Mycorrhizal Seedlings Research Articles

One New Host Records of Apiospora arundinis From Lactarius vividus

In this investigation, morphological traits and phylogenetic analyses of multiple genes, including ITS, 28S, tub2, and tef1, were employed to classify a companion fungus extracted from the fresh fruiting bodies of Lactarius vividus in China. The fungus was identified as Apiospora arundinis, marking the first instance of its isolation from a mushroom. Subsequent research into its biological characteristics revealed that the mycelium was the optimal condition of 30 oC, pH7 and grew well in medium containing soluble starch and peptidic sugars. It was also observed that this fungus was resent in the fruiting bodies of Lactarius vividus, and its hyphal growth was influenced by temperature, pH, and media composition. These findings lay a foundation for additional research and practical applications of Apiospora arundinis, which are of great significance for the storage and preservation of Lactarius vividus, guiding the cultivation of mycorrhizal seedlings, and exploring the mechanism and mechanism, but the specific principles need to be further explored.

Arbuscular mycorrhizal fungi enhance drought resistance in Bombax ceiba by regulating SOD family genes.

The physiological activity facilitated by arbuscular mycorrhizal fungi (AMF) contributes to plants' ability to tolerate drought. Nevertheless, it is unclear if AMF colonization affects the expression of genes in the host plant that encode antioxidant enzymes in the superoxide dismutase (SOD) family, which help alleviate drought stress in plants. Here, we conducted a pot trial to determine whether colonization by the AMF Rhizophagus irregularis improves drought resistance in Bombax ceiba. We comprehensively analyzed the SOD gene family and evaluated genome-wide expression patterns of SODs and SOD activity in AMF-colonized and non-mycorrhizal plants under simulated drought. We identified a total of 13 SODs in the genome of B. ceiba, including three FeSODs (BcFSDs), three MnSODs (BcMSDs), and seven Cu/ZnSODs (BcCSDs). Phylogenetic analysis based on binding domain revealed that SOD genes from B. ceiba and various other plant species can be divided into three separate groups, showing significant bootstrap values. Our examination of gene composition and patterns suggests that most BcSOD genes in these three subgroups are significantly conserved. Additionally, it was noted that hormones and stress-responsive cis-regulatory elements were found in all BcSOD promoters. Expression profiling by qRT-PCR demonstrated that AMF increased relative expression levels of Cu/Zn-SODs in both roots and shoots under drought stress, except for BcCSD3 in roots. Furthermore, AMF colonization increased the relative expression of BcMSD1a and BcMSD1b in roots, augmenting SOD activities and increasing ROS scavenging during drought. In general, this work offers molecular evidence in support of the beneficial effect of AMF colonization on drought tolerance in B. ceiba. It also elucidates the expression patterns of SOD genes, which will support efforts to optimize mycorrhizal seedling cultivation under stressful conditions.

Impact of three distinct mycorrhizal species on Cedrus libani seedling development and nutrient uptake

Aim of study: In semi-arid afforestation sites, the study aimed to create mycorrhizal seedlings with high vitality, health, and tolerance to harsh environments. The study's hypotheses state that mycorrhizal inoculation will improve Cedrus libani (Taurus cedar) seedlings' growth characteristics, nutrition, root colonization, and mycorrhizal reliance. Area of study: The Eastern Mediterranean Research Institute laboratory and greenhouse in Tarsus district-Mersin, Türkiye. Material and methods: The experiment involved inoculation of three ectomycorrhizal fungal species (Lactarius delicious, Hebeloma crustuliniforme, Tricholoma ustale) collected from natural cedar stands on to cedar seedlings grown in two different substrates (sterilized, non-sterilized. Inoculation was carried out by dipping the roots of Cedrus libani A. Rich (Taurus cedar) seedlings into mycorrhizal mycelia. Main results: Cedar seedlings infected with mycorrhiza exhibited a greater biomass ratio in comparison to the control seedlings. Substrate sterilization increased seedling growth variables. The highest growth, some nutrients such as N, P, K, Fe and Zn uptake, root colonization and mycorrhizal dependence occurred in seedlings with H. crustuliniforme and L. delicious. Research highlights: Although this study is limited to Taurus cedar-mycorrhiza combinations, it may also be applicable to different mycorrhizal fungal species and many other valuable host tree species. More research is needed on the adaptation of different mycorrhizal species to habitats to increase the success of afforestation efforts in arid and semi-arid regions.

