Search Results (546)

Christmas tree growers are concerned with improving establishment of their plantations. Here, we report the results of a series of on-farm trials conducted with grower-cooperators in the Pacific Northwest (PNW) and Great Lakes (Michigan—MI) regions to determine the efficacy of treatments at planting on improving tree survival and growth in Christmas tree plantations. Cooperating growers planted species that were typical for each region (Fraser fir in the Great Lakes and Douglas-fir and noble fir in the PNW) and managed the plantings using standard cultural practices, aside from test treatments. Test treatments varied between locations and years but included wood chip mulch, shade blocks, an anti-transpirant, biochar, fertilizers, and various root dips including polymer gels, mycorrhizae, and bio-stimulants. Overall, treatments that directly modified the tree environment (i.e., mulch and shade blocks) provided the most consistent benefit to tree survival and growth. In Michigan, mulching increased survival by 5% on non-irrigated farms and increased second-year shoot growth by ~3 cm. In the PNW trials, mulching increased survival of noble fir seedlings more than Douglas-fir seedlings. Installing controlled release fertilizer packets at planting increased initial growth of Douglas-firs. Application of root dips prior to planting did not improve tree survival or growth relative to dipping tree roots in water (control). Based on our results, we conclude that treatments that conserve soil moisture (mulch) or reduce tree water loss (shade blocks) offer the most direct opportunity for growers to improve initial tree survival and growth. Full article

Ectomycorrhizal (ECM) symbiosis is a fundamental mutualism crucial for forest eco-system health. Its establishment is governed by sophisticated molecular dialogue preceding physical colonization. This review synthesizes this pre-colonization crosstalk, beginning with reciprocal signal exchange where root exudates trigger fungal growth, and fungal lipochitooligosaccharides activate host symbiotic programming, often via the common symbiosis pathway. Successful colonization requires fungi to navigate plant immunity. They employ effectors, notably mycorrhiza-induced small secreted proteins (MiSSPs), to suppress defenses, e.g., by stabilizing jasmonate signaling repressors or inhibiting apoplastic proteases, establishing a localized “mycorrhiza-induced resistance.” Concurrent structural adaptations, including fungal hydrophobins, expansins, and cell wall-modifying enzymes like chitin deacetylase, facilitate adhesion and apoplastic penetration. While this sequential model integrates immune suppression with structural remodeling, current understanding is predominantly derived from a limited set of model systems. Significant knowledge gaps persist regarding species-specific determinants in non-model fungi and hosts, the influence of environmental variability and microbiome interactions, and methodological challenges in capturing early signaling in situ. This review’s main contributions are: providing a synthesized sequential model of molecular crosstalk; elucidating the dual fungal strategy of simultaneous immune suppression and structural remodeling; and identifying crucial knowledge gaps regarding non-model systems and species-specific determinants, establishing a research roadmap with implications for forest management and ecosystem sustainability. Full article

The interplay between phosphate (Pi) signaling and defense pathways is crucial for plant fitness, yet its molecular basis, particularly in wheat, remains poorly understood. Here, we functionally characterized the plasma membrane-localized high-affinity phosphate transporter TaPT3-2D and demonstrated its essential roles in Pi uptake, arbuscular mycorrhizal (AM) symbiosis, and fungal disease resistance. Quantitative analyses showed that TaPT3-2D expression was strongly induced by AM colonization (165-fold increase) and by infection with Bipolaris sorokiniana (54-fold increase) and Gaeumannomyces tritici (15-fold increase). In contrast, virus-induced gene silencing (VIGS) of TaPT3-2D reduced Pi uptake and mycorrhizal colonization. Moreover, TaPT3-2D-silenced plants exhibited increased susceptibility to biotrophic, hemibiotrophic, and necrotrophic fungi, accompanied by reduced expression of pathogen-related genes. The simultaneous impairment of Pi uptake, AM symbiosis, and defense responses in silenced plants indicates that TaPT3-2D functionally couples these processes. Functional complementation assays in low-Pi medium further revealed that TaPT3-2D partially rescued defective Pi uptake in mutant MB192 yeast, supporting its role as a high-affinity phosphate transporter. Collectively, these results identify TaPT3-2D as both a key regulator of individual pathways and as a molecular link connecting Pi homeostasis, symbiotic signaling, and disease resistance in wheat. Full article

