Fig 1 - uploaded by Jesse J Sadowsky
Content may be subject to copyright.
Mycelium of Agrocybe praecox strain AER-1 in a substrate amended with pine litter, bark and wood ( a ), forming mycelial cords in the rhizosphere of highbush blueberry ( b ). Bar 0 1 cm
Source publication
Aims
Ericoid mycorrhizal (ErM) fungi and other ericaceous root symbionts do not completely degrade lignin, therefore the presence of lignin in organic residues may present a barrier to nutrient uptake by ericaceous plants. Due to specialization of ErM and saprotrophic, lignin-degrading fungi in litter decomposition and nutrient mobilization, we hyp...
Context in source publication
Context 1
... length was assessed 3, 14, and 30 months after the start of the experiment. In 2007, some plants produced fruits and their number was recorded for each inoculation treatment. Plants were destructively harvested in October 2008. Shoots and roots were separated from roots, dried for 5 h at 70°C and 1 h at 90°C and weighed. Shoot K, Ca, Mg, P, N and C content was analyzed by a commercial laboratory according to standard methods (EKO-LAB Ž amberk s. r. o., Ž amberk, Czech Republic). After the container substrate was examined for signs of fungal colonization it was rinsed from roots under a stream of tap water. Five 50 cm 3 subsamples of roots were taken, composited into one sample per plant, and processed for evaluation of ErM and DSE colonization. The remaining roots were oven-dried for 3 h at 90°C and weighed. Subsamples taken for evaluation of colonization comprised a negligible portion of total root volume and were excluded from the final measure of root biomass. Additionally, we calculated shoot:root biomass ratio and N:P ratio. ErM and DSE colonization was assessed blindly on a cell-by-cell basis at 400 and 1,000× magnification using an Olympus BX60 light microscope equipped with DIC by a single experienced person (T. L.). An average of 1010 rhizodermal and cortical cells was evaluated per plant. Statistical analysis was performed with STATISTICA 9.1 (StatSoft, Inc., Tulsa, USA). ANOVA assumptions were assessed by Levene ’ s test for homogeneity of variances and Chi-square test for normal distribution. Dependent variables were log-transformed as needed to meet ANOVA assumptions and subjected to two-way ANOVA (variables assessed on destructively harvested plants) or repeated two-way ANOVA (shoot growth over time). Tukey ’ s HSD test was used for post-hoc mean comparisons. Dependent variables that violated ANOVA assumptions even when transformed (shoot: root ratio) were analyzed by Kruskal-Wallis ANOVA. Statistical significance was p <0.05 for all analyses. In 2007, one plant inoculated with PFO-F yielded 3 fruits, two plants inoculated with AER-1 together yielded 6 fruits, two plants inoculated with AER-1 + RER-1 yielded together seven fruits, and three plants inoculated with AER-1 + OMA-B together yielded 15 fruits. The remaining plants did not fruit and no fruiting occurred in 2008. Although the positive effect of AER-1 on precocious fruit bearing is apparent, the difference in yield among treatments was not tested statistically due to the low number of fruits. The cultivation substrate inoculated with AER-1 was colonized by a dense whitish mycelium that occasion- ally formed hyphal strands. The mycelium grew in the rhizosphere around old and young roots without any apparent negative interaction (Fig. 1). This mycelial growth was characteristic of the growth pattern of AER-1 on low nutrient media and mycelium of a similar appearance was not observed in non-AER1-inoculated treatments. Therefore, we considered this substrate colonization as formed by A. praecox AER-1. Shoot growth was affected by SAP, SYM, time, and SAP × time and SYM × time interactions while the remaining interaction terms were not significant (Table 2). Post-hoc comparisons of SAP and SYM effects on shoot length were therefore considered at each of the three measurement dates. Shoot growth benefited from AER- 1 already after 3 months and this effect increased as the experiment progressed (Fig. 2). SYM treatments differed significantly in their effects on shoot growth at 3 and 14 months but not after 30 months, but the effects were less pronounced than those of SAP (Fig. 3). OMA-B increased shoot growth compared to PFO-F at 3 and 14 months, while RER-1 increased shoot growth compared to PFO-F at 14 months only (Fig. 3). However, shoot growth of plants inoculated with OMA-B, PFO-F, or RER-1 did not differ from those without SYM inoculum at any point in the experiment (Fig. 3). After 30 months, a positive effect of SAP on total shoot, root and total dry weight was highly significant but there was no significant effect of SYM or SAP × SYM interaction (Table 2). The shoot:root ratio was not affected by inoculation with SAP, SYM, or their interaction (data not shown). The leaf K and Ca concentrations were not affected by the two types of inoculation or their interaction, while SAP and SYM interacted to affect Mg (Table 3). Where AER-1 was not present, leaf Mg increased with OMA-B and RER-1 in comparison to PFO-F but each of these did not differ from the non-inoculated control (Table 3). Leaf N concentration was affected by SYM and the SAP × SYM interaction. Among plants without AER-1, OMA-B significantly decreased foliar N concentration vs. PFO-F, RER-1, or none (Table 3). Leaf P differed among SYM treatments but was not affected by SAP or SAP × SYM interaction (Table 3). Across SAP treatments, PFO-F increased leaf P concentration by 0.014% compared to OMA-B and RER-1 but these did not differ from the non-inoculated control (data not shown). The N:P ratio was not affected by SYM but was affected by SAP and the SYM × SAP interaction (Table 3). When AER-1 was added, RER-1 increased leaf N:P relative to PFO-F, while OMA-B and none did not differ from RER-1 or PFO-F. Where AER-1 was not added, OMA-B decreased leaf N:P relative to none, while leaf N:P in PFO-F and RER-1 treatments did not differ from OMB-B or none (Table 3). At plant harvest, leaf N was deficient (<1.7%) across treatments while P concentrations (> 0.10%) were adequate (Hanson and Hancock 1996). Because root colonization by DSE was very low (mean <1% across treatments) and not affected by inoculation with P. fortinii PFO-F, both ErM and DSE colonization were combined into a single pa- rameter, total fungal colonization. The effect of SAP, SYM or SAP × SYM interaction on total fungal colonization was not significant ( H 0 12.64, p 0 0.08); however, non-inoculated plants and plants inoculated with AER-1 tended to have the lowest (48%±14%; mean ± 95% confidence interval) and highest (64%±2%) mean colonization, respectively. The applicability of the classical N-mineralization model, in which plants depend on mineralization of nutrients by free-living microbes, to ecosystems comprised of ecto- and ericoid mycorrhizal plants was called into question by Lindahl et al. (2002), who argued against the accrual of readily available nutrients in the soil solution and emphasized instead that fungal mycelium, including that of mycorrhizal fungi, is the primary agent of nutrient storage and transfer in forested ecosystems. Stratification of saprotrophic and mycorrhizal fungi among upper and lower horizons of forest soils corresponds closely to the decomposition state and nutrient content of organic matter in each horizon (Lindahl et al. 2007). In these soils, litter-decomposing fungi specialize in breakdown of complex C in recent plant litter deposits while mycorrhizal fungi specialize in acquisition of plant nutrients from organic matter too depleted in C to support purely saprotrophic microbes (Hobbie and Horton 2007). However, spatial separation of both fungal groups is not strict and these may physically interact, with significant consequences to plants. Net positive transfer of P to the ectomycorrhizal (EcM) fungal mycelium during physical interaction between the fungal saprotroph Hypholoma fasciculare (Fr.) Kumm. and the EcM Suillus variegatus (Fr.) O. Kuntze and Paxillus involutus (Fr.) Fr. ultimately increased P-capture by the EcM host plant P. sylvestris (Lindahl et al. 1999). Pinus contorta Dougl. ex Loudon biomass increased with introduction of the saprotrophic basidiomycete Mycena galopus (Pers.) P. Kumm in axenic mesocosms containing protein (hide powder) or chitin as N ...
Citations
... Besides providing baseline data for future studies, our results could be potentially exploited during designing plant bio-stimulants aimed to enhance the growth of native species during restoration efforts. While inoculations of economically important ericaceous crops (especially Vaccinium spp.) traditionally rely on the ErMF (Scagel 2005), some studies show that alternative scenarios might be more efficient (Vohník et al. 2012) and we suggest that future studies consider the root-symbiotic bacteria, either alone or in combination with local symbiotic fungi. 3,2 ± 0,2 1.5 ± 1.2 GC14 ----+ -30.9 ± 23.9 4,0 ± 0,9 -GC22 ------58.1 ± 1.2 2,7 ± 0,6 -GC31 ----+ 1.9 ± 0.0 83.7 ± 0.8 3,7 ± 3,6 1.9 ± 0.0 GC47 ---224.1 ± 8.6 + 2.2 ± 0.1 55.2 ± 0.7 2,3 ± 0,4 2.2 ± 0.1 GC51 ---204.6 ± 7.3 -2.4 ± 0.2 70.0 ± 0.3 0,2 ± 0,0 2.4 ± 0.2 GC55 ---198.4 ...
