, we create a more complete picture of how mycorrhizal fungi benefit their hosts. Methods: We grew 26 prairie plant species with and without mycorrhizal fungi and measured 14 functional traits to assess above‐ and belowground tissue quality and quantity responses and changes in resource allocation. We used function‐valued trait (FVT) modeling to characterize changes in species growth rate when colonized. Results: While aboveground biomass responses were positive, the response of traits belowground were much more variable. Changes in aboveground biomass accounted for 60.8% of the variation in mycorrhizal responses, supporting the use of aboveground biomass response as the primary response trait. Responses belowground were not associated with aboveground responses and accounted for 18.3% of the variation. Growth responses over time were highly variable across species. Interestingly, none of the measured responses were phylogenetically conserved. Conclusions: Mycorrhizal fungi increase plant growth in most scenarios, but the effects of these fungi belowground and across time are more complicated. This study highlights how differences in plant allocation priorities might affect how they utilize the benefits from mycorrhizal fungi. Identifying and characterizing these differences is a key step to understanding the effects of mycorrhizal mutualisms on whole plant physiology. [ABSTRACT FROM AUTHOR]

Predicting how biological communities assemble in restored ecosystems can assist in conservation efforts, but most research has focused on plants, with relatively little attention paid to soil microbial organisms that plants interact with. Arbuscular mycorrhizal (AM) fungi are an ecologically significant functional group of soil microbes that form mutualistic symbioses with plants and could therefore respond positively to plant community restoration. To evaluate the effects of plant community restoration on AM fungi, we compared AM fungal abundance, species richness, and community composition of five annually cultivated, conventionally managed agricultural fields with paired adjacent retired agricultural fields that had undergone prairie restoration 5–9 years prior to sampling. We hypothesized that restoration stimulates AM fungal abundance and species richness, particularly for disturbance‐sensitive taxa, and that gains of new taxa would not displace AM fungal species present prior to restoration due to legacy effects. AM fungal abundance was quantified by measuring soil spore density and root colonization. AM fungal species richness and community composition were determined in soils and plant roots using DNA high‐throughput sequencing. Soil spore density was 2.3 times higher in restored prairies compared to agricultural fields, but AM fungal root colonization did not differ between land use types. AM fungal species richness was 2.7 and 1.4 times higher in restored prairies versus agricultural fields for soil and roots, respectively. The abundance of Glomeraceae, a disturbance‐tolerant family, decreased by 25% from agricultural to restored prairie soils but did not differ in plant roots. The abundance of Claroideoglomeraceae and Diversisporaceae, both disturbance‐sensitive families, was 4.6 and 3.2 times higher in restored prairie versus agricultural soils, respectively. Species turnover was higher than expected relative to a null model, indicating that AM fungal species were gained by replacement. Our findings demonstrate that restoration can promote a relatively rapid increase in the abundance and diversity of soil microbial communities that had been degraded by decades of intensive land use, and community compositional change can be predicted by the disturbance tolerance of soil microbial taxonomic and functional groups. [ABSTRACT FROM AUTHOR]