Positive interaction of trembesi (Samanea saman) and arbuscular mycorrhizae fungi in Pb stabilization of gold-mine tailing media

Abstract. Setyaningsih L, Ramadhani FA, Muttaqin Z, Maslahat M. 2024. Positive interaction of trembesi (Samanea saman) and arbuscular mycorrhizae fungi in Pb stabilization of gold-mine tailing media. Biodiversitas 25: 379-385. This experiment aimed to determine the ability of trembesi (Samanea saman Merr.) seedlings inoculated with AMF (Glomus manihotis) to reduce Pb from gold mine tailings media. Therefore, using plants and Arbuscular Mycorrhizae Fungi (AMF) is an alternative choice that can be considered to support a phytoremediation program to reduce Pb contamination in tailing areas. The experiment was conducted using a completely randomized design in a greenhouse with two factors, i.e., with and without AMF, and four different Pb treatments (0, 0.5, 1, and 1.5 mM). AMF-inoculated seedlings were grown on tailings media and exposed to Pb in different concentrations for 5 weeks. The results showed that the seedlings were still able to grow on the media with Pb up to 1.5 mM with a tolerance index of 91.6%. AMF induced the plant to accumulate Pb dramatically higher, even though this absorption tended to reduce plant biomass. Root tissue stored significantly higher Pb than stem and leaf tissue, with an average concentration was 526.29 mg/kg in the roots of mycorrhizal seedlings. The bioaccumulation level of Pb in mycorrhizal seedlings was significantly higher. The value of the transport factor was below 1, indicating that S. saman seedlings carried out the phytostabilization. The interaction of AMF with S. saman has a big potential to be applied in efforts to remediate Pb in tailings.

Physiological and Transcriptome Responses of Pinus massoniana Seedlings Inoculated by Various Ecotypes of the Ectomycorrhizal Fungus Cenococcum geophilum during the Early Stage of Drought Stress.

The impact of drought stress on plant growth in arid regions is a critical concern, necessitating the exploration of strategies to enhance plant drought resistance, particularly during the early stages of drought stress. This study focuses on the ectomycorrhizal fungus Cenococcum geophilum, renowned for its extensive genetic diversity and broad host compatibility, making it a crucial ally for host plants facing external stresses. We utilized Pinus massoniana seedlings inoculated with different ecotypic strains of C. geophilum under drought stress. The results showed that the inoculation of most strains of C. geophilum enhanced the drought resistance of P. massoniana seedlings under the early stages of drought stress, by influencing the water content, photosynthesis, accumulation of osmotic adjustment substances, and antioxidant enzyme activities in both shoots and roots of seedlings. Transcriptome analysis showed that mycorrhizal seedlings mainly regulated energy metabolism and reduction-oxidation reaction to resist early drought stress. Notably, the level of drought resistance observed in mycorrhizal seedlings was irrespective of the level of drought tolerance of C. geophilum strains. This study contributes essential data for understanding the drought response mechanisms of mycorrhizal P. massoniana seedlings inoculated by distinct C. geophilum ecotypes and guidance on selecting candidate species of ectomycorrhizal fungi for mycorrhizal afforestation in drought areas.

Arbuscular mycorrhizal and ectomycorrhizal plants together shape seedling diversity in a subtropical forest

IntroductionBurgeoning mycorrhizal research has focused on identifying the various diverse mycorrhizal strategies of forest communities. Mounting evidence suggests that mycorrhizae play important roles in regulating forest community structure and composition. However, research into the manifestation of this influence in the seedling stage is lacking, especially in small-scale plots.MethodsOur research utilized structural equation models parameterized using data from a subtropical monsoon broad-leaved evergreen forest situated in Yunnan Province, China.ResultsWe noted that seedlings included plants that utilized both arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) fungi. More seedling plots with the relatively higher species diversity were the product of the mixed mycorrhizal strategy, meaning the coexistence of AM and EM seedlings in a small-scale plot rather than the dominance of one type of strategies. These mixed communities were primarily found on slopes and mountain ridges. The abundance of AM or EM trees indirectly affected seedling diversity by influencing the abundance of different mycorrhizal seedlings. In this case, the diversity of the mixed mycorrhizal community was also restricted by the level of leaf thickness in the community, followed by abiotic factors such as elevation, convexity, soil pH and soil available phosphorus.DiscussionThe effect of leaf thickness on mycorrhizal seedling abundance reflected the importance of water conditions in shaping seedling communities. The effect of convexity on seedling diversity also reflected the limitation of seedling communities by the distribution of humidity and heat conditions during topographic change. The results suggested that it is crucial to preserve seedling diversity via the mixed mycorrhizal strategy of communities in the subtropical forest.