Ericaceous plants (Ericaceae, the heath family) establish complex symbioses with soil-borne microorganisms that facilitate their survival in challenging environments such as nutrient-impoverished heathlands, heavy metal-polluted soils, and inert volcanic rock substrates. While the symbiosis with the ericoid mycorrhizal (ErM) fungi has attracted significant attention, little is known about the endophytic bacteria and how they affect fitness of their ericaceous hosts. In this study, we isolated and identified endophytic bacteria from hair roots of Gaultheria poeppigii colonizing volcanic deposits at a site in the Chilean southern Andes. In addition, their in vitro capacity to solubilize phosphate, produce exopolysaccharides, siderophores, ammonia, indole acetic acid (IAA), and 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity was evaluated. In total, 74 isolates were obtained, belonging to the phyla Proteobacteria, Firmicutes, and Actinobacteria and the genera Paraburkholderia, Paenibacillus, Variovorax, Bacillus, Leifsonia, and Arthrobacter. Only two Paraburkholderia sp. isolates showed phosphate solubilization. Siderophore production was detected in six isolates, with the highest production detected in the Variovorax paradoxus. All strains produced ammonia and IAA in different amounts and six displayed ACC deaminase activity, the highest being detected in V. paradoxus GC55. The results of our biocontrol assay showed that V. paradoxus GC51 had the highest percentages of inhibition of common phytopathogens with values ranging from 65 to 100%. To our best knowledge, this is the first report on the cultivable bacteria colonizing the hair roots of ericaceous plants growing in volcanic deposits and our results suggest that at least some of them might promote the host growth and confer protection against pathogens. We suggest that not only the ErM fungi but also the root-symbiotic bacteria contribute to the remarkable resilience of ericaceous plants in challenging environments such as volcanic deposits.
... Appreciation of the diversity of putative ErM colonizing Ericaceae roots has expanded recently (Bougoure et al. 2007;Fehrer et al. 2019) to include many ascomycetes in the order Helotiales (Walker et al. 2011) and some basidiomycetes (Selosse et al. 2007;Vohník et al. 2012). A recent study of ErM diversity in Norwegian heathlands found several new ErM operational taxonomic units (OTUs) within both Ascomycota and Basidiomycota associating with heather roots (Blaalid & Davey 2022). ...
Atmospheric pollution containing soil‐nitrifying ammonium sulfate ((NH₄)₂SO₄) affects semi‐natural ecosystems worldwide. Long‐term additions of (NH₄)₂SO₄ to nitrogen (N)‐limited habitats, including heathlands, increase climate stress affecting recovery from wildfires. Although heathland vegetation largely depends on ericoid mycorrhizal fungi (ErM) to access soil N, we lack detailed understanding of how prolonged exposure to (NH₄)₂SO₄ may alter ErM community composition and host plants' reliance on fungal partners following wildfire and affect recovery. Simulation of atmospheric pollution ((NH₄)₂SO₄) occurred bi‐weekly for 5 years after a 2006 wildfire in a UK heathland. Ten years after treatments ceased, we measured vegetation structure, lichen and lichen photobiont composition, soil characteristics, ErM colonization, ErM diversity in roots and soil, and assessed ErM potential as novel recovery indicators. Heather height and density, and moss groundcover, were greater in N‐enriched plots. Lichen community indices showed significant treatment effects, but without differences in photobionts. Soil pH and Mg were significantly lower in treated plots while soil cation exchange capacity was significantly higher. There were no detectable differences in ErM composition and keystone ErM taxa between control and treated plots. Soil carbon stock measures were variable. Our results indicate atmospheric pollution following fire can have significant lingering effects above‐ and belowground. ErM diversity and root colonization were not assessed in the original N‐addition experiment; we advocate for their inclusion in future studies as an integral part of the recovery assessment toolkit. We show that mycorrhizal fungi diversity is a viable ecological tool and summarize key steps for ErM identification.
... Although part of the relationship between vegetation composition and soil C pool can be explained based on plant traits (De Deyn et al. 2008, Rossi et al. 2020, it is becoming clear that symbiotic fungi and their interaction with free-living fungi also play an important role in this relationship. Fungi with the ability to form ErM are known for their substantial saprotrophic capabilities (Martino et al. 2018), some species can even decompose highly recalcitrant substrates, such as lignin (Vohník et al. 2012). The mycelia of some EcM and ErM fungi have melanized hyphae resistant to decomposition, which has been proposed to play a central role in soil C sequestration Koide 2014, Clemmensen et al. 2015). ...
... While the Gadgil effect can be particularly strong on sites where saprotrophs compete with EcM fungi (Kyaschenko et al. 2017), it has been recently shown by Fanin et al. (2022) that dwarf shrubs and associated ErM fungi impaired decomposition and nutrient cycling, suggesting a Gadgil effect caused by ericoid shrubs and their fungal partners. Considering the extracellular enzymatic activity of ErM fungi (Read et al. 2004, Vohník et al. 2012) as well as high gene contents for polysaccharide-degrading enzymes, lipases, and proteases (Martino et al. 2018), ErM fungi may compete with saprotrophs for N in organic soil (Fanin et al. 2022, Mielke et al. 2022 or act as sufficient saprotrophs by themselves. In this context, it remains unclear whether the observed relationship between soil C content and fungal community composition is driven by the production of more recalcitrant necromass of endophytic fungi or because fungi associated with ericoid dwarf shrubs can contribute to nutrient limitation, impairing saprotroph decomposition and leading to an accumulation of organic matter as in boreal forest ecosystem. ...
Alpine tundra ecosystems suffer from ongoing warming-induced tree encroachment and vegetation shifts. While the effects of tree line expansion on the alpine ecosystem receive a lot of attention, there is also an urgent need for understanding the effect of climate change on shifts within alpine vegetation itself, and how these shifts will consequently affect soil microorganisms and related ecosystem characteristics such as carbon storage. For this purpose, we explored relationships between climate, soil chemistry, vegetation, and fungal communities across seven mountain ranges at 16 alpine tundra locations in Europe. Among environmental factors, our data highlighted that plant community composition had the most important influence on variation in fungal community composition when considered in combination with other factors, while climatic factors had the most important influence solely. According to our results, we suggest that rising temperature, associated with a replacement of ericoid-dominated alpine vegetation by non-mycorrhizal or arbuscular mycorrhizal herbs and grasses, will induce profound changes in fungal communities towards higher dominance of saprotrophic and arbuscular mycorrhizal fungi at the expense of fungal root endophytes. Consequently, topsoil fungal biomass and carbon content will decrease.
... Except confirmed and probable ErMF, ericaceous plants associate with a plethora of root mycobionts with unknown symbiotic status, including typical ectomycorrhizal (EcM) and saprobic basidiomycetes (e.g., Allen et al. 2003;Bougoure et al. 2007;Walker et al. 2011;Grelet et al. 2017). Under artificial conditions, these may form intracellular hyphal loops or pegs in the rhizodermal cells of ericaceous plants (e.g., Walker et al. 2011;Villarreal-Ruiz et al. 2012;Vohník et al. 2012a;Grelet et al. 2017) and even support the growth of the inoculated plants (Vohník et al. 2012b;Grelet et al. 2017), but the eco-physiological significance of such observations remains unclear. The mechanisms behind these positive effects are unknown and may include a release of nutrients to the host´s rhizosphere through autolysis of their mycelium (Duclos et al. 1983) and mineralization of organically bound nutrients (Vohník et al. 2012b;Grelet et al. 2017). ...
... Under artificial conditions, these may form intracellular hyphal loops or pegs in the rhizodermal cells of ericaceous plants (e.g., Walker et al. 2011;Villarreal-Ruiz et al. 2012;Vohník et al. 2012a;Grelet et al. 2017) and even support the growth of the inoculated plants (Vohník et al. 2012b;Grelet et al. 2017), but the eco-physiological significance of such observations remains unclear. The mechanisms behind these positive effects are unknown and may include a release of nutrients to the host´s rhizosphere through autolysis of their mycelium (Duclos et al. 1983) and mineralization of organically bound nutrients (Vohník et al. 2012b;Grelet et al. 2017). In addition, ericaceous plants often associate with the so-called dark septate endophytes (DSE), a miscellaneous group of ascomycetous mycobionts with melanized hyphae that are ubiquitous in the roots of boreal and temperate plants and whose effects range from positive to negative (Newsham 2011;Mayerhofer et al. 2013). ...
... However, under certain scenarios, they can be beneficial for the growth of ericaceous plants even without forming a root-fungus symbiosis (Vohník 2020). For example, under natural conditions they never interact with fungus-free roots and there is an indication that they might benefit ericaceous plants through interactions with ErMF (Vohník et al. 2012b). More experimental work is apparently needed to resolve this issue, ideally employing a combined inoculum containing both ErMF and asymbiotic saprobic fungi. ...