Heavy metals accumulate in forest soils worldwide, yet their effects on greenhouse gas dynamics remain poorly understood. Mycorrhizal fungi lie at the heart of this issue. These symbiotic organisms regulate carbon and nutrient flow between trees and soil, positioning them to influence fluxes of CO₂, N₂O, and CH₄. However, research on mycorrhizal ecology, metal toxicology, and greenhouse gas biogeochemistry has proceeded largely in isolation. This review bridges these fields through a conceptual framework built on three contamination scenarios and four mechanistic pathways. Our confidence in these mechanisms varies by gas: well-established for CO₂, developing for N₂O, and mostly inferential for CH₄. Critical gaps remain. Studies measuring mycorrhizal communities, metal availability, and gas emissions simultaneously are rare. Comparisons between ectomycorrhizal and arbuscular mycorrhizal systems are virtually absent. This framework establishes a basis for understanding how metal-contaminated forests regulate greenhouse gas exchange and identifies priority areas for future investigation. Full article

Most land plants engage in a mutualistic interaction with arbuscular mycorrhizal fungi (AMF), for which Rhizophagus irregularis is a model species. Like plant pathogenic fungi, AMF genomes encode hundreds of putative effector proteins. However, for only a few, the molecular mechanisms by which they alter the host’s physiology are known. Here, we combined several reverse genetic approaches to unravel the role of the RIRG190 effector protein in arbuscular mycorrhiza (AM) symbiosis. Using multiple heterologous tools, evidence is provided that the RIRG190 effector is secreted and localizes to the plant nucleus. Moreover, by means of yeast two-hybrid (Y2H) and ratiometric bimolecular fluorescence complementation (rBIFC) assays, the data demonstrate that RIRG190 interacts with the protein Something About Silencing (SAS10), known to be involved in rRNA biogenesis in the nucleolus of cortical cells. Our findings suggest that rRNA biogenesis is a key process modulated by AMF, potentially to enhance plant metabolic activity, facilitating cell cycle progression, and to support the establishment of the symbiosis. Full article

Limited phosphorus (P) availability and declining soil biological health are major constraints in intensive rice (Oryza sativa L.)—wheat (Triticum aestivum L.) systems. Rock phosphate–enriched compost (REC), combined with microbial inoculants, offers a sustainable strategy for improving soil biological functioning. A field experiment was conducted under a randomized block design with seven treatments involving different combinations of REC, chemical fertilizers, phosphate-solubilizing bacteria (PSB), and arbuscular mycorrhizal fungi (AMF). Post-harvest soil samples from rice and wheat were analyzed for microbial biomass carbon (MBC), microbial biomass phosphorus (MBP), enzymatic activities, microbial populations, root colonization, yield, and P uptake. The combined application of REC with PSB and AMF significantly enhanced soil biological parameters compared with recommended fertilizer doses. Under the REC + PSB + AMF treatment, dehydrogenase, acid phosphatase, and alkaline phosphatase activities increased by 77.4%, 24.8%, and 18.1%, respectively, while MBC and MBP improved by 51.6% and 106.6%. Bacteria, fungi, and actinomycete population increased by 55.0%, 76.7%, and 82.8%, respectively, as well as mycorrhizal root colonization increased by 18.7%. Grain yield of rice and wheat increased by 16% and 6%, respectively, along with higher P uptake. The integrated use of REC with PSB and AMF improved soil enzymatic activity, microbial biomass, and nutrient acquisition, leading to higher crop productivity. These results indicate that REC combined with PSB and AMF is an effective nutrient management strategy for improving soil biological health, P utilization, and crop productivity in rice–wheat systems. Full article

For successful potato production, maintaining a proper balance of mineral nutrients is crucial, as high yields cannot be achieved in fields lacking essential elements. The exact amount of fertilizer should be determined based on the expected yield, crop nutrient requirements, soil analysis, cultivation technology, and specific growing conditions. N (N) plays a crucial role in potato tuber growth. It is involved in the synthesis of proteins that are stored in the tubers and helps prolong the lifespan of the leaf canopy. On average, potato crops require a N supply of 80–120 kg/ha. Based on several studies, N fertilization significantly increased potato tuber yield, while dry matter content showed a slight decline. This indicates that higher N rates can enhance yield but potentially decrease tuber quality. To achieve high tuber yields while preserving desirable dry matter and starch content, the optimal N rate is approximately 100–120 kg N/ha. Although higher N inputs (>150 kg N/ha) may temporarily boost vegetative growth, they ultimately delay tuber maturation, reduce dry matter and starch accumulation, and increase production costs due to inefficient fertilizer use. Excessive N fertilization accelerates soil degradation and contributes to environmental pollution (soil acidification, NO₃⁻ leaching, NH₃ emissions, NO, N₂O, and NO₂, leading to additional long-term ecological burdens. Therefore, minimizing N losses through sustainable soil management is essential for maintaining both farm profitability and environmental protection. Integrating N fertilization with biofertilizers—such as beneficial bacteria that colonize roots, enhance nutrient uptake, and stimulate root development—can improve yields while reducing reliance on costly synthetic fertilizers. This supports both soil fertility and crop productivity. Full article

This study presents the complete assembly and analysis of the mitochondrial genome (mitogenome) of Medicago lupulina L. var. vulgaris Koch, cultivar-population VIK32, line MlS-1, which forms an effective symbiosis not only with arbuscular mycorrhiza but also with the root nodule bacteria Sinorhizobium meliloti. The assembly, generated using a hybrid sequencing approach, revealed sequences of putative horizontal origin. These include a highly conserved open reading frame (ORF), orf279, encoding a protein structurally homologous to maturase K, yet bearing remote similarity to bacterial reverse transcriptases and CRISPR-associated proteins. We also identified sequences homologous to mitovirus RNA-dependent RNA polymerases and a fragment of the chloroplast 23S ribosomal RNA (rRNA), suggesting historical gene transfers from viruses and plastids. This work establishes a foundation for investigating the role of mitochondrial genome variation in key plant’s phenotypic traits, such as the enhanced responsiveness to arbuscular mycorrhiza observed in this agronomically valuable line. Full article

Essential oil-bearing plants are valued for their aromatic qualities and medicinal value. An example of such a plant is sage (Salvia officinalis L.), one of the most important aromatic herbal plants. Rich in essential oil (EO), sage herb is used in pharmaceutical and cosmetic production and as a spice. This study was conducted to determine the effect of arbuscular mycorrhizal fungi (AMF) on the morphological characteristics, yield, and EO production of sage under different irrigated conditions: 95 ± 5, 75 ± 5, 50 ± 5, and 25 ± 5% field capacity (FC). Maximum herb dry biomass yield and leaf dry biomass yield were obtained at the 95, 75% FC irrigation level, and the highest leaf EO (1.361%) was at 75% FC. The high yield of herb and leaf dry biomass, as well as the highest EO in herb and leaves, was observed with AMF. A group of monoterpenes and sesquiterpenes dominated the EO. The main compounds were 1,8-cineole, α-thujone, β-thujone, camphor, E-caryophyllene, and viridiflorol. The chemical composition of EO has changed under irrigation. Under severe stress (25% FC) and moderate soil moisture (50% FC), the proportion of monoterpene hydrocarbons and oxidized sesquiterpenes was higher than at 75% and 95% FC. The proportion of camphor, α-thujone, and β-thujone was higher with AMF only under severe water stress. With increasing soil moisture, the proportion of α-thujone and β-thujone in EO decreased. A positive correlation was found between EO content and the number of leaves per plant. Our results indicate the prospects for practical application of AMF in combination with the irrigation of sage plants. Full article