Metal-non-tolerant ecotypes of ectomycorrhizal fungi can protect plants from cadmium pollution.

The application of mycorrhizal fungi as a bioaugmentation technology for phytoremediation of heavy metal (HM) contaminated soil has attracted widespread attention. In order to explore whether the adaptation of Pinus massoniana (P. massoniana) to metal polluted soil depends on the metal adaptation potential of their associated ectomycorrhizal fungi (ECMF), we evaluated the cadmium (Cd) tolerance of 10 ecotypes of Cenococcum geophilum (C. geophilum) through a membership function method, and P. massoniana seedlings were not (NM) or inoculated by Cd non-tolerant type (JaCg144), low-tolerant (JaCg32, JaCg151) and high-tolerant (JaCg205) isolates of C. geophilum were exposed to 0 and 100 mg·kg-1 for 3 months. The result showed that, each ecotype of C. geophilum significantly promoted the growth, photosynthesis and chlorophyll content, proline (Pro) content and the activity of peroxidase (POD) of P. massoniana seedlings, and decreased malonaldehyde (MDA) content and catalase (CAT) and superoxide dismutase (SOD) activity. The comprehensive evaluation D value of the tolerance to Cd stress showed that the order of the displaced Cd resistance of the four ecotypic mycorrhizal P. massoniana was: JaCg144 > JaCg151 > JaCg32 > JaCg205. Pearson correlation analysis showed that the Sig. value of the comprehensive evaluation (D) values of the strains and mycorrhizal seedlings was 0.077 > 0.05, indicating that the Cd tolerance of the the C. geophilum isolates did not affect its regulatory effect on the Cd tolerance of the host plant. JaCg144 and JaCg151 which are non-tolerant and low-tolerant ecotype significantly increased the Cd content in the shoots and roots by about 136.64-181.75% and 153.75-162.35%, indicating that JaCg144 and JaCg151 were able to effectively increase the enrichment of Cd from the soil to the root. Transcriptome results confirmed that C. geophilum increased the P. massoniana tolerance to Cd stress through promoting antioxidant enzyme activity, photosynthesis, and lipid and carbohydrate synthesis metabolism. The present study suggests that mental-non-tolerant ecotypes of ECMF can protect plants from Cd pollution, providing more feasible strategies for ectomycorrhizal-assisted phytoremediation.

European Tuber melanosporum plantations: adaptation status in Hungary, mycorrhizal level, and first ascocarp detection in two truffle orchards

Tuber melanosporum is one of the most economically important truffle species. Besides harvesting from its natural habitats, this truffle can also be extensively grown through artificial cultivation. However, the natural habitat of T. melanosporum has drastically declined, and the demand for the truffle in society is rapidly increasing. Therefore, enhancing production in truffle orchards by seeking new places for the establishment and regularly monitoring its adaptability might be an effective method for ensuring the sustainable productivity of the species. As a truffle science, recent information is important to further success in the growth of this truffle species. This study reports mycorrhization level and ascocarp production in two truffle plantations in Hungary. The estimated mycorrhization levels of the host plants were 43.36% in Biatorbágy and 42.93% in Jászszentandrás plantations. In March 2020, the 6-year-old and 18-year-old T. melanosporum plantations yielded around 100 g and 980 g of ascocarps, respectively. In general, adaptation of mycorrhizal seedlings in Hungary may become more effective as present management practices improve.

