Search Results (1,154)

Arbuscular mycorrhizal fungi (AMF) have been widely recognized for their ability to enhance plant drought tolerance. However, the contribution of improved phosphorus (P) nutrition to AMF-mediated drought tolerance in citrus and its relationship with other physiological processes remain unclear. Here, we investigated the physiological mechanisms underlying AMF-mediated drought tolerance in trifoliate orange (Poncirus trifoliata) by combining AMF inoculation with exogenous phosphorus supplementation under drought stress. AMF inoculation markedly alleviated drought-induced growth inhibition, increased plant biomass, enhanced root and rhizosphere phosphatase activities, promoted phosphorus accumulation, and strongly induced the expression of the mycorrhiza-specific phosphate transporter genes PtaPT4 and PtaPT5. Exogenous phosphorus supplementation largely mimicked the beneficial effects of AMF on plant growth and drought tolerance, indicating that enhanced phosphorus acquisition contributes substantially to AMF-mediated drought tolerance in trifoliate orange. However, the combined application of AMF and exogenous phosphorus conferred greater drought tolerance than phosphorus supplementation alone, suggesting that, in addition to improved phosphorus nutrition, AMF further enhances drought adaptation through the regulation of multiple physiological processes. Furthermore, AMF promoted the accumulation of growth-related phytohormones, enhanced antioxidant capacity, and reduced reactive oxygen species (ROS) accumulation, thereby further improving plant drought tolerance. These findings demonstrate that enhanced phosphorus acquisition is an important component of AMF-mediated drought tolerance in trifoliate orange, whereas coordinated regulation of phytohormone homeostasis and antioxidant defense provides additional protection against drought stress. Full article

Acidic soils are widespread in global agroforestry systems and severely constrain crop production through proton stress, aluminum/manganese phytotoxicity, phosphorus fixation, and rhizosphere microbiome reassembly. Rhizosphere diazotrophs can theoretically contribute to plant nitrogen (N) nutrition and stress adaptation. However, their N-fixation efficiency and growth-promoting effects in acidic soils are often highly unstable, limiting the predictability of field applications. This narrative mechanistic review synthesizes and critically interprets evidence on the physicochemical filters governing diazotroph survival in acidic soils, nitrogenase regulation, root-exudate-mediated recruitment, multi-guild microbial interactions, and the conditional design of synthetic microbial communities (SynComs) and inoculant formulations. We further discuss the potential complementary roles of phosphate-solubilizing bacteria (PSB) and arbuscular mycorrhizal fungi (AMF) and propose minimum reporting standards to improve field translatability. The synthesis indicates that effective diazotroph-mediated crop promotion depends on pH buffering, metal detoxification, carbon supply, phosphorus availability, host compatibility, and native microbiome receptivity. The proposed evidence-chain and microbiome-compatibility framework is a conceptual guide for evaluating these linked conditions rather than an empirically validated predictive model. Full article

The mechanisms underlying the symbiotic efficiency of arbuscular mycorrhizal (AM) fungi are actively debated, but comparative metabolomic studies with fungi of contrasting efficiency are scarce. This study aimed to evaluate the influence of effective (Rhizophagus irregularis RCAM00320) and ineffective (Glomus sp. 129.1Te) AM fungal strains on the root metabolome of the responsive Medicago lupulina line MlS-1 at two vegetative and two reproductive stages. Using GC-MS, over 150 metabolites (amino acids, carboxylic and fatty acids, sugars, etc.) were annotated. Effective AM symbiosis was associated with increased levels of phosphoric acid, trehalose, and free fatty acids 16:1, as well as a decreased pool of tricarboxylic acid cycle intermediates (citrate, malate, succinate) and a reduction in γ-aminobutyric acid from the branching stage to fruiting. The comparison revealed that the branching initiation stage, characterized by low arbuscule abundance in ineffective treatment, is likely a main critical metabolic transition determining symbiosis efficiency. Novel metabolic markers of effective AM were identified. Network analysis revealed a divergence of amino acid and fatty acid clusters under effective mycorrhization, whereas under ineffective mycorrhization these clusters were less separated and closely linked in the control. Thus, inoculation with strains of contrasting efficiency generates distinct phenotypes, with effective AM inducing the most pronounced metabolome rearrangements in development. Full article

Ammopiptanthus mongolicus is a rare tertiary relic evergreen broad-leaved shrub that is seriously threatened by Fusarium wilt disease caused by Fusarium verticillioides. Mycorