Mycorrhiza最新文献

Arbuscular mycorrhizal fungi (AMF) play a crucial role in enhancing the health and productivity of host plants, including grapevine. By forming symbiotic relationships with plant roots, AMF significantly improve water uptake and nutrient absorption, particularly phosphorus (P) and nitrogen (N). This study evaluated the microbiome composition and AMF colonization in the grapevine endorhizosphere across five wine-growing sub-regions in the Czech Republic. In all five sub-regions, in terms of composition of the fungal microbiome, the phyla Ascomycetes and Basidiomycetes were most numerous. Additionally, the study confirmed that LSU primers are more sensitive than ITS primers for AMF sequencing. While the representation of the phylum Glomeromycetes ranged from 0.07% to 5.65% in the ITS library, it was significantly higher, ranging from 83.74% to 98.71%, in the LSU library. The most significant difference compared to other sub-regions was observed in the Slovácko sub-region, where the soil had a low pH, a different texture (sandy loam), reduced micronutrient concentration, and low organic matter. The application of chemical plant protection products to grapevines also could have played a significant role, with 49 applications recorded in the Slovácko sub-region during the three years preceding sample collection. In other sub-regions, chemical treatments were conducted only 19-26 times. These factors resulted in only trace amounts of AMF being detected in Slovácko. Furthermore, it was demonstrated that AMF positively influenced the phosphorus concentration in the soil and reduced the presence of certain fungal pathogens.

Taxonomy of arbuscular mycorrhizal fungi (Glomeromycota) historically has been based mostly on analyses of spore morphology. Molecular evidence has been widely used in phylogeny since the turn of the century and has contributed to the nomenclature of arbuscular mycorrhizal fungi. Considering that some species were described solely from field collected spores which often are degraded, synonymy amongst described species is likely. Type and living cultures of Rhizophagus clarus and Rhizophagus manihotis, and protologue of Glomus zaozhuangianus were analyzed to compare spore wall structure. Sequences of the large subunit (LSU) of the rDNA gene of living isolates of Rhizophagus clarus and Rhizophagus manihotis also were used to test phylogenetic relationships. A comprehensive biogeography of arbuscular mycorrhizal fungi was used to investigate species distribution according to soil and climate factors. Spore wall structure analysis indicates that the three species are morphologically indistinguishable. Spore color, size, and shape all overlap highly among the three species. The spore wall of each is composed of an outer hyaline mucilaginous layer, a rigid hyaline laminated layer conferring a visible "halo" to mature spores, and a third rigid pigmented laminated layer that confers spore color. Phylogenetic analysis shows that living isolates identified as R. manihotis were nested with living isolates of R. clarus, forming a monophyletic clade with 99% bootstrap support. Spores of R. clarus (as amended here) have been recorded in six continents and 31 countries in 10 biogeographical realms. R. clarus was detected most often in soil pH 5.0-6.0, soil P up to 5 mg/dm³, and soil organic matter up to 2.5%. Polynomial models indicate that the probability of occurrence of R. clarus is optimized at a temperature of 20^o C and 2,000 mm precipitation.

Under saline-alkali stress conditions, inoculation with Rhizophagus irregularis or the application of biochar can both promote plant growth and improve soil physicochemical properties. However, the effects of their combined use on switchgrass growth and soil mechanical properties remain unclear. This study established four treatments: no Ri inoculation and no biochar addition (control, CK), biochar addition alone (BC), Rhizophagus irregularis inoculation alone (Ri), and their combination (RB). The aim was to investigate the effects of these treatments on the biomass, root morphology, and soil mechanical properties of switchgrass under saline-alkali stress. The results showed that compared to the CK treatment, the RB treatment significantly increased the root, stem, leaf, and total biomass of switchgrass by 67.55%, 74.76%, 117.31%, and 82.93%, respectively. Among all treatment groups, RB treatment significantly reduced soil bulk density, soil water-soluble sodium ions (Na⁺), soil exchangeable sodium percentage (ESP), and sodium adsorption ratio (SAR), while increasing soil porosity. Furthermore, RB treatment significantly improved infiltration rate and shear strength. Compared to the CK treatment, the stable infiltration rate and shear strength under 400 kPa vertical load increased by 70.69% and 22.5 kPa, respectively. In conclusion, the combination of Ri and biochar has the potential to improve soil mechanical properties and increase the biomass of switchgrass under saline-alkali stress.