Effects of Truffle Inoculation on Root Physiology and Mycorrhizosphere Microbial Communities of Carya illinoinensis Seedlings

Although they are a valuable edible ectomycorrhizal fungus, truffles (Tuber spp.) nevertheless face significant difficulties in the development of their scale. As a type of high economic value nut-like economic forest tree, the pecan (Carya illinoinensis) serves as a natural host for truffles. However, the technology for mycorrhizal synthesis in pecan has not yet been developed, and it is still unclear how certain microbes affect this process. In this study, we inoculated the pecan root system with a suspension of truffle spores and investigated the growth physiology of pecan seedlings with various infestation levels, as well as changes in the soil’s physicochemical properties and the makeup of the microbial community at the root level. The findings showed that tuber inoculation significantly increased the peroxidase activity of the pecan root system, significantly decreased the pH, and effective phosphorus content of mycorrhizosphere soil, while increasing the nitrate nitrogen content, and significantly increased the abundance and diversity of the mycorrhizosphere soil fungal community. Different groups of fungal and bacterial markers were formed in the mycorrhizosphere of pecan seedlings at different levels of infestation. In the highly infested group, Rozellomycota and lasiosphaeriaceae were the difference marker fungi, and Xanthobacteraceae, Rhizobiaceae as well as Streptococcaceae were the difference marker bacteria. In the low-infestation group, sphaerosporella was differential marker fungi, and Bacillus and Tumebacillus were differential marker bacteria. The fungal marker flora of the control group consisted of Chaetomium and Gilmaniella. Pseudomonas was the marker bacterial community. Additionally, these fungi included Collarina and Rozellomycota, and several bacteria from the genera Pseudomonas, Gemmatimonas, and others showed highly significant relationships with changes in soil pH, effective phosphorus, and nitrate nitrogen. In conclusion, pecan–truffle mycorrhizal seedlings have the potential to create the ideal microbial community structure needed for mycorrhizal growth, and these microorganisms have the potential to significantly alter the pH, effective phosphorus content, and nitrate nitrogen concentration of the mycorrhizosphere soil. Our results contribute to the understanding of how the mycorrhizosphere microbial community evolves when exogenous mycorrhizal fungi infest host plants and can offer some theoretical guidelines for growing pecan–truffle mycorrhizal seedlings.

Modification of Density Dependence and Habitat Filtering on Seedling Survival of Different Mycorrhizal-Type Tree Species in Temperate Forests

Conspecific negative density dependence (CNDD) and habitat filtering are critical to seedling survival. However, the relative importance of the two processes in affecting survival of seedlings with different types of mycorrhizae remains unclear. In this study, the effects of CNDD and habitat filtering on the survival of tree seedlings with different mycorrhizal types were investigated at different successional stages of a temperate forest in the Changbai Mountain Natural Reserve, Northeast China. Conspecific negative density dependence and habitat filtering significantly affected seedling survival. In the early successional stage, the interactions between conspecific neighbor tree density and light availability and soil properties significantly negatively affected survival of all species and arbuscular mycorrhizal (AM) seedlings in the community, but not that of ectomycorrhizal (EcM) seedlings, and the CNDD effect was stronger on AM seedlings than on EcM seedlings. In the mid-successional stage, CNDD effects were stronger on EcM seedlings. Therefore, different types of mycorrhizal seedlings responded differently to CNDD and habitat filtering mechanisms during community succession, and thus, tree mycorrhizal association could determine the effects of CNDD and habitat filtering on seedling survival in temperate forests.

Effects of combinations of arbuscular mycorrhizal fungal species on tomato growth and Fusarium wilt control