With continuous increases in nitrogen (N) deposition in the future, its impacts on terrestrial ecosystems are attracting growing concern. Arbuscular mycorrhiza (AM) fungi play a crucial role in shaping both soil microbial and plant communities. AM fungi play a crucial role in shaping the soil microbial and plant communities, yet their patterns of influence under increased N deposition scenarios remain unclear, particularly in desert ecosystems. Therefore, we conducted a field experiment simulating increased N deposition and AM fungal suppression to assess the effects of increased N deposition and AM fungi on soil microbial communities, employing phospholipid fatty acid (PLFA) biomarker technology in the Gurbantunggut Desert of Xinjiang. We found that increased N deposition promoted soil microbial biomass, including AM fungi, fungi, Actinomycetes (Act), Gram-positive bacteria (G⁺), Gram-negative bacteria (G⁻), and Dark Septate Endophyte (DSE). AM fungal suppression significantly increased the content of soil Act and G⁺. There were clearly and significantly interactive effects of increased N deposition and AM fungi on soil microbial contents. Both increased N deposition and AM fungi caused significant changes in soil microbial community structure. Random forest analysis revealed that soil nitrate N (NO₃⁻-N), Soil Organic Carbon (SOC), and pH were main factors influencing soil microorganisms; soil AM fungi, G⁺, and Act significantly affected plant Shannon diversity; soil G⁻, Act, and fungi posed significant effects on plant community biomass. Finally, the structure equation model results indicated that soil fungi, especially AM fungi, were the main soil microorganisms altering the plant community diversity and biomass under increased N deposition. This study reveals the crucial role of AM fungi in regulating soil microbial responses to increased N deposition, providing experimental evidence for understanding how N deposition affects plant communities through soil microorganisms. Full article

We hypothesized that Tuber melanosporum colonization enhances growth and photosynthetic performance in Corylus avellana seedlings. Forty-eight seedlings were assessed for root colonization (stereomicroscopy, ITS sequencing) and photosynthetic traits (Li-6800F) under short-term disturbed and undisturbed rhizosphere conditions. Mycorrhizal colonization was found in 97.9% of seedlings (47/48). The mean colonization was 33.1% (SD = 16.1), 16.7% of seedlings showed more than 50% colonization per seedling, and 65.0% showed more than 30% colonization per seedling. Colonization declined with root depth and correlated with seedling length (r = 0.371, p = 0.01). In disturbed roots, longer root length predicted higher Gsw (r = 0.60), PhiCO₂ (r = 0.77), and PhiPSII (r = 0.70), while collar diameter negatively affected transpiration (r = −0.60). In undisturbed roots, collar-proximal colonization improved PhiPSII (r = 0.69, p = 0.02). Undisturbed seedlings showed ~2× higher CO₂ assimilation, stomatal conductance, quantum yield, and transpiration. These findings confirm that T. melanosporum enhances seedling physiology, especially under undisturbed conditions. Full article

In this study, we report bioinformatics analysis of the endoglucanase GH9 gene family in tomato (Solanum lycopersicum L.) using the SL5.0 genome, confirming the presence of 19 members that clustered into classes A, B, and C. To explore their potential role in plant–microbe interactions, we determined the transcriptional regulation of 10 SlGH9 gene members in tomato leaves and roots during interactions with the mutualistic root mycorrhizal fungus Rhizophagus irregularis and the foliar pathogen Sclerotinia sclerotiorum. The upregulation of several SlGH9 genes in the leaves of mycorrhizal plants suggests that they are involved in cellulose remodeling and biosynthesis rather than its degradation. This would be consistent with the observed increase in foliar area. On the other hand, downregulation of some SlGH9 genes in leaves of pathogen-infected mycorrhizal plants suggests that these genes may play a role in the enhanced resistance observed by reducing cellulose degradation, thereby maintaining cell wall integrity. The potential involvement of endoglucanase genes in expansive growth (foliar area) and in defense in mycorrhizal and pathogen-infected plants may reflect a growth–defense trade-off. Full article

