Suillus Luteus Research Articles

Effects of ECMF Isolated from Mining Areas on Water Status, Photosynthesis Capacity, and Lead Ion Transport of Populus alba Under Pb Stress

Native ectomycorrhizal fungi (ECMF) are generally more effective than non-native ECMF in facilitating the phytoremediation of heavy metal (HM) ions from contaminated soils. This study aimed to investigate the contributions of four ECMF species—Suillus luteus, Suillus flavidus, Suillus variegatus, and Gomphidius glutinosus—that were isolated from mining areas to the growth, water status, photosynthesis, and metallothionein gene expression of Populus alba exposed to varying concentrations of lead (Pb). The experiment lasted two months and involved P. alba cuttings subjected to Pb concentrations of 0, 200, and 400 mg kg−1, representing no Pb stress, moderate Pb stress, and severe Pb stress, respectively. Results indicated that S. flavidus significantly enhanced the growth, water status, photosynthesis parameters, and metallothionein gene expression of P. alba under Pb stress, whereas S. luteus only exhibited positive effects under severe Pb stress. S. variegatus negatively affected the growth, water status, photosynthesis, and metallothionein gene expression of P. alba under Pb stress, while no significant difference was observed between the control treatment and G. glutinosus symbiosis. Therefore, S. flavidus and S. luteus are promising ECMF species for ecological restoration in mining areas, especially in P. alba woodlands.

Light Drought Stress Positively Influenced Root Morphological and Endogenous Hormones in Pinus massoniana Seedlings Inoculated with Suillus luteus

Aims An ectomycorrhizal fungus (ECMF) may enhance plant drought resistance. However, there is limited information regarding the effects of ECMFs on drought resistance in Pinus massoniana Lamb., a native species representing an afforestation pioneer tree in subtropical regions of China. Methods In this study, a pot experiment was conducted to determine the effects of ECMF Suillus luteus inoculation on the root morphology and endogenous hormones of P. massoniana, including roots, leaves, and stems, under various water treatment conditions. Four water levels (regular, light, moderate, and severe drought) and three inoculations (inoculated Suillus luteus, numbered S12 and S13, and non-ECMF-inoculated) were compared using a factorial design. Results Under drought stress, P. massoniana seedlings inoculated with S12 and S13 had significantly increased root morphology development (p < 0.05). Light drought positively influenced root development, resulting in a more than twofold increase in root length and root surface area compared to non-inoculated seedlings. Concentrations of gibberellic acid (GA), zeatin riboside (ZR), and indole-3-acetic acid (IAA) in roots, stems, and leaves of inoculated S12 and S13 plants were elevated, whereas abscisic acid (ABA) concentrations were significantly lower, compared to non-inoculated seedlings. The ABA concentrations in the roots of S12 and S13 inoculated seedlings under light drought stress were 1.5 times lower than those in non-inoculated controls. Moreover, root development was positively correlated with plant total GA, IAA, and ZR but negatively correlated with ABA. ConclusionsS. luteus can promote the root growth and development of P. massoniana seedlings, notably by regulating the balance in the concentration of endogenous hormones, thus improving the drought resistance of P. massoniana seedlings.

Structural characterization of an acid-extracted polysaccharide from Suillus luteus and the regulatory effects on intestinal flora metabolism in tumor-bearing mice

Suillus luteus is an excellent edible fungus that has been applied in soil remediation and environmental pollution control, while the development of bioactive polysaccharide component including structural performance and intestinal flora regulation is still insufficient. In this study, a S. luteus acid-extracted polysaccharide (SLAP) was prepared under room temperature, then the structural characteristics and regulatory effects on gut microbiota metabolism in tumor-bearing mice were investigated. Results showed that SLAP was a kind of gulcomannan (average molecular weight of 1.76 × 107 Da) comprised of Xyl, Man, Glc, Gal (molar ratio of 0.19:1.00:0.72:0.53), which took β-(1 → 4)-Manp and β-(1 → 4)-Glcp as the backbone with β-(1 → 6)-Glcp and α-(1 → 6)-Galp as branches. The animal experiment results demonstrated that SLAP could effectively enhance the immunoregulatory activities of CD4+ and CD8+ T cells in tumor-bearing mice via improving intestinal lactobacillaceae contents and promoting primary bile acids biosynthesis, finally leading to the suppression of solid tumors growth with an inhibitory rate of 61.14 % (100 mg/kg·d). These results would provide certain data support and research basis for further applications of SLAP as an immunomodulatory adjuvant in food and medicine fields.

Differential Strategies of Ectomycorrhizal Development between Suillus luteus and Pinus massoniana in Response to Nutrient Changes.

Ectomycorrhizal fungi employ different strategies for mycelial growth and host colonization under varying nutrient conditions. However, key genes associated with mycorrhizal interaction should be influenced solely by the inoculation treatment and not by nutrient variations. To utilize subtle nutrient differences and rapidly screen for key genes related to the interaction between Suillus luteus and Pinus massoniana, we performed an inoculation experiment using culture bottles containing high- and low-nutrient media. Interestingly, S. luteus LS88 promoted the growth of P. massoniana seedlings without mature ectomycorrhiza, and the impact of LS88 inoculation on P. massoniana roots was greater than that of nutrient changes. In this study, the resequenced genome of the LS88 strain was utilized for transcriptome analysis of the strain. The analysis indicated that a unique gene encoding glutathione S-transferase (GST) in LS88 is likely involved in colonizing P. massoniana roots. In this study, the GST gene expression was independent of nutrient levels. It was probably induced by P. massoniana and could be used as a marker for S. luteus colonization degree.

Molecular characterization of a novel mitovirus from the plant-pathogenic fungus Nigrospora oryzae.

Here, we characterized a novel mitovirus from the fungus Nigrospora oryzae, which was named "Nigrospora oryzae mitovirus 3" (NoMV3). The NoMV3 genome is 2,492 nt in length with a G + C content of 33%, containing a single large open reading frame (ORF) using the fungal mitochondrial genetic code. The ORF encodes an RNA-dependent RNA polymerase (RdRp) of 775 amino acids with a molecular mass of 88.75 kDa. BLASTp analysis revealed that the RdRp of NoMV3 had 68.6%, 50.6%, and 48.6% sequence identity to those of Nigrospora oryzae mitovirus 2, Suillus luteus mitovirus 6, and Fusarium proliferatum mitovirus 3, respectively, which belong to the genus Unuamitovirus within the family Mitoviridae. Phylogenetic analysis based on amino acid sequences supported the classification of NoMV3 as a member of a new species in the genus Unuamitovirus within the family Mitoviridae.

Comparative transcriptomics provides insight into molecular mechanisms of zinc tolerance in the ectomycorrhizal fungus Suillus luteus.

Zinc (Zn) is a major soil contaminant and high Zn levels can disrupt growth, survival, and reproduction of fungi. Some fungal species evolved Zn tolerance through cell processes mitigating Zn toxicity, though the genes and detailed mechanisms underlying mycorrhizal fungal Zn tolerance remain unexplored. To fill this gap in knowledge, we investigated the gene expression of Zn tolerance in the ectomycorrhizal fungus Suillus luteus. We found that Zn tolerance in this species is mainly a constitutive trait that can also be environmentally dependent. Zinc tolerance in S. luteus is associated with differences in expression of genes involved in metal exclusion and immobilization, as well as recognition and mitigation of metal-induced oxidative stress. Differentially expressed genes were predicted to be involved in transmembrane transport, metal chelation, oxidoreductase activity, and signal transduction. Some of these genes were previously reported as candidates for S. luteus Zn tolerance, while others are reported here for the first time. Our results contribute to understanding the mechanisms of fungal metal tolerance and pave the way for further research on the role of fungal metal tolerance in mycorrhizal associations.

Biological control of damping-off by Fusarium oxysporum and F. verticillioides on pine and oak seedlings using edible ectomycorrhizal fungi

The Mediterranean forest has an important ecological and economic role, being holm oak (Quercus ilex), Pyrenean oak (Quercus pyrenaica), umbrella pine (Pinus pinea) and Scot pine (Pinus sylvestris) some of its main tree species. The fungal damping-off disease caused by Fusarium seriously threatens the establishment of these forest species in nurseries and reforestation, requiring the search for environmentally friendly alternatives to control the disease. We have used different species of ectomycorrhizal fungi (EMF) as potential biological control agents (BCAs) effective against the disease: Lactarius sanguifluus, Tricholoma portentosum, Suillus luteus and Agaricus silvicola from Pinus-species, and Leccinum lepidum, Amanita rubescens and Xerocomus ferrugineus from Quercus-species. A direct in vitro confrontation was performed and conidial germination of Fusarium in contact with cell-free filtrates produced by EMF was studied. Le. lepidum was the most effective Quercus-fungus in vitro against F. oxysporum, reducing its growth up to 32 % and its conidial germination up to 87 %. S. luteus was the most effective Pinus-fungus in vitro against F. oxysporum and F. verticillioides, reducing in direct confrontation, reducing its growth up to 30 %. However, La. sanguifluus was the Pinus-fungus that inhibited conidial germination of both pathogens, up to 55 %. In planta trials were carried out with seeds of the four forest species growing on substrate colonized by Le. lepidum (in Q. ilex and Q. pyrenaica seeds, infected by F. oxysporum) or by La. sanguifluus (P. pinea and P. sylvestris seeds, infected by F. oxysporum or F. verticillioides). Only La. sanguifluus was effective in reducing disease caused by F. oxysporum (strain Fo4) on P. sylvestris seeds. Therefore, EMF may be a potential tool in the control of damping-off in forest species, requiring further research.

Suillusgrevillei and Suillus luteus promote lead tolerance of Pinus tabulaeformis and biomineralize lead to pyromorphite.

Lead (Pb) is a hazardous heavy metal that accumulates in many environments. Phytoremediation of Pb polluted soil is an environmentally friendly method, and a better understanding of mycorrhizal symbiosis under Pb stress can promote its efficiency and application. This study aims to evaluate the impact of two ectomycorrhizal fungi (Suillus grevillei and Suillus luteus) on the performance of Pinus tabulaeformis under Pb stress, and the biomineralization of metallic Pb in vitro. A pot experiment using substrate with 0 and 1,000 mg/kg Pb2+ was conducted to evaluate the growth, photosynthetic pigments, oxidative damage, and Pb accumulation of P. tabulaeformis with or without ectomycorrhizal fungi. In vitro co-cultivation of ectomycorrhizal fungi and Pb shots was used to evaluate Pb biomineralization. The results showed that colonization by the two ectomycorrhizal fungi promoted plant growth, increased the content of photosynthetic pigments, reduced oxidative damage, and caused massive accumulation of Pb in plant roots. The structural characteristics of the Pb secondary minerals formed in the presence of fungi demonstrated significant differences from the minerals formed in the control plates and these minerals were identified as pyromorphite (Pb5(PO4)3Cl). Ectomycorrhizal fungi promoted the performance of P. tabulaeformis under Pb stress and suggested a potential role of mycorrhizal symbiosis in Pb phytoremediation. This observation also represents the first discovery of such Pb biomineralization induced by ectomycorrhizal fungi. Ectomycorrhizal fungi induced Pb biomineralization is also relevant to the phytostabilization and new approaches in the bioremediation of polluted environments.