In this study, we investigated the effects of combinations of arbuscular mycorrhizal (AM) fungal species on tomato seedling growth and Fusarium wilt control. The study was conducted in greenhouse pot experiments using the tomato (Solanum lycopersicum) variety Fusan 88 and the fungi Funneliformis mosseae, Diversispora versiformis, Claroideoglomus etunicatum, and Rhizophagus intraradices as inoculants. The results showed higher mycorrhizal root colonization rates in all inoculation mixtures than in single-inoculum treatments, while growth-promotion effects differed significantly among AM fungal species and their combinations. Except for inoculation with F. mosseae alone, other inoculation treatments significantly promoted the growth of tomato seedlings. Of all fungal species, R. intraradices had the most significant effect on promoting seedling growth, as observed in all inoculum combinations containing this species. The greatest effect on seedling growth was observed for combined inoculation with D. versiformis + R. intraradices, which led to increases in above- and belowground biomass of 67.74 % and 100 %, respectively, compared to the control (CK), followed by C. etunicatum + R. intraradices, which led to increases in above- and belowground biomass of 61.29 % and 100 % compared to CK. Redundancy analyses showed that compared to the other three species, R. intraradices had more significant effects on promoting plant nitrogen, phosphorus, and potassium uptake and increasing above- and belowground dry weight. Mycorrhizalized seedlings were more resistant to Fusarium wilt and had lower malondialdehyde content and higher catalase, superoxide dismutase, and polyphenol oxidase activity in tomato plants. The lowest Fusarium wilt disease index value was 39.96 %, for mixed inoculation with F. mosseae + D. versiformis + C. etunicatum; this was 34.28 % lower than that of CK, and the control effect was 34.27 %, followed by inoculation with C. etunicatum + R. intraradices, which had a disease index value of 41.48 %, 31.78 % lower than that of CK, with a control effect value of 31.76 %. Therefore, we transplanted tomato seedlings inoculated with C. etunicatum + R. intraradices, which had both good growth-promotion and disease-resistance effects, to a greenhouse for sand culture under conditions of high water and fertilization. The mycorrhizal relationships developed in these plants at the seedling stage remained stable throughout the tomato reproductive period. The mycorrhizal seedlings had a significantly lower incidence of Fusarium wilt and lower disease index values, indicating better disease control than observed in non-mycorrhizal seedlings. The mycorrhizal plants produced fruits with a significantly higher soluble-sugar content and sugar:acid ratio (30.8 % and 42.3 % higher, respectively, than CK) and a significantly lower organic acid content (11.5 % lower than CK). Thus, mycorrhization significantly improved tomato plants’ growth, disease resistance, and fruit quality. These findings lay a foundation for the application of mycorrhizal fungi in tomato agriculture.

Sequential application of inoculation methods improves mycorrhization of Quercus ilex seedlings by Tuber melanosporum

The use of mycorrhized seedlings has been critical to the success of modern truffle cultivation, which nowadays supplies most European black truffles (Tuber melanosporum) to markets. Ascospore inoculation has been traditionally used to produce these seedlings, but little scientific information is publicly available on the inoculation methods applied or on the possibility of combining them. We evaluated the potential of sequential inoculation for the controlled colonization of holm oak fine roots by T. melanosporum, with two different nursery assays and a full factorial design. Three inoculation methods were sequentially applied: radicle inoculation, inoculation of the substrate in seedling trays and inoculation of the substrate in the final pot. Despite the differences in the results of the two assays, which suggest that cultivation conditions and/or the timing of nursery operations may influence the relative effectiveness of inoculation methods, the sequential application appeared as an effective and realistic alternative for commercial inoculation of holm oak seedlings with T. melanosporum. The increase in the amount of inoculum applied with each inoculation method improved the mycorrhizal colonization of seedlings, whereas separately none of the inoculation methods appeared clearly superior to the other ones. The depth distribution of truffle mycorrhizae pointed that the inoculation in the final pot was more effective than other methods in lower parts of the root system, whereas the early inoculation appeared more effective to reduce the occurrence of the opportunist ectomycorrhizal fungus Sphaerosporella brunnea.

Anatomical responses of leaf and stem of Catalpa bungei C.A.Mey. to nitrogen application and Rhizophagus intraradices inoculation

Plant morphology and anatomical structure are closely related to plant function, and their changes may affect physiological processes and may also be altered by nutrient availability or arbuscular mycorrhizal fungi (AMF) inoculation. To our knowledge, studies on the effect of AMF on plant anatomical characteristics under different nitrogen (N) levels are very scarce, especially in trees. Here, a pot experiment was carried out to evaluate the response of leaf and stem anatomy of Catalpa bungei using a two-factor completely randomized block design, including mycorrhizal inoculation (inoculation with Rhizophagus intraradices or not) and N application (low, medium, high). Regardless of the inoculation status, moderate N addition promoted leaf and stem development, while excessive N had a significant negative impact on the anatomical structure of seedlings. Compared with the non-inoculated treatments, AMF inoculation increased most of the leaf stomatal characteristic parameters and stem structural parameters of C. bungei seedlings, while significantly reduced leaf upper epidermis thickness (UET), lower epidermis thickness (LET), spongy tissue thickness (STT), and leaf thickness (LT) at low to medium N levels. In addition, the lenticel density (LD) at low N levels and the lenticel length (LL), width (LW), and area (SLA) at medium N levels in mycorrhizal seedlings were significantly higher than those in non-mycorrhizal seedlings. We concluded that AMF inoculation may significantly improve the water and gas exchange capacity of seedlings at least at low to medium N levels.