Pyrolysis temperature is a key factor that determines the characteristics of biochar and nutrient availability. However, little is known about how pyrolysis temperature affects phosphorus (P) bioavailability and uptake as well as the underlying mechanism when poultry litter biochar (PB), or its combination with NPK, is applied as a soil amendment on peri-urban cropland. To determine the influence of low and high pyrolysis temperatures on PB and its impact on P bioavailability, uptake and maize yield, we set up a randomized block design field study with the following treatments: (i) No amendment (CK), (ii) NPK mineral fertilization, (iii) biochar pyrolyzed at 300 °C (PB300), (iv) biochar pyrolyzed at 600 °C (PB600), (v) PB300 + NPK, and (vi) PB600 + NPK. Our results demonstrate that differences in pyrolysis temperatures (300 °C) — low and (600 °C) — high at which PB was pyrolyzed had no controlling influence on P bioavailability, uptake, soil microbial biomass P, alkaline phosphatase enzyme activity, mycorrhizal fungi components (spores, colonization, glomalin, mycelium density), and maize yield. Similarly, regardless of pyrolysis temperature differences, the combination of PB with NPK (PB300 + NPK and PB600 + NPK) significantly (p < 0.05) increased soil P availability by 24% and 13%, uptake 46% and 42%, soil microbial biomass P 63% and 60%, C 8% and 2%, alkaline phosphatase 58% and 37%, and maize yield 37% and 36%, respectively, compared with NPK. PB + NPK, regardless of pyrolysis temperature, retained more P from total P input, which indicates that PB could be a veritable soil amendment technology for mitigating P leaching and enhancing P use efficiency and recycling on peri-urban croplands. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of Botanical Research is the property of Bulletin of Botanical Research Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Lactarius hatsudake Tanaka is a mycorrhizal edible mushroom with an appealing taste and rich nutrition. It is also a significant food and has medicinal value. In this study, the plantation of L. hatsudake during the harvest period was taken as the research object, and this article explores which bacteria in the soil contribute to the production and growth of L. hatsudake. The soil of the control (CK) and the soil of the mushroom-producing area [including the soil of the base of the mushroom (JT) and the mycorrhizal root soil (JG)] was collected in the plantation. The three sites' bacterial community structure and soil diversity were analyzed using high-throughput sequencing technology, and a molecular ecological network was built. Soil bacteria in the L. hatsudake plantation had 28 tribes, 74 classes, 161 orders, 264 families, 498 genera, and 546 species. The dominant phyla were Proteobacteria and Acidobacteria, and the dominant genera were Burkholderia_Caballeronia_Paraburkholderia, Acidothermus, Bradyrhizobium, Candidatus_Xiphinematobacter, and Granulicella. The α-diversity of soil bacteria in JT was significantly lower than that in JG and CK, and the β-diversity in JT samples was significantly different from that in JG and CK samples. The size and complexity of the constructed network were smaller in JT samples than in JG and CK samples, and the stability was higher in JT samples than in JG and CK samples. The positive correlation between species in JT samples was dominant. The potential mycorrhizal helper bacteria (MHB) species of L. hatsudake was determined using correlation and differential group analysis. The results support future research on mycorrhizal synthesis, plantation management, and the function of microorganisms in the soil rhizosphere of L. hatsudake. [ABSTRACT FROM AUTHOR]

Mycoheterotrophy, whereby plants acquire both carbon and nutrients from a fungal partner, is an evolutionarily puzzling phenomenon. According to biological market models, mycoheterotrophs have nothing to offer and thus should be shunned as trading partners by discriminating fungi. Nevertheless, mycoheterotrophy is common, particularly among orchids, and an estimated 10% of all plant species are facultatively mycoheterotrophic at early stages in their life cycle. Reconciling mycoheterotrophy with biological market models, I describe how mycoheterotrophs could use arbitrage trading to net a profit of carbon and nutrients, without acquiring either from the abiotic environment. The model requires that mycoheterotrophs simultaneously buy and sell both carbon and nutrients, exploiting variability in the trading ratios offered by mycorrhizal fungi. The model relies on several conditions, including the ability of the mycoheterotroph to form indirect hyphal associations with two or more neighbouring autotrophic mycorrhizal associations, the existence of variable carbon:nutrient exchange ratios among these associations and the ability of mycoheterotrophs to invert the net‐direction of resource trade. Evidence that these conditions occur in a state of nature varies from incontrovertible to plausible given available models. The arbitrage model provides evolutionary rationale for mycoheterotrophy from both the plant and fungal perspective. Accordingly, mycoheterotrophs match trading ratios offered by autotrophic plants and, thus, need not be antagonists. The model makes novel predictions that distinguish it from source‐sink models, most notably in the existence of resource exchange inversions at the plant‐mycorrhizal interface. Finally, the model emphasizes market inefficiencies as the foundation on which mycoheterotrophs construct an arbitrage niche. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Organic production systems are increasingly gaining market share; however, there are still few studies on their influence on the activity of soil microorganisms in sugarcane. Arbuscular mycorrhizal fungi are extremely sensitive to environmental changes, and their activity can be used as a parameter of comparison and quality between organic and conventional systems. The objective of this work was to evaluate mycorrhizal activity in different varieties of sugarcane under two production systems. This work was carried out in a commercial plantation of the Jalles Machado plant in the municipality of Goianésia in Goiás, Brazil. The values of spore density in the soil, mycorrhizal colonization rate in the roots and easily extractable glomalin were evaluated, and the associated fungal species were identified. There was no effect of sugarcane variety on the number of spores or the glomalin content in the soil. The conventional system presented significantly lower mycorrhizal colonization rates than did the organic system. The varieties cultivated under the conventional planting system showed a greater diversity of arbuscular mycorrhizal fungi, where 12 of the 13 different species of mycorrhizal fungi found in both cultivation systems occurred. [ABSTRACT FROM AUTHOR]