Effects of four bolete species on ectomycorrhizae formation and development in Pinus thunbergii and Quercus acutissima

BackgroundBolete cultivation is economically and ecologically valuable. Ectomycorrhizae are advantageous for plant development and productivity. This study investigated how boletes affect the formation of Pinus thunbergii and Quercus acutissima ectomycorrhizae using greenhouse-based mycorrhizal experiments, inoculating P. thunbergii and Q. acutissima with four species of boletes (Suillus bovinus, Suillus luteus, Suillus grevillei, and Retiboletus sinensis).ResultsThree months after inoculation, morphological and molecular analyses identified S. bovinus, S. luteus, S. grevillei and R. sinensis ectomycorrhizae formation on the roots of both tree species. The mycorrhizal infection rate ranged from 40 to 55%. The host plant species determined the mycorrhiza morphology, which was independent of the bolete species. Differences in plant growth, photosynthesis, and endogenous hormone secretion primarily correlated with the host plant species. Infection with all four bolete species significantly promoted the host plants’ growth and photosynthesis rates; indole-3-acetic acid, zeatin, and gibberellic acid secretion increased, and the abscisic acid level significantly decreased. Indole-3-acetic acid was also detected in the fermentation broths of all bolete species.ConclusionsInoculation with bolete and subsequent mycorrhizae formation significantly altered the morphology and hormone content in the host seedlings, indicating growth promotion. These findings have practical implications for culturing pine and oak tree species.

Elemental Composition of A Cultivated Mushroom (Agaricus bisporus) and Some Wild Mushroom Species

In the study, a cultivation mushroom (Agaricus bisporus) and some wild mushroom species (Schizophyllum commune, Pleurotus ostreatus, Lactarius deliciosus, Hebeloma sinapizans, Hygrophorus ligatus, Suillus luteus, Armillaria mellea, Coprinus comatus, Psathyrella candolleana, Russula torulosa, Trametes pubescens) were investigated in terms of elemental compositions. The wild mushroom species were collected from Trabzon province. Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Rb, Sr, Y, Zr, I, Hf, Hg, Pb metal concentrations were determined using Energy Dispersive X-ray Fluorescence (ED-XRF) device. The highest aliminium, silicium, vanadium, zirconium, iron and mercury were determined in Lactarius deliciosus. The highest potassium, arsenic, rubidium, iodine contents were determined in Hebeloma sinapizans. The highest manganese, zinc, lead contents were determined in Hygrophorus ligatus. The highest magnesium, chromium, nickel, yttrium contents were determined in Coprinus comatus. The highest titanium and selenium were determined in Psathyrella candolleana. The highest calcium and strontium were determined in Russula torulosa. The highest hafnium was determined in Schizophyllum commune. The highest phosphate was determined in Agaricus bisporus. The highest sulphur was determined in Armilleria mella. The highest copper was determined in Suillus lutesus. It was concluded that elemental composition of mushrooms was affected especially by mushroom specie.

Wild mushrooms as potential reservoirs of plant pathogenic bacteria: a case study on Burkholderia gladioli.

Fruit bodies (sporocarps) of wild mushrooms growing in natural environments play a substantial role in the preservation of microbial communities, for example, clinical and food-poisoning bacteria. However, the role of wild mushrooms as natural reservoirs of plant pathogenic bacteria remains almost entirely unknown. Furthermore, bacterial transmission from a mushroom species to agricultural plants has rarely been recorded in the literature. In September 2021, a creamy-white Gram-negative bacterial strain was isolated from the sporocarp of Suillus luteus (slippery jack) growing in Bermuda grass (Cynodon dactylon) lawn in Southern Iran. A similar strain was isolated from the same fungus in the same area in September 2022. Both strains were identified as Burkholderia gladioli based on phenotypic features as well as phylogeny of 16S rRNA and three housekeeping genes. The strains were not only pathogenic on white button mushrooms (Agaricus bisporus) but also induced hypersensitive reaction (HR) on tobacco and common bean leaves and caused soft rot on a set of diverse plant species, that is, chili pepper, common bean pod, cucumber, eggplant, garlic, gladiolus, narcissus, onion, potato, spring onion, okra, kohlrabi, mango, and watermelon. Isolation of plant pathogenic B. gladioli strains from sporocarp of S. luteus in two consecutive years in the same area could be indicative of the role of this fungus in the preservation of the bacterium in the natural environment. B. gladioli associated with naturally growing S. luteus could potentially invade neighboring agricultural crops, for example, vegetables and ornamentals. The potential role of wild mushrooms as natural reservoirs of phytopathogenic bacteria is further discussed.IMPORTANCEThe bacterial genus Burkholderia contains biologically heterogeneous strains that can be isolated from diverse habitats, that is, soil, water, diseased plant material, and clinical specimens. In this study, two Gram-negative pectinolytic bacterial strains were isolated from the sporocarps of Suillus luteus in September 2021 and 2022. Molecular phylogenetic analyses revealed that both strains belonged to the complex species Burkholderia gladioli, while the pathovar status of the strains remained undetermined. Biological investigations accomplished with pathogenicity and host range assays showed that B. gladioli strains isolated from S. luteus in two consecutive years were pathogenic on a set of diverse plant species ranging from ornamentals to both monocotyledonous and dicotyledonous vegetables. Thus, B. gladioli could be considered an infectious pathogen capable of being transmitted from wild mushrooms to annual crops. Our results raise a hypothesis that wild mushrooms could be considered as potential reservoirs for phytopathogenic B. gladioli.

Fruiting characteristics of fungi of the genus Suillus in the artificial pine plantations of the Kedrovsky coal mine dump (Kemerovo region)

The study discusses the fruiting of fungi of the genus Suillus in artificial plantations of Pinus sylvestris L. on the rock dump at the Kedrovsky coal mine (experimental site) and in the pine forests of the Kuzbass Botanical Garden (control site), located on the territory of Kemerovo. The pine plantations at the experimental sites were distributed according to the degree of forest canopy closure. Three sites with different crown closure were identified: sparse closure (20–30%), moderate closure (50–60%), and high closure (80–90%). Within each site, three zones of crown projection were assigned (sub-crown, near-crown, and external). Field studies were carried out during the summer and autumn of 2019. Two species of macromycetes of the genus Suillus are found on the studied sites: Suillus granulatus (L.) Roussel and Suillus luteus (L.) Roussel. Mushrooms growing in pine plantations on reclaimed overburden dumps start fruiting earlier with longer fruiting than that in pine forests on zonal soils. The highest yields of mushrooms are found in pine stands with sparse closure. In the projection of the tree crown, the number of Suillus fungi increases in the direction from the trunk of the tree to the periphery of the crown and beyond (in sparse closures).

In Silico Investigation of Suillin Derived from Suillus luteus Mushroom (Agaricomycetes) Targeting Acetylcholinesterase: Docking and Virtual Screening Study.

This study integrates bioinformatics and computer-aided drug discovery to assess suillin's therapeutic potential, particularly its interaction with acetylcholinesterase (AChE). Alzheimer's disease presents profound challenges, necessitating effective treatments to mitigate cognitive decline and improve patients' quality of life. Although current medications offer symptomatic relief, they often entail adverse effects and do not address the underlying disease progression. Natural sources, such as macrofungi mushrooms, hold promise for novel drug discovery due to their bioactive compounds' diverse therapeutic properties. Suillin, derived from Suillus luteus mushrooms, shows promise as a mixed-type AChE inhibitor, crucial for maintaining acetylcholine levels in neurodegenerative disorders like Alzheimer's disease. Computational docking studies reveal suillin's distinctive interactions with AChE, suggesting potential modulation of enzyme function through various bonding mechanisms. The Molinspiration drug-likeness score further supports suillin's efficacy, indicating its suitability for enzyme inhibition. By combining computational and bioinformatics approaches, this study elucidates suillin's molecular interactions and underscores its potential as a therapeutic agent.