Insights on the Impact of Arbuscular Mycorrhizal Symbiosis on Eucalyptus grandis Tolerance to Drought Stress.

Drought stress has a negative impact on plant growth and production. Arbuscular mycorrhizal (AM) fungi, which establish symbioses with most terrestrial vascular plant species, play important roles in improving host plant mineral nutrient acquisition and resistance to drought. However, the physiological and molecular regulation mechanisms occurring in mycorrhizal Eucalyptus grandis coping with drought stress remain unclear. Here, we studied the physiological changes and mitogen-activated protein kinase (MAPK) cascade gene expression profiles of E. grandis associated with AM fungi under drought stress. The results showed that colonization by AM fungi significantly enhanced plant growth, with higher plant biomass, shoot height, root length, and relative water content (RWC) under drought conditions. Mycorrhizal plants had lower levels of accumulation of proline, malondialdehyde (MDA), H2O2, and O2·- than seedlings not colonized with AM fungi. In addition, mycorrhizal E. grandis also had higher peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) activities under drought conditions, improving the antioxidant system response. Eighteen MAPK cascade genes were isolated from E. grandis, and the expression levels of the MAPK cascade genes were positively induced by symbiosis with AM fungi, which was correlated with changes in the proline, MDA, H2O2, and O2·- contents and POD, SOD, and CAT activities. In summary, our results showed that AM symbiosis enhances E. grandis drought tolerance by regulating plant antioxidation abilities and MAPK cascade gene expression. IMPORTANCE Arbuscular mycorrhizal (AM) fungi play an important role in improving plant growth and development under drought stress. The MAPK cascade may regulate many physiological and biochemical processes in plants in response to drought stress. Previous studies have shown that there is a complex regulatory network between the plant MAPK cascade and drought stress. However, the relationship between the E. grandis MAPK cascade and AM symbiosis in coping with drought remains to be investigated. Our results suggest that AM fungi could improve plant drought tolerance mainly by improving the antioxidant ability to protect plants from reactive oxygen species (ROS) and alleviate oxidative stress damage. The expression of the MAPK cascade genes was induced in mycorrhizal E. grandis seedlings under drought stress. This study revealed that MAPK cascade regulation is of special significance for improving the drought tolerance of E. grandis. This study provides a reference for improving mycorrhizal seedling cultivation under stress.

Evaluation of Pecan [Carya illinoinensis (Wangenh.) K. Koch] Cultivars for Possible Cultivation for Both Fruit and Truffle Production in the Puglia Region, Southeastern Italy

Yield and different nut parameters were measured for two growing seasons on mature (28–29 years) trees of 11 pecan cultivars grown in an experimental orchard located in the Puglia Region, Southeastern Italy. ‘Shoshoni’ and ‘Shawnee’ pecan seedlings were inoculated with three truffle species (Tuber borchii—known as the ‘whitish truffle’, T. aestivum—called the ‘summer truffle’, and T. melanosporum—the common ‘Black truffle’) and investigated for six months. The level of ectomycorrhizal colonization was assessed 6 and 12 months after inoculation. Results indicated that ‘Wichita’, ‘Shoshoni’, and ‘Pawnee’ performed well in the pedoclimatic conditions of the area with a yield higher than 20 kg/tree and a kernel dry weight of ≅3 g. These preliminary yield results suggested that some pecan cultivars could deserve consideration for cultivation in the Puglia Region, whereas others with low yield and a stronger alternate bearing should not be considered. Plant height, number of leaves, chlorophyll content (expressed as a SPAD unit) and stem diameter partially indicated the increase in ecological fitness in truffles-inoculated plants. Successful mycorrhization indicated ‘Shoshoni’ and ‘Shawnee’ as suitable to establish ectomycorrhizal symbiosis with T. aestivum, T. borchii, and T. melanosporum cultivation under Puglia climatic conditions. The results also showed that the applied protocol was adequate to obtain healthy mycorrhized seedlings appropriate for commercialization and plantation for truffles production on pecan in the future.