Most of our knowledge on the ericoid mycorrhizal (ErM) symbiosis comes from temperate heathlands characterized by acidic peaty soils and many experiments with a few ascomycetous fungi. However, ericaceous plants thrive in many other ecosystems and in temperate coniferous forests, their seedlings often prosper on decomposing wood. While wood is typically exploited by basidiomycetous ectomycorrhizal (EcM) and saprobic fungi, the role of ErM fungi (ErMF) is much less clear. We explored the cultivable mycobiota of surface sterilized hair roots of Vaccinium spp. growing on decomposing wood in two coniferous forests in Mid-Norway (Scandinavia) and Northern Bohemia (Central Europe). Obtained isolates were identified using molecular tools and their symbiotic potential was tested in vitro. While the detected community lacked the archetypal ErMF Hyaloscypha hepaticicola and the incidence of dark septate endophytes and EcM fungi was negligible, it comprised other frequent asexual ascomycetous ErMF, namely H. variabilis and Oidiodendron maius, together with several isolates displaying affinities to sexual saprobic H. daedaleae and H. fuckelii. Ascomycete-suppressing media revealed representatives of the saprobic basidiomycetous genera Coprinellus, Gymnopilus, Mycena (Agaricales), and Hypochnicium (Polyporales). In the resyntheses, the tested basidiomycetes occasionally penetrated the rhizodermal cells of their hosts but never formed ericoid mycorrhizae and in many cases overgrew and killed the inoculated seedlings. In contrast, a representative of the H. daedaleae/H. fuckelii-related isolates repeatedly formed what morphologically appears as the ErM symbiosis and supported host's growth. In conclusion, while basidiomycetous saprobic fungi have a potential to colonize healthy-looking ericaceous hair roots, the mode(-s) of their functioning remain obscure. For the first time, a lineage in Hyaloscypha s. str. (corresponding to the former Hymenoscyphus ericae aggregate) where sexual saprobes are intermingled with root symbionts has been revealed, shedding new light on the ecology and evolution of these prominent ascomycetous ErMF.
... Except con rmed and probable ErMF, ericaceous plants associate with a plethora of root mycobionts with unknown symbiotic status, including typical ectomycorrhizal (EcM) and saprobic basidiomycetes (e.g., (Allen et al. 2003;Bougoure et al. 2007;Walker et al. 2011;Grelet et al. 2017). Under arti cial conditions, these may form intracellular hyphal loops or pegs in the rhizodermal cells of ericaceous plants (e.g., (Walker et al. 2011;Villarreal-Ruiz et al. 2012;Vohník et al. 2012a;Grelet et al. 2017) and even support the growth of the inoculated plants (Vohník et al. 2012b;Grelet et al. 2017), but the eco-physiological signi cance of such observations remains unclear. The mechanisms behind these positive effects are unknown and may include a release of nutrients to the host´s rhizosphere through autolysis of their mycelium (Duclos et al. 1983) and mineralization of organically bound nutrients (Vohník et al. 2012b;Grelet et al. 2017). ...
... Under arti cial conditions, these may form intracellular hyphal loops or pegs in the rhizodermal cells of ericaceous plants (e.g., (Walker et al. 2011;Villarreal-Ruiz et al. 2012;Vohník et al. 2012a;Grelet et al. 2017) and even support the growth of the inoculated plants (Vohník et al. 2012b;Grelet et al. 2017), but the eco-physiological signi cance of such observations remains unclear. The mechanisms behind these positive effects are unknown and may include a release of nutrients to the host´s rhizosphere through autolysis of their mycelium (Duclos et al. 1983) and mineralization of organically bound nutrients (Vohník et al. 2012b;Grelet et al. 2017). In addition, ericaceous plants often associate with the so-called dark septate endophytes (DSE), a miscellaneous group of ascomycetous mycobionts with melanized hyphae that are ubiquitous in the roots of boreal and temperate plants and whose effects on host plants range from positive to negative (Newsham 2011;Mayerhofer et al. 2013). ...
... However, under certain scenarios, they can be bene cial for the growth of ericaceous plants even without forming a root-fungus symbiosis (Vohník 2020). For example, under natural conditions they never interact with fungus-free roots and there is an indication that they might bene t ericaceous plants through interactions with ErMF (Vohník et al. 2012b). More experimental work is apparently needed to resolve this issue, ideally employing a combined inoculum containing both ErM and asymbiotic saprobic fungi. ...