Introduction: Ferns constitute the second largest group of vascular plants. Previous studies have shown that the diversity and composition of fern communities are influenced by resource availability and water stress, among other factors. However, little is known about the influence of these environmental factors on their biotic interactions, especially regarding the relationship between mycorrhizal fungi and ferns. The present study compares the mycorrhizal communities associated with 36 populations of Struthiopteris spicant L. Weiss across Europe and North America. This species exhibits a great tolerance to variations in light, nutrient, and pH conditions, and it can survive with and without mycorrhizae. Methods: With the aim of determining which environmental factors impact the composition and abundance of the root-associated fungal communities in this species, we used an ITS-focused metabarcoding approach to identify the mycorrhizal fungi present and analyzed the influence of climatic and edaphic variables at global and regional scales Results and discussion: We encountered striking differences in the relative abundance of arbuscular mycorrhizal fungi (AMF) between S. spicant populations at both spatial levels. We recorded a total of 902 fungal ASVs, but only 2– 4% of the total fungal diversity was observed in each individual, revealing that each fern had a unique fungal community. Light availability and the interactive action of pH and soil nitrogen concentration showed a positive influence on AMF relative abundance, explaining 89% of the variance. However, environmental factors could only explain 4– 8% of the variability in AMF community composition, indicating that it might be determined by stochastic processes. These results support the hypothesis that ferns may be more independent of mycorrhization than other plant groups and interact with fungi in a more opportunistic manner. [ABSTRACT FROM AUTHOR]

Summary: It has been proposed that ectomycorrhizal fungi can reduce decomposition while arbuscular mycorrhizal fungi may enhance it. These phenomena are known as the 'Gadgil effect' and 'priming effect', respectively. However, it is unclear which one predominates globally.We evaluated whether mycorrhizal fungi decrease or increase decomposition, and identified conditions that mediate this effect. We obtained decomposition data from 43 studies (97 trials) conducted in field or laboratory settings that controlled the access of mycorrhizal fungi to substrates colonized by saprotrophs.Across studies, mycorrhizal fungi promoted decomposition of different substrates by 6.7% overall by favoring the priming effect over the Gadgil effect. However, we observed significant variation among studies. The substrate C : N ratio and absolute latitude influenced the effect of mycorrhizal fungi on decomposition and contributed to the variation. Specifically, mycorrhizal fungi increased decomposition at low substrate C : N and absolute latitude, but there was no discernable effect at high values. Unexpectedly, the effect of mycorrhizal fungi was not influenced by the mycorrhizal type.Our findings challenge previous assumptions about the universality of the Gadgil effect but highlight the potential of mycorrhizal fungi to negatively influence soil carbon storage by promoting the priming effect. [ABSTRACT FROM AUTHOR]

Ectomycorrhizal fungi and non-ectomycorrhizal fungi are responsive to changes in environmental and nutrient availabilities. Although many species of ectomycorrhizas are known to enhance the uptake of phosphorus and other nutrients for Pinus taeda, it is not understood how to optimize these communities to have tangible effects on plantation silviculture and P use efficiency. The first step of this process is the identification of native fungi present in the system that are associated with P. taeda and influence P uptake efficiency. We used sand-filled mesh bags baited with finely ground apatite to sample ectomycorrhizal and non-ectomycorrhizal fungi associated with the rhizosphere of P-responsive P. taeda under several field conditions. Mesh bags were assessed for biomass accumulation over three years using a single three-month burial period pre-harvest and three six-month burial periods post-planting. Amplicon sequencing assessed ectomycorrhizal and non-ectomycorrhizal communities between phosphorus treatments, sites, mesh bags, and the rhizosphere of actively growing P. taeda in the field. We found biomass accumulation within the mesh bags was inversely related to increasing phosphorus fertilization (carryover) rates from pre-harvest to postplanting. Up to 25% increases in total biomass within the bags were observed for bags baited with P. Taxonomic richness was highest in Alfisol soils treated with phosphorus from the previous rotation and lowest in the Spodosol regardless of phosphorus treatment. [ABSTRACT FROM AUTHOR]