Mycorrhizal Fungi Synergistically Promote the Growth and Secondary Metabolism of Cyclocarya paliurus

Cyclocarya paliurus has traditionally been used as medicine or a nutraceutical food. This study aims at investigating whether the growth and secondary metabolism of C. paliurus could be simultaneously promoted by inoculating with mycorrhizal fungi, and if so, to uncover the underlying regulatory mechanism. A mycorrhizal microbial inoculum, consisting of the superficial layer fine roots and rhizosphere soil collected from the natural forest of C. paliurus, was used to infect aseptic seedlings of C. paliurus. Roots of aseptic seedlings were successfully infected by mycorrhizal fungi with a 59.7% colonization rate. For mycorrhizal seedlings of C. paliurus, the induced endogenous auxin, net photosynthetic rate, nitrogen absorption, and growth-related genes resulted in a significantly higher growth and biomass accumulation. In addition, a systemic defense response was observed in response to mycorrhizal fungal colonization, such that jasmonic acid biosynthesis and signaling were induced and the biosynthesis of secondary metabolites and antioxidant systems were up-regulated. The improved growth and accumulation of secondary metabolites ultimately facilitated the yield of health-promoting substrates per plant. Overall, mycorrhizal fungal colonization had a significant positive effect both on growth and production of secondary metabolites in C. paliurus. The results can provide the basis for overcoming the limitation of soil nutrient regulation in cultivation practice and offering a simpler alternative to improve the quality of medicinal plants.

Ectomycorrhizal fungi enhance salt tolerance of Quercus mongolica by regulating ion balance

We explored the effects of salt stress on the growth of Quercus mongolica and the effects of ectomycorrhizal fungi (ECMF) on the ion balance of Q. mongolica. After inoculating four kinds of ECMFs (Gomphidius visci-dus, Suillus leteus, Suillus grevillea, Boletus edulis) on Q. mongolica seedlings, we treated the annual non-mycorrhizated and mycorrhizated seedlings with NaCl stress (0, 100, 200, 300 mmol·L-1) for 36 days, and then analyzed the mycorrhizal characteristics, growth, leaf injury symptoms, leaf electrolyte permeability, water content, and ion contents in roots, stems, and leaves. The results showed that the four ECMFs could establish a symbiotic system with Q. mongolica, and that root system of mycorrhizal seedlings was stronger than that of non-mycorrhizal seedlings. Under salt stress, the growth of Q. mongolica seedlings was inhibited, with the symptoms of scorched leaves. The damage to leaf plasma membrane and the degree of water loss were aggravated with the increases of salt stress. Under low salt stress (100 mmol·L-1), Q. mongolica preferentially accumulated Na+ in roots and stems. Under medium-high salt stress (200-300 mmol·L-1), roots became the primary organ for accumulating Na+. ECMF regulated ion balance in plant by increasing the Na+ level in roots and reducing the Na+ accumulation in stems and leaves, enhancing the absorption of K+ and Ca2+ to increase the K+/Na+ and Ca2+/Na+. The four ECMFs had different mitigation effects on salt poisoning of Q. mongolica. G. viscidus had the strongest effect, followed by S. leteus, while S. grevillei and B. edulis had relatively little effect.