SOURCES OF POLYCYCLIC AROMATIC HYDROCARBONS IN LANDSCAPE COMPONENTS IN THE ZONE AFFECTED BY THE GORLOVO ANTHRACITE DEPOSIT

The content and composition of 19 priority polycyclic aromatic hydrocarbons (PAH) in the rocks and soils of dumps, mushrooms growing on them (Verpa bohemica and Suillus luteus), as well as infiltrated and thawed snow waters on the territory of the Gorlovo anthracite deposit were evaluated. It is shown that the main source of PAH in the components of technogenic and adjacent natural landscapes of the deposit are fine coal particles and products of their transformation of non-pyrogenic nature. The flux of PAH into the components of the environment occurs due to: 1) dust fallout near the road along which the extracted coal is transported; 2) transformation of anthracite inclusions in the upper horizons of coal-bearing soils of dumps; 3) migration of transformation products with infiltrated waters. A distinctive feature of the composition of PAH in the samples of the studied objects is the predominance of light PAH (LPAH) in rocks and coals and heavy PAH (HPAH) in infiltrated and thawed snow waters. The composition of the polyarenes of rocks is dominated by PHE (phenanthrene) > FLT (fluoranthene) > NAP (naphthalene), waters - FLT > PYR (pyrene) > CHR (chrysene). The composition of PAH of soils depends on the presence of coal inclusions. For carbonaceous soils, the predominant polyarenes are FLT > PYR > PHE = CHR. With depth in soils, the composition of PAHs changes and becomes close to the composition of soil-forming rocks. Mushrooms have a selective ability to absorb PAH. Regardless of the presence of coal in the soils on which the mushrooms grow, the predominant compounds are FLT for V. bohemica and PHE for S. luteus. Based on the results of the analysis of the principal components, as well as the correlation of the priority PAH indices with their total content and the content of carcinogenic polyarenes, it has been found that the most representative ratios for assessing the impact of technogenic sources associated with anthracite extraction and transportation are PHE/(PHE + CHR) and ΣLPAH/ΣHPAH.

Green trees preservation: A sustainable source of valuable mushrooms for Ethiopian local communities.

In Ethiopia, Pinus radiata and Pinus patula are extensively cultivated. Both plantations frequently serve as habitats for edible fungi, providing economic and ecological importance. Our study aims were: (i) to investigate how plantation age and tree species influence the variety of edible fungi and sporocarps production; (ii) to determine edaphic factors contributing to variations in sporocarps composition; and (iii) to establish a relationship between the most influencing edaphic factors and the production of valuable edible mushrooms for both plantation types. Sporocarps were collected weekly from permanent plots (100 m2) established in 5-, 14-, and 28-year-old stands of both species in 2020. From each plot, composite soil samples were also collected to determine explanatory edaphic variables for sporocarps production and composition. A total of 24 edible species, comprising 21 saprophytic and three ectomycorrhizal ones were identified. Agaricus campestroides, Morchella sp., Suillus luteus, Lepista sordida, and Tylopilus niger were found in both plantations. Sporocarp yields showed significant variation, with the highest mean production in 28-year-old stands of both Pinus stands. Differences in sporocarps variety were also observed between the two plantations, influenced by factors such as pH, nitrogen, phosphorus, potassium, and cation exchange capacity. Bovista dermoxantha, Coprinellus domesticus, and A. campestroides made contributions to the variety. The linear regression models indicated that the abundance of specific fungi was significantly predicted by organic matter. This insight into the nutrient requirements of various fungal species can inform for a better plantation management to produce both wood and non-wood forest products. Additionally, higher sporocarps production in older stands suggests that retaining patches of mature trees after the final cut can enhance fungal habitat, promoting diversity and yield. Thus, implementing this approach could provide supplementary income opportunities from mushroom sales and enhance the economic outputs of plantations, while mature trees could serve as a source of fungal inoculum for new plantations.