Most of our knowledge on the ericoid mycorrhizal (ErM) symbiosis comes from temperate heathlands characterized by acidic peaty soils and many experiments with a few ascomycetous fungi. However, ericaceous plants thrive in many other habitats and in temperate coniferous forests, their seedlings often prosper on decomposing wood. While wood is typically exploited by basidiomycetous ectomycorrhizal (EcM) and saprobic fungi, the role of ErM fungi (ErMF) is much less clear. We explored the cultivable mycobiota of surface sterilized hair roots of Vaccinium spp. growing on decomposing wood in two coniferous forests in Northern Bohemia and Mid-Norway. Obtained isolates were identified using molecular tools and their symbiotic potential was tested in vitro . While the detected community lacked the archetypal ErMF Hyaloscypha hepaticicola and the incidence of dark septate endophytes and EcM fungi was negligible, it comprised other frequent asexual ascomycetous ErMF, namely H. variabilis and Oidiodendron maius , together with several isolates displaying affinities to sexual saprobic H. daedaleae and H. fuckelii . Ascomycete-suppressing media revealed representatives of the saprobic basidiomycetous genera Coprinellus , Gymnopilus , Mycena (Agaricales) and Hypochnicium (Polyporales). In the resyntheses, the tested basidiomycetes occasionally penetrated rhizodermal cells of their hosts but never formed ericoid mycorrhizae and in many cases overgrew and killed the inoculated seedlings. In contrast, a representative of the H. daedaleae / H. fuckelii -related isolates repeatedly formed what morphologically appears as the ErM symbiosis and supported host´s growth. In conclusion, while basidiomycetous saprobic fungi have a potential to colonize healthy-looking ericaceous hair roots, the mode(-s) of their functioning remain obscure. For the first time, a lineage in Hyaloscypha s. str. (formerly the Hymenoscyphus ericae aggregate) where sexual saprobes are intermingled with root symbionts has been revealed, shedding new light on the ecology and evolution of these prominent ascomycetous ErMF.
... Although no ErM fungi have been identified in this genus, research has shown that ectomycorrhizal fungi can also colonize Ericaceae roots (Villarreal-Ruiz et al., 2004, 2012Vrålstad, 2004). Furthermore, saprotrophic fungi can help degrade plant debris and extract nitrogen and phosphorus from lignocellulose more efficiently than mycorrhizal fungi and can, therefore, be beneficial for plant growth (Vohník et al., 2012). Finally, the Sebacinales order mainly composed of Serendipita sp. ...
Thermal pruning was a common pruning method in the past but has progressively been replaced by mechanical pruning for economic reasons. Both practices are known to enhance and maintain high yields; however, thermal pruning was documented to have an additional sanitation effect by reducing weeds and fungal diseases outbreaks. Nevertheless, there is no clear consensus on the optimal fire intensity required to observe these outcomes. Furthermore, fire is known to alter the soil microbiome as it impacts the soil organic layer and chemistry. Thus far, no study has investigated into the effect of thermal pruning intensity on the wild blueberry microbiome in agricultural settings. This project aimed to document the effects of four gradual thermal pruning intensities on the wild blueberry performance, weeds, diseases, as well as the rhizosphere fungal and bacterial communities. A field trial was conducted using a block design where agronomic variables were documented throughout the 2-year growing period. MiSeq amplicon sequencing was used to determine the diversity as well as the structure of the bacterial and fungal communities. Overall, yield, fruit ripeness, and several other agronomical variables were not significantly impacted by the burning treatments. Soil phosphorus was the only parameter with a significant albeit temporary change (1 month after thermal pruning) for soil chemistry. Our results also showed that bacterial and fungal communities did not significantly change between burning treatments. The fungal community was dominated by ericoid mycorrhizal fungi, while the bacterial community was mainly composed of Acidobacteriales, Isosphaerales, Frankiales, and Rhizobiales. However, burning at high intensities temporarily reduced Septoria leaf spot disease in the season following thermal pruning. According to our study, thermal pruning has a limited short-term influence on the wild blueberry ecosystem but may have a potential impact on pests (notably Septoria infection), which should be explored in future studies to determine the burning frequency necessary to control this disease.