Arbuscular mycorrhizal fungi improve nutrient status of Commiphora myrrha seedlings under drought

In dryland ecosystems, tree and shrub seedling establishment, growth and survival are limited by access to water and nutrients. Arbuscular mycorrhizal fungi (AMF) increase seedling establishment and survival by enhancing nutrient and water acquisition. We executed a fully-factorial greenhouse experiment to determine the interactive effect of AMF (with and without), water deficit (four levels), and soil layer (topsoil and subsoil) on the biomass, growth, nutrient concentrations, and mycorrhizal root colonization of seedlings of Commiphora myrrha, a tree species that dominates large areas of dry forest and woodland in the Horn of Africa. Mycorrhizal seedlings had higher root and shoot biomass than non-mycorrhizal seedlings. They also had higher nutrient concentrations in root and shoot. Plant biomass was higher when plants were grown in topsoil at lower soil moisture levels. Mycorrhizal responsiveness was highest at lower soil moisture. The drought response index was higher for mycorrhizal than for non-mycorrhizal plants, indicating enhanced mycorrhizal benefits at lower water supply. Seedlings grew better in topsoil than in subsoil. Mycorrhizal colonization of roots of C. myrrha seedlings was higher with lower moisture and higher in topsoil than in subsoil. The increased performance of mycorrhizal C. myrrha indicates that mycorrhization is a major component of the adaptive strategy of seedlings of this species, similar to other species in these dryland deciduous ecosystems. We conclude that for restoration purposes with this species, nursery seedlings should be mycorrhized because of their enhanced growth performance.

Short-Term Evaluation of the Spatial Distribution of Trophic Groups of Amoebae in the Rhizosphere of Zea mays Inoculated with Rhizophagus intraradices.

Primary production in terrestrial ecosystems is sustained by plants, microbiota, and fungi, which are the major organic matter providers in the root zone, setting in motion the soil food webs. Predators like soil amoebae voraciously feed on bacteria, fungi, and microbial eukaryotes releasing the nutrients sequestered in their biomass. Early food web setting up is crucial for seedling nutrition and its further development after establishment. Mycorrhizal fungi are more than phosphorus providers, and we wonder what their role is in structuring the predators' trophic groups in the root zone. We evaluated the effect of Rhizophagus intraradices inoculated in Zea mays (mycorrhizosphere), on the structuration of amoebae trophic groups along vertical and horizontal (3, 6, and 9cm) soil distribution when compared to un-inoculated plants, after 20days in microcosms. Amoebae species richness was highest in non-mycorrhizal seedlings in the root zone at 6- to 9-cm depth, and 3cm away from plants. More bacterial species are needed when plants are devoid of mycorrhiza, and their influence is constrained 3cm away from roots. Higher diversity of trophic groups was recorded at mycorrhizal seedlings and at the compartment influenced by the mycelium at 6- to 9-cm depth. The highest bacterivorous diversity, higher number of rare species and protozoa-eating amoebae, and the absence of fungivorous group recorded at the mycorrhizosphere of Z. mays, indicate that the community was very different from the non-mycorrhizal plants. We conclude that the arbuscular mycorrhizal fungus exerts significant changes on the community of trophic groups of amoebae.

A high-quality genome assembly of Lactarius hatsudake strain JH5.

Lactarius hatsudake is a species of Lactarius commonly found in pine forests, is edible with a delicious and nutritious fruiting body, and exhibits medicinal properties. It is an ideal natural multifunctional food with bioactive components including fungal polysaccharides, crude fiber, unsaturated fatty acids, nucleic acid derivatives, various amino acids, and vitamins. However, biological and genomic analyses of this mycorrhizal mushroom are sparse, thereby hindering large-scale cultivation. Previously, we isolated and screened L. hatsudake JH5 strains and have applied our garnered knowledge to the large-scale cultivation of mycorrhizal seedlings. In this study, we produced a high-quality genome assembly of L. hatsudake JH5 by combining Illumina paired-end and PacBio single molecule real-time sequencing, resulting in PacBio single molecule real-time reads of 7.67 Gb and Illumina Pair-End reads of 1,560 Mb. Based on the distribution of k-mer frequencies, the genome size of this strain was estimated to be 63.84 Mb (1.14% heterozygosity). Based on de novo genome assembly, the final genome size was determined to be 76.7 Mb, with scaffold N50 of 223.2 kb and N90 of 54.5 kb, and a GC content of 54.38%. BUSCO assessment showed that genome completeness was 89.0%. The N50 length of the JH5 genome was 43.6% longer than that of the previously published L. hatsudake MG20 genome. This high-quality L. hatsudake genome assembly will facilitate research on the functional genome, molecular breeding, yield enhancement, and sustainability of L. hatsudake cultivation.