The utilization of saline water for irrigating plants in arid and semi-arid regions has become imperative because of the scarcity of water resources. Nevertheless, under salt stress conditions, plants undergo a multitude of variation, which result in delayed growth and adversely affect the plant metabolism. Adopting appropriate and sustainable strategies such as using bio-organic fertilizers from animal and plant waste or integrating microorganisms (symbiotic fungi), can improve plant resilience against salt stress. The purpose of this study was to elucidate the impact of arbuscular mycorrhizal fungus (AMF) Rhizophagus irregularis alone and/or combined with compost on growth, nutrient uptake, antioxidant activities, and photosynthesis-related performance of Stevia rebaudiana Bertoni under salt stress conditions. Salt stress negatively affected all studied parameters. However, the application of R. irregulare strain in a substrate amended with 5% compost is more effective in enhancing salt stress tolerance in stevia plants compared to the compost and AMF strain applied separately. The synergistic effect of the co-application of these two biofertilizers under salt stress resulted in increased stomatal conductance (276%), chlorophyll fluorescence (38%), antioxidant enzyme activities, and the uptake of K+ (78%), Ca2+ (117%), and P (149%). In conclusion, the application of compost combined with AMF may be a promising sustainable strategy for improving salt stress resistance in stevia. [ABSTRACT FROM AUTHOR]

Our study delved into the relationship between root‐associated fungi, gene expression and plant morphology in Norway spruce cuttings derived from both slow‐and fast‐growing trees. We found no clear link between the gene expression patterns of adventitious roots and the growth phenotype, suggesting no fundamental differences in the receptiveness to fungal symbionts between the phenotypes. Interestingly, saplings from slow‐growing parental trees exhibited a higher richness of ectomycorrhizal species and larger roots. Some ectomycorrhizal species, typically found on mature spruces, were more prevalent on saplings from slow‐growing spruces. The ericoid mycorrhizal fungus, Hyaloscypha hepaticola, showed a stronger association with saplings from fast‐growing spruces. Moreover, saplings from slow‐growing spruces had a greater number of Ascomycete taxa and free‐living saprotrophic fungi. Aboveground sapling stems displayed some phenotypic variation; saplings from fast‐growing phenotypes had longer branches but fewer whorls in their stems compared to those from the slow‐growing group. In conclusion, the observed root‐associated fungi and phenotypic characteristics in young Norway spruces may play a role in their long‐term growth rate. This suggests that the early interactions between spruces and fungi could potentially influence their growth trajectory. [ABSTRACT FROM AUTHOR]

Summary: Neottia ovata (twayblade) is illustrated here (t. 1099). It is a widespread, temperate Eurasian species. A detailed description is provided, with notes on cytology and habitat. Given its wide distribution and the diverse range of habitats where it occurs, its conservation status is Least Concern in Europe. Probably as a reflection of its dependence on mycorrhizal fungi for its whole life history, it is not a plant known from cultivation; it should be enjoyed as an intriguing member of our native orchid flora. [ABSTRACT FROM AUTHOR]

The tree species Salix caprea shows high adaptability to different habitat conditions and is economically valuable as a woody crop for biomass production. Moreover, S. caprea is dependent on mycorrhizal fungi, which are crucial for its growth and adaptability in different environments. Hence, this study explores the ectomycorrhizal diversity of S. caprea by utilizing the taxonomy (morphotyping and a molecular approach using the ITS and LSU regions) and trait diversity (exploration types) at two test sites in Germany and Poland. In total, 19 ectomycorrhizal (EM) morphotypes of S. caprea were characterized. Seven taxa were identified at the species level (Hebeloma populinum, Cortinarius atrocoerulaeus, Inocybe hirtella, Laccaria cf. ochropurpurea, Tuber maculatum, Cenococcum geophilum, and Phialophora finlandia) and twelve at the genus level (Tomentella spp. 1–8, Hebeloma sp. 1, Inocybe sp. 1, and Tuber spp. 1–2). The EM colonization ranged from 14 to 28% of the fine root tips. At both test sites, the largest portion of the total EM colonization consisted of Thelephoraceae. The exploration types were classified as medium-distance smooth (Tomentella sp. 1–8 and L. ochropurpurea) and medium-distance fringe (C. atrocoerulaeus), while the other taxa were short-distance exploration types, highlighting their potential functional role in the adaptation and growth of S. caprea. [ABSTRACT FROM AUTHOR]