The soil microbiome is an essential component of agroecosystems. However, managing it remains a challenge due to our limited knowledge of how various environmental factors interact and shape its spatial distribution. This study presents a hierarchical ecological model to explain the assembly of the microbiome in sloping agricultural landscapes. Through a comprehensive analysis of bacterial and fungal communities, as well as the examination of metabolic and phytopathogenic profiles across a topographic gradient, we have demonstrated that topography acts as the main filter, structuring bacterial communities. Land use, on the other hand, serves as a secondary filter, refining fungal functional guilds. Our results suggest that hydrological conditions in floodplains favor the growth of stress-tolerant bacterial communities with low diversity, dominated by Actinomycetota. Fungal communities, on the other hand, are directly influenced by land use. Long-term fallow periods lead to an enrichment of arbuscular mycorrhiza, while agroecosystems shift towards pathogenic and saprotrophic niches. Furthermore, we identify specific topographic positions that may be hotspots for phytopathogenic pressure. These hotspots are linked to certain taxa, such as Ustilaginaceae and Didymellaceae, which may pose a threat to plant health. The derived hierarchical model provides a scientific foundation for topography-aware precision agriculture. It promotes stratified management, prioritizing erosion control and soil restoration on slopes, customizing nutrient inputs in fertile floodplains, and implementing targeted phytosanitary monitoring in identified risk areas. Our research thus offers a practical framework for harnessing soil spatial variability to improve soil health and proactively manage disease risks in agricultural systems. Full article

The use of biostimulants offers a sustainable strategy to improve crop quality. This study assessed the effects of an arbuscular mycorrhizal fungi inoculum (consisting of species Claroideoglomus claroideum, Claroideoglomus etunicatum, Funneliformis geosporum, Funneliformis mosseae and Rhizophagus irregularis) and an 0.5% aqueous extract of Landoltia punctata on the growth and biochemical composition of lettuce (Lactuca sativa L. cv. ‘Dubáček’) under indoor conditions. Four variants were tested: control (C), mycorrhiza (M), L. punctata extract (L), and their combination (M + L), with biometric, physiological, and biochemical parameters evaluated. Simultaneously, the amino acid profile of Landoltia extract was determined, and the degree of plant colonization by mycorrhizal fungi was evaluated. While biostimulant treatments did not affect above-ground biomass, L. punctata extract (L and M + L) significantly raised chlorophyll a (by 15.9% and 16.0%) and chlorophyll b (by 55.5% and 42.8%) compared to the control. The combined treatment (M + L) achieved the highest total phenolic content (254.28 mg/kg). All treated variants significantly reduced leaf nitrate content, with M and M + L being most effective (−35.1% and −33.6%). Amino acid metabolomic analysis showed that the extract is rich in γ-aminobutyric acid, valine, phenylalanine, tryptophan, and other proteinogenic amino acids that may drive its biostimulant effects. Microscopy confirmed successful root colonisation in mycorrhizal variants (58% in M, 42% in M + L). Although the biostimulants did not significantly affect growth, their application is recommended to improve lettuce quality by enhancing photosynthetic pigments and phenolic compounds while reducing nitrate content, indicating their potential for producing safe, higher-quality crops. Full article

Former quarries offer unique opportunities for biodiversity restoration, yet their potential for orchid meadow creation remains underexplored. This study screened soils to study whether these habitats harbour key orchid-compatible fungi essential for orchid colonisation. We conducted comparative analyses of fungal community composition across restored quarry sites using alpha and beta diversity metrics, NMDS ordinations, and regression models linking orchid abundance with fungal diversity. Using soil metabarcoding across four restored sites, the results showed that orchid abundance strongly correlated with fungal diversity, including mycorrhizal families such as Sebacinaceae and Thelephoraceae. The gorge-based site supported the highest orchid density and richest fungal assemblage. These findings demonstrate that former quarries can sustain the fungal networks required for orchid recruitment, providing a foundation for large-scale restoration strategies. Association analysis revealed that orchid abundance, though on a limited scale, is a strong predictor of fungal diversity, indicating that denser orchid populations support richer fungal communities. Despite its limited scale, this study demonstrates that former quarries can provide both the physical conditions and the fungal networks necessary for orchid establishment, offering a practical model for restoring orchid-rich meadows and enhancing biodiversity in former quarries. Full article