Systematic review of macrofungi biodiversity in Eastern Africa countryside: uses, distribution, and conservation checklists

Abstract. Mushroom biodiversity covers some indispensable non-timber forest products that are wide-spread in Africa, although these resources are currently underutilized, underdeveloped, and left to face the vagaries of climate change and human activities unmanaged. The mushrooms of Eastern Africa have barely been identified or examined for their potential to better the livelihood of the inhabitants. This review of published-online-only literature was carried out to systematically document this biodiversity and its potentials. There were 135 edible mushrooms, 9 edible+medicine mushrooms, and 59 species with no ascribed uses out of 205 species altogether in Eastern Africa. Two mushrooms were identified as poisonous. There were 32 key edible mushrooms in Eastern Africa based on their usage. A tally of mushrooms species (based on country where they were sighted) showed that Ethiopia accounted for 96 species, Tanzania (75), Burundi (37), Rwanda (24), Kenya (18), and Uganda (6) while no information was available from the rest of the countries in the region. The most common genera of mushrooms included Termitomyces, Russula, Pleurotus, Marasmius, Lactarius, Coprinus, Cantharellus, Armillaria, Amanita, and Agaricus. While the most popular species (based on consumption by more locations/tribes) were Amanita zambiana, Hypholoma fasciculare (could be poisonous), Pleurotus cystidiosus, Polyporus tenuiculus, Termitomyces letestui, and Termitomyces striatus. However, it was observed that these tribes or locations were often only within a few countries. Therefore, truly regional mushrooms included Schizophyllum commune (could be poisonous), Suillus luteus, Termitomyces clypeatus, Termitomyces striatus, and Termitomyces microcarpus based on their being found in at least three or more countries. Fungi biodiversity conservation is inadequate in the region.

Virome analysis of an ectomycorrhizal fungus Suillus luteus revealing potential evolutionary implications.

Suillus luteus is a widespread edible ectomycorrhizal fungus that holds significant importance in both ecological and economic value. Mycoviruses are ubiquitous infectious agents hosted in different fungi, with some known to exert beneficial or detrimental effects on their hosts. However, mycoviruses hosted in ectomycorrhizal fungi remain poorly studied. To address this gap in knowledge, we employed next-generation sequencing (NGS) to investigate the virome of S. luteus. Using BLASTp analysis and phylogenetic tree construction, we identified 33 mycovirus species, with over half of them belonging to the phylum Lenarviricota, and 29 of these viruses were novel. These mycoviruses were further grouped into 11 lineages, with the discovery of a new negative-sense single-stranded RNA viral family in the order Bunyavirales. In addition, our findings suggest the occurrence of cross-species transmission (CST) between the fungus and ticks, shedding light on potential evolutionary events that have shaped the viral community in different hosts. This study is not only the first study to characterize mycoviruses in S. luteus but highlights the enormous diversity of mycoviruses and their implications for virus evolution.

Change of microbial communities in heavy metals-contaminated rhizosphere soil with ectomycorrhizal fungi Suillus luteus inoculation

Ectomycorrhizal fungus Suillus luteus has been recognized to harbor the ability of improving rhizosphere soil nutrients and absorbing heavy metals (HMs), but effects of S. luteus inoculation on microbial communities in HM-contaminated rhizosphere soil remain unclear. A comprehensive study involving physicochemical analysis and comparative metagenomics was employed to determine the differences in soil properties, structure and function of microbial communities between inoculation and non-inoculation groups. Results showed that the concentrations of soil organic carbon, total carbon, and total nitrogen of rhizosphere soil in inoculation group were 2.1, 1.7, and 1.3 times as high as that in uninoculated group. Besides, concentrations of Cd, Pb, As, Cu, and Zn in inoculation soil were 79 %, 33 %, 65 %, 14 %, and 51 % lower than that in uninoculated soil. Metagenomic study indicated that S. luteus inoculation had no strong effect on diversity and richness of microbial communities in rhizosphere soil, but increased the relative abundance of certain HM-resistant microorganisms such as phylum Actinobacteria and genus Streptomyces. Metabolism-oriented functional annotation further revealed that in inoculation group the abundance of coding sequences related to nutrients metabolism (e.g., carbon, nitrogen, and sulfur metabolism) and HMs resistance (e.g., HMs transformation and efflux) distinctly differed from that in uninoculated group. In short, our findings may elucidate the potential contribution of S. luteus inoculation that affects the structure composition and metabolic functions of microbial communities to mediate the concentration variation of nutrients and HMs in rhizosphere ecosystem.