Arbuscular mycorrhizal (AM) fungi (phylum Glomeromycota) are obligate symbionts with plants influencing plant health, soil a(biotic) processes, and ecosystem functioning. Despite advancements in molecular techniques, understanding the role of AM fungal communities on a(biotic) processes based on AM fungal taxonomy remains challenging. This review advocates for a standardized trait-based framework to elucidate the life-history traits of AM fungi, focusing on their roles in three dimensions: host plants, soil, and AM fungal ecology. We define morphological, physiological, and genetic key traits, explore their functional roles and propose methodologies for their consistent measurement, enabling cross-study comparisons towards improved predictability of ecological function. We aim for this review to lay the groundwork for establishing a baseline of AM fungal trait responses under varying environmental conditions. Furthermore, we emphasize the need to include underrepresented taxa in research and utilize advances in machine learning and microphotography for data standardization.

Ectomycorrhizae (ECM) and their hyphae may account for up to one-third of forest productivity, but we know little about their patterns of decomposition and recruitment. ECM decomposition rates are governed in part by the identity of the symbiont, while the species that colonize new fine roots are determined by a number of abiotic and biotic filters, including the developmental stage of the root system and hyphal network. Sections of forest floor humus were excised from mature pine stands (severing all roots), replaced and randomly sampled over time. Decomposing ECM and ECM forming on newly growing roots were tracked over 15 months by ITS sequencing. ECM were no longer observed on original roots 13 months post-disturbance, while ECM appeared on new roots after 10 months. Individually, the dominant ECM fell into three categories. 1) Cenococcum geophilum decomposed and recruited slowly, 2) Suillus spraguei and Russula spp. decomposed rapidly but exhibited minimal recruitment during the experiment, and 3) Clavulina coralloides and Lactifluus/Lactarius spp. degraded rapidly but also recruited rapidly onto new roots. Our results indicate that rates of ECM decomposition vary among fungal symbionts, and that root severing appears to shift the ECM community to a slightly earlier successional stage. The lack of recruitment of ECM formed by truly early-stage species is likely due to the low level of soil disturbance, which should be advantageous in the context of forest regeneration.

The quality of green tea is influenced by soil microbes in addition to soil conditions and the Camellia sinensis cultivar. Arbuscular mycorrhizal (AM) fungi can significantly improve soil quality and crop productivity; however, the specific AM fungal groups that affect the catechin quality index (CQI) of green tea are not yet clear. In the present study, rhizosphere soil samples, root samples, and fresh tea leaves from six different Camellia sinensis cultivars in Hunan Province, China, were collected. The taxonomic diversity and community composition of AM fungi in the rhizosphere soil and roots were investigated using high-throughput Illumina amplicon sequencing technology, and the mycorrhizal colonization rate was assessed. The two main AM fungal genera in the Camellia sinensis roots and rhizosphere were Paraglomus and Glomus. A higher catechin quality index (HCQI) is correlated with greater accumulation of Paraglomus in the roots of Camellia sinensis. The tea cultivar and the available phosphorus content in the rhizosphere soil significantly affected the mycorrhizal colonization rate and the composition of the AM fungal community within the roots. The mycorrhizal colonization rate affected the catechin composition, consequently influencing the CQI of green tea. Furthermore, fluctuations in the proportional presence of Paraglomus and Glomus within the roots of Camellia sinensis notably affected the CQI. In summary, increased mycorrhizal colonization and increased prevalence of Paraglomus substantially increase the CQI of green tea. These findings have significant implications for the application of AM fungi in the production of high-quality green tea.

Bacterial composition and functions in the hyphosphere of arbuscular mycorrhizal (AM) fungi are complex because AM fungal hyphae transport carbon compounds from plant photosynthesis which feed bacteria and act as signaling molecules. This function is lost when hyphae separate from roots, a common occurrence in soil. However, the impact of such disturbances on hyphal surface bacteria remains unclear. We used in vitro bi-compartmented Petri plates with carrot roots and the AM fungus Rhizophagus irregularis MUCL 43194, separating root and hyphal compartments. Treatments included hyphae connected to roots (+ AM), no hyphae (-AM), and hyphae cut at different times (C3D and C0D, where C3D indicates hyphae cut 3 days before inoculation and C0D indicates hyphae cut on the day of inoculation) subjected to a bacterial suspension extracted from a field soil. Thirteen bacterial phyla were identified, with Streptomyces, Pseudomonas, Rhodococcus, and Cellulomonas dominating. Hyphae increased bacterial ASV relative abundance, notably enriching Actinobacteria ASVs. After 14 days, α-diversity decreased from -AM to C3D, C0D, and + AM, with fewer Bacteroidetes species in + AM compared to -AM. Root-connected hyphae led to deterministic bacterial assembly, while cut hyphae resulted in stochastic assembly. Our findings show that physical disruption of hyphae significantly affects bacterial diversity and may influence ecological functions.

While most green orchids establish associations with non-ectomycorrhizal rhizoctonias belonging to Ceratobasidiaceae, Tulasnellaceae, and Serendipitaceae, fully mycoheterotrophic orchids-excluding albino mutants-primarily depend on either ectomycorrhizal fungi or saprotrophic non-rhizoctonia fungi. This suggests that non-ectomycorrhizal rhizoctonias may be unable to meet the carbon demands of adult orchids that exhibit a high degree of mycoheterotrophy. To understand the physiological ecology of Disperis neilgherrensis, an orchid species with reduced leaves growing in decaying litter from non-ectomycorrhizal trees, we employed molecular and stable isotope analyses to identify its mycorrhizal partners and ultimate nutritional sources at two populations on Ishigaki Island, Japan. Molecular barcoding techniques revealed that D. neilgherrensis forms exclusive associations with non-ectomycorrhizal Ceratobasidiaceae fungi. The Disperis specimens exhibited δ¹³C and δ¹⁵N isotopic values similar to those found in fully mycoheterotrophic orchids that exploit litter-decaying fungi. Furthermore, the pelotons of D. neilgherrensis showed significantly elevated δ¹³C values similar to saprotrophic non-rhizoctonia fungi. Our findings indicate that D. neilgherrensis primarily obtains its carbon from decaying litter through a specialized relationship with non-ECM Ceratobasidiaceae. Given that saprotrophic Ceratobasidiaceae facilitate nearly fully mycoheterotrophic growth in D. neilgherrensis, at least under warm and humid conditions, it is plausible that other (nearly) fully mycoheterotrophic tropical orchids also meet their carbon requirements through associations with saprotrophic rhizoctonias.

Under drought conditions, arbuscular mycorrhizal (AM) fungi may improve plant performance by facilitating the movement of water through extensive hyphal networks. When these networks interconnect neighboring plants in common mycorrhizal networks (CMNs), CMNs are likely to partition water among many individuals. The consequences of CMN-mediated water movement for plant interactions, however, are largely unknown. We set out to examine CMN-mediated interactions among Andropogon gerardii seedlings in a target-plant pot experiment, with watering (watered or long-term drought) and CMN status (intact or severed) as treatments. Intact CMNs improved the survival of seedlings under drought stress and mediated positive, facilitative plant interactions in both watering treatments. Watering increased mycorrhizal colonization rates and improved P uptake, particularly for large individuals. Under drought conditions, improved access to water most likely benefited neighboring plants interacting across CMNs. CMNs appear to have provided the most limiting resource within each treatment, whether P, water, or both, thereby improving survival and growth. Neighbors near large, photosynthate-fixing target plants likely benefited from their establishment of extensive hyphal networks that could access water and dissolved P within soil micropores. In plant communities, CMNs may be vital during drought, which is expected to increase in frequency, intensity, and length with climate change.

Lead (Pb) is a highly toxic metal and a contaminant of many soils across the world. Some fungi are known to be Pb tolerant, persisting in environments with high Pb levels. Here we investigate Pb tolerance in Suillus brevipes and S. tomentosus, two widespread ectomycorrhizal fungal species in the American West where soil contamination due to mining is common. We conducted in vitro growth assays, exposing previously studied isolates to a range of Pb concentrations. We found S. tomentosus to be more Pb tolerant compared to S. brevipes and that isolates from the two species showed both high and low Pb tolerance. There were no correlations between Pb tolerance and Pb soil concentration, isolate growth rate, or Zn tolerance. Lead tolerance was positively correlated with Cd tolerance in S. tomentosus. Our research contributes for understanding fungal metal tolerance variability and paves the way for future work addressing the mechanisms of Pb tolerance and the potential for using Suillus in the recovery of contaminated sites.