Dendrobium officinale Kimura & Migo in the genus Dendrobium of Orchidaceae is an important medicinal plant that produces various bibenzyl and phenanthrene derivatives. In some orchids, these derivatives have been reported to increase with fungal infection. Bibenzyl biosynthesis is regulated by bibenzyl synthase (BBS). Although six genes of the BBS family have been registered from D. officinale, their gene regulation mechanisms are unclear. The infection of Dendrobium with mycorrhizal fungi also reportedly increases the expression of genes involved in biosynthesis; however, the effect of mycorrhizal fungi on bibenzyl production is unknown. The present study examined the effects of three mycorrhizal fungi isolated from D. officinale on BBS gene expression and bibenzyl production over time. One of the Tulasnellaceae operational taxonomic units induced BBS gene expression and increased two representative bibenzyls, gigantol and dendrophenol, at specific time points. Furthermore, 19 BBS sequences were cloned from 12 Dendrobium species, and a phylogenetic analysis was performed. The results indicated that repeated BBS gene duplication occurred during the evolution of the genus, and further duplication occurred after speciation. These results suggest that it is possible to optimize metabolite production by selecting suitable symbiotic fungi. [ABSTRACT FROM AUTHOR]

Nitrogen (N) immobilization (Nim, including microbial N assimilation) and plant N uptake (PNU) are the two most important pathways of N retention in soils. The ratio of Nim to PNU (hereafter Nim:PNU ratio) generally reflects the degree of N limitation for plant growth in terrestrial ecosystems. However, the key factors driving the pattern of Nim:PNU ratio across global ecosystems remain unclear. Here, using a global data set of 1018 observations from 184 studies, we examined the relative importance of mycorrhizal associations, climate, plant, and soil properties on the Nim:PNU ratio across terrestrial ecosystems. Our results show that mycorrhizal fungi type (arbuscular mycorrhizal (AM) or ectomycorrhizal (EM) fungi) in combination with soil inorganic N mainly explain the global variation in the Nim:PNU ratio in terrestrial ecosystems. In AM fungi‐associated ecosystems, the relationship between Nim and PNU displays a weaker negative correlation (r = −.06, p <.001), whereas there is a stronger positive correlation (r =.25, p <.001) in EM fungi‐associated ecosystems. Our meta‐analysis thus suggests that the AM‐associated plants display a weak interaction with soil microorganisms for N absorption, while EM‐associated plants cooperate with soil microorganisms. Furthermore, we find that the Nim:PNU ratio for both AM‐ and EM‐associated ecosystems gradually converge around a stable value (13.8 ± 0.5 for AM‐ and 12.1 ± 1.2 for EM‐associated ecosystems) under high soil inorganic N conditions. Our findings highlight the dependence of plant–microbial interaction for N absorption on both plant mycorrhizal association and soil inorganic N, with the stable convergence of the Nim:PNU ratio under high soil N conditions. [ABSTRACT FROM AUTHOR]

The genus Laccaria (Hydnangiaceae, Agaricales) is an important ectomycorrhizal symbiont of a broad range of host plants. Laccaria guizhouensis was collected from a subtropical mixed forest dominated by Fagaceae in Southwest China and described based on morphological characteristics and molecular data. Laccaria guizhouensis is characterised by its medium-sized basidiocarps and strong striate or sulcatus, flesh-coloured to brown pileus, flesh-coloured to brown lamellae, 2- to 4-spored basidia, globose to obellipsoid, hyaline, moderately echinulate basidiospores, and 1–1.5 μm-long echinulate. Phylogenetic analyses based on ITS sequences (HMAS352265 and HMAS352266) indicated that L. guizhouensis represented a new species separated from all other Laccaria species. [ABSTRACT FROM AUTHOR]

The phytohormones strigolactones (SLs) control root and shoot branching and are exuded from roots into the rhizosphere to stimulate interaction with mycorrhizal fungi. The exuded SLs serve as signaling molecules for the germination of parasitic plants. The broomrape Phelipanche aegyptiaca is a widespread noxious weed in various crop plants, including tomato (Solanum lycopersicum). We have isolated three mutants that impair SL functioning in the tomato variety M82: SHOOT BRANCHING 1 (sb1) and SHOOT BRANCHING 2 (sb2), which abolish SL biosynthesis, and SHOOT BRANCHING 3 (sb3), which impairs SL perception. The over-branching phenotype of the sb mutants resulted in a severe yield loss. The isogenic property of the mutations in a determinate growth variety enabled the quantitative evaluation of the contribution of SL to yield under field conditions. As expected, the mutants sb1 and sb2 were completely resistant to infection by P. aegyptiaca due to the lack of SL in the roots. In contrast, sb3 was more susceptible to P. aegyptiaca than the wild-type M82. The SL concentration in roots of the sb3 was two-fold higher than in the wild type due to the upregulation of the transcription of SL biosynthesis genes. This phenomenon suggests that the steady-state level of root SLs is regulated by a feedback mechanism that involves the SL signaling pathway. Surprisingly, grafting wild-type varieties on sb1 and sb2 rootstocks eliminated the branching phenotype and yield loss, indicating that SL synthesized in the shoots is sufficient to control shoot branching. Moreover, commercial tomato varieties grafted on sb1 were protected from P. aegyptiaca infection without significant yield loss, offering a practical solution to the broomrape crisis. [ABSTRACT FROM AUTHOR]

Drought affects several plant physiological characteristics such as photosynthesis, carbon metabolism, and chlorophyll content, causing hormonal and nutritional imbalances and reducing nutrient uptake and transport, which inhibit growth and development. The use of bioinoculants based on plant growth-promoting microorganisms such as plant growth-promoting rhizobacteria (PGPR), yeasts, and arbuscular mycorrhizal fungi (AMF) has been proposed as an alternative to help plants tolerate drought. However, most studies have been based on the use of a single type of microorganism, while consortia studies have been scarcely performed. Therefore, the aim of this study was to evaluate different combinations of three PGPR, three AMF, and three yeasts with plant growth-promoting attributes to improve the biochemical, nutritional, and physiological behavior of strawberry plants growing under severe drought. The results showed that the growth and physiological attributes of the non-inoculated plants were significantly reduced by drought. In contrast, plants inoculated with the association of the fungus Claroideoglomus claroideum, the yeast Naganishia albida, and the rhizobacterium Burkholderia caledonica showed a stronger improvement in tolerance to drought. High biomass, relative water content, fruit number, photosynthetic rate, transpiration, stomatal conductance, quantum yield of photosystem II, N concentration, P concentration, K concentration, antioxidant activities, and chlorophyll contents were significantly improved in inoculated plants by up to 16.6%, 12.4%, 81.2%, 80%, 79.4%, 71.0%, 17.8%, 8.3%, 6.6%, 57.3%, 41%, and 22.5%, respectively, compared to stressed non-inoculated plants. Moreover, decreased malondialdehyde levels by up to 32% were registered. Our results demonstrate the feasibility of maximizing the effects of inoculation with beneficial rhizosphere microorganisms based on the prospect of more efficient combinations among different microbial groups, which is of interest to develop bioinoculants oriented to increase the growth of specific plant species in a global scenario of increasing drought stress. [ABSTRACT FROM AUTHOR]

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Tomato production in the Canary Islands has significantly decreased in recent years due to the presence of parasites and pathogens, poor-quality irrigation water, lack of infrastructure modernization, and increased competition. To address this issue, local varieties with better agro-climatic adaptation and organoleptic characteristics have been cultivated. These varieties show their maximum potential under an agro-ecological cultivation system, where the beneficial micro-organisms of the rhizosphere (in general) and mycorrhizal fungi (in particular) have a positive influence on their development, especially when the plants are subjected to biotic or abiotic stresses. Irrigation water in Canary Islands tomato cultivation comes from groundwater sources with moderate levels of sodium and chlorides or sodium and bicarbonates. This study evaluated the response of mycorrizal plants of the local tomato variety "Manzana Negra" under abiotic stress conditions due to the presence of chlorides and bicarbonates. Two tests were carried out with mycorrhizal and non-mycorrhizal plants. In the first one, 0, 75, and 150 mM NaCl solutions were applied. In the second, the nutrient solution was enriched with sodium bicarbonate at doses of 0, 2.5, 5, 7.5, 10, and 12.5 mM. Presence of native mycorrhizae improved the growth and nutrition of plants affected by irrigation with saline and alkaline water containing chloride and sodium carbonate. Symbiosis produced statistically significant increases in all plant-development-related variables (stem length and diameter; fresh and dry weight) in all bicarbonate concentrations. However, the results with the application of sodium chloride do not seem to indicate a positive interaction in most of the analytical parameters at 150 mM NaCl concentration. The mycorrhizal inoculation with local fungi can be interesting in the production of seedlings of this tomato variety in situations of moderate salinity, especially under bicarbonate stress conditions. [ABSTRACT FROM AUTHOR]