In vitro growth of nine edible ectomycorrhizal fungi under a range of pH conditions

Ectomycorrhizal fungi are considered to play an essential role in the development of forest ecosystems and can protect plant against pathogenic infections. Among other factors, soil pH may affect the successful inoculation of forest seedlings in nurseries. The effect of pH on the growth rate of strains of nine species of edible ectomycorrhizal (ECM) fungi was evaluated in vitro. In the experiments, Boletus edulis, B. aereus, B. pinophilus, B. fragrans, Amanita rubescens, Xerocomus ferrugineus, Lactarius deliciosus, Lactarius sanguifluus and Suillus luteus were grown in Petri dishes containing modified Melin Norkrans medium and adjusted at seven different pH levels. Colony area was measured at 7-day intervals for 8 weeks. Final fungal biomass and residual pH of the medium at 8th week were also measured. The optimum pH levels and pH tolerance ranges for the tested ECM fungal species are presented and discussed in the text. The results showed that the greatest growth in vitro was produced by A. rubescens and S. luteus at high pH levels (between 6.5-8.5), and by X. ferrugineus at low pH (3.5-6.5). Almost all the strains acidified the medium where they were grown after eight incubation weeks.

Effect of Ectomycorrhizal Fungi on the Drought Resistance of Pinus massoniana Seedlings.

Studies on the dynamics of non-structural carbohydrates (NSCs) play an important role in understanding the mechanisms of plant responses to drought stress. The objective of this study was to assess the influence of ectomycorrhizal fungi (ECMF) on the content and distribution of NSCs in Pinus massoniana seedlings under different drought intensities and to further explore the possible mechanism by which ECMF enhances the stress resistance of host plants. We conducted a pot experiment using P. massoniana seedlings that were inoculated (M) or non-inoculated (NM) with Suillus luteus (Sl) under well-watered, moderate, and severe drought stress conditions. The results showed that drought significantly reduced the photosynthetic capacity of P. massoniana seedlings and inhibited their growth rate. P. massoniana could respond to different degrees of drought stress by increasing the accumulation of NSCs and increasing WUE. However, compared with well-watered treatment, NSCs consumption began to appear in the roots of NM due to the decrease in starch content under severe drought, whereas NSCs content in M seedlings was higher than that in the well-watered treatment, showing that the ability to maintain C balance was higher in M seedlings. Compared with NM, inoculation with Sl increased the growth rate and biomass of roots, stems, and leaves under moderate and severe drought. In addition, Sl can also improve the gas exchange parameters (net photosynthetic rate, transpiration rate, intercellular CO2 concentration and stomatal conductance) of P. massoniana seedlings compared with NM seedlings, which was conducive to the hydraulic regulation of seedlings and improved their C fixation capacity. Meanwhile, the content of NSCs in M seedlings was higher. Moreover, the soluble sugar content and SS/St ratio of leaves, roots, and whole plants were higher under drought stress after Sl inoculation, indicating that Sl could also change the C distribution mode, regulate more soluble sugar to respond to drought stress, which was conducive to improving the osmotic adjustment ability of seedlings, and providing more available C sources for plant growth and defense. Overall, inoculation with Sl could enhance the drought resistance of seedlings and promote their growth under drought stress by improving NSCs storage, increasing soluble sugar distribution, and improving the plant water balance of P. massoniana seedlings.