... For instance, several studies have highlighted the importance of ligninolytic EcM fungal taxa that have retained class II peroxidases from white-rot saprotrophs (B€ odeker et al., 2009Lindahl et al., 2021;Argiroff et al., 2022). Although ascomycetous ErM fungi possess enzymes involved in the degradation of a wide variety of recalcitrant plant substrates, including lignin (Haselwandter et al., 1990;, 2002Wurzburger et al., 2012;Miyauchi et al., 2020), they do not possess the enzymes needed to completely mineralize lignin C as is the case for white-rot fungi Vohn ık et al., 2012b). In this instance, particular ligninolytic EcM fungi might enhance organic matter losses, whereas ascomycetous ErM fungi might contribute to its accumulation Lindahl et al., 2021). ...
Ericoid mycorrhizal (ErM) shrubs commonly occur in forest understories and could therefore alter arbuscular (AM) and/or ectomycorrhizal (EcM) tree effects on soil carbon and nitrogen dynamics. Specifically, ErM fungi have extensive organic matter decay capabilities, and ErM plant and fungal tissues have high concentrations of secondary compounds that can form persistent complexes in the soil. Together, these traits could contribute to organic matter accumulation and inorganic nutrient limitation. These effects could also differ in AM‐ vs EcM‐dominated stands at multiple scales within and among forest biomes by, for instance, altering fungal guild interactions. Most work on ErM effects in forests has been conducted in boreal forests dominated by EcM trees. However, ErM plants occur in c. 96, 69 and 29% of boreal, temperate and tropical forests, respectively. Within tropical montane forests, the effects of ErM plants could be particularly pronounced because their traits are more distinct from AM than EcM trees. Because ErM fungi can function as free‐living saprotrophs, they could also be more resilient to forest disturbances than obligate symbionts. Further consideration of ErM effects within and among forest biomes could improve our understanding of how cooccurring mycorrhizal types interact to collectively affect soil carbon and nitrogen dynamics under changing conditions.
... Inoculation of blueberry with the endophytic fungus Anteaglonium improved root growth and shoot branching, which may be largely attributed to phytohormone signalling and biosynthesis in inoculated plants (Wu et al. 2021). Contrary to our results, Vohník et al. (2012) did not observe a biomass increase in V. corymbosum inoculated with the root symbiotic fungi: O. maius, H. ericae and P. fortinii. However, the addition of Agrocybe praecox, a saprotrophic basidiomycete, positively affected plant growth and biomass production. ...
... However, the addition of Agrocybe praecox, a saprotrophic basidiomycete, positively affected plant growth and biomass production. This effect may be associated with improved nutrient release from plant residues in the substrate by the lignin-degrading fungus (Vohník et al. 2012). ...
Ecological methods are becoming increasingly popular. One of these methods is plant biotization. In our paper, we focus on selection of Vaccinium corymbosum hairy root-inhabiting fungi for plant growth promotion in a single microorganism inoculation setup and then composed a multiorganismal inoculum enriched with a representative of another group of fungi, leaf endophytes. The hairy roots of V. corymbosum hosted 13 fungal taxa. In single inoculation of the plant with fungal strains, the most beneficial for plant growth were Oidiodendron maius and Phialocephala fortinii. Additional inoculation of the plants with three root symbiotic fungi (O. maius, Hymenoscyphus sp. and P. fortinii) and with the endophytic fungus Xylaria sp. increased plant height in laboratory experiments. On a semi-industrial scale, inoculation improved plant biomass and vitality. Therefore, the amendment of root-associated fungal communities with a mixture of ericoid mycorrhizal and endophytic fungi may represent an alternative to conventional fertilization and pesticide application in large-scale blueberry production.
Key points
• O. maius and P. fortinii significantly stimulated V. corymbosum growth in a single inoculation.
• Multimicroorganismal inoculum increased plant biomass and vitality.
• Blueberry biotization with ericoid and endophytic fungi is recommended.
Graphical abstract
... Recent insights into DSE genetics revealed that DSEs hold a remarkably high proportion of saprophytic genes in their genomes (Knapp et al., 2018;Schlegel et al., 2016). DSEs produce a broad range of hydrolytic and oxidative enzymes, including amylases, cellulases, laccases, lipases, pectinases, polyphenol oxidases, proteolytic enzymes, and xylanases, and show incomplete ligninolytic activity (Caldwell et al., 2000;Surono and Narisawa, 2017;Vohník et al., 2012). They support their host via the mineralization of a complex soil substrate, thereby releasing nutrients that plants can easily absorb (Ruotsalainen et al., 2021;Vohník et al., 2012). ...
... DSEs produce a broad range of hydrolytic and oxidative enzymes, including amylases, cellulases, laccases, lipases, pectinases, polyphenol oxidases, proteolytic enzymes, and xylanases, and show incomplete ligninolytic activity (Caldwell et al., 2000;Surono and Narisawa, 2017;Vohník et al., 2012). They support their host via the mineralization of a complex soil substrate, thereby releasing nutrients that plants can easily absorb (Ruotsalainen et al., 2021;Vohník et al., 2012). It is hypothesized that in return, DSEs require only a minor investment of plant resources because being saprophytes, they might obtain carbon (C) from plant metabolic waste by-products (Ruotsalainen et al., 2021) (Fig. 1). ...
Dark septate endophytes (DSEs) comprise a diverse and ubiquitous group of fungal generalists with broad habitat niches that robustly colonize the roots of plants in stressful environments. DSEs possess adaptation strategies that determine their high tolerance to heavy metal (HM) contamination, drought, and salinity. Most DSEs developed efficient melanin-dependent and melanin-independent mechanisms of HM detoxification and osmoprotection, including intracellular immobilization and extracellular efflux of HMs and excess ions, and the scavenging of reactive oxygen species. DSEs form mutualistic relationship with plants according to the hypothesis of “habitat-adapted associations”, supporting the survival of their hosts under stressful conditions. As saprophytes, DSEs mineralize a complex soil substrate improving plants’ nutrition and physiological parameters. They can protect the host plant from HMs by limiting HM accumulation in plant tissues and causing their sequestration in root cell walls as insoluble compounds, preventing further HM translocation to shoots. The presence of DSE in drought-affected plants can substantially ameliorate the physiology and architecture of root systems, improving their hydraulic properties. Plant growth-promoting features, supported by the versatility and easy culturing of DSEs, determine their high potential to enhance phytoremediation and revegetation projects for HM-contaminated, saline, and desertic lands reclamation.
... On the other hand, considering the limitations of resynthesis experiments with core Ericaceae and their root mycobionts (Leake and Read 1991;Vohník 2020), the results obtained here suggest that they are at least harmless symbionts of ericaceous plants. The observed positive effects on the growth of their hosts may be realized through the ErM symbiosis, various indirect/non-symbiotic effects such as substrate mineralization, mitigation of substrate toxicity, etc. (e.g., Gorman and Starrett 2003;Vohník et al. 2012) or a combination of both. ...
Historically, Hyaloscypha s. lat. (Hyaloscyphaceae, Helotiales) included various saprobes with small apothecia formed on decaying plant matter, usually wood, that were defined by chemical and (ultra)structural aspects. However, recent molecular phylogenetic and resynthesis studies have narrowed the concept of the genus and shown that it contains several widely distributed species with unknown sexual morphs that form ectomycorrhizae, ericoid mycorrhizae, and mycothalli and also grow endophytically in plant roots and hypogeous ectomycorrhizal (EcM) fruitbodies (i.e., the historical Hymenoscyphus ericae aggregate). Hence, some of the sexually reproducing saprobic Hyaloscypha s. lat. and the symbionts belong to the monophyletic Hyaloscypha s. str. Here, we introduce two new root-symbiotic Hyaloscypha s. str. species, i.e., H. gabretae and H. gryndleri spp. nov. While the former was isolated only from ericaceous hosts (Vaccinium myrtillus from Southern Bohemia, Czechia and Calluna vulgaris from England, UK), the latter was obtained from a basidiomycetous EcM root tip of Picea abies (Pinaceae), roots of Pseudorchis albida (Orchidaceae), and hair roots of V. myrtillus from Southern Bohemia and C. vulgaris from England. Hyaloscypha gryndleri comprises two closely related lineages, suggesting ongoing speciation, possibly connected with the root-symbiotic life-style. Fungal isolates from ericaceous roots with sequences similar to H. gabretae and H. gryndleri have been obtained in Japan and in Canada and Norway, respectively, suggesting a wide and scattered distribution across the Northern Hemisphere. In a series of in vitro experiments, both new species failed to form orchid mycorrhizal structures in roots of P. albida and H. gryndleri repeatedly formed what morphologically corresponds to the ericoid mycorrhizal (ErM) symbiosis in hair roots of V. myrtillus, whereas the ErM potential of H. gabretae remained unresolved. Our results highlight the symbiotic plasticity of root-associated hyaloscyphoid mycobionts as well as our limited knowledge of their diversity and distribution, warranting further ecophysiological and taxonomic research of these important and widespread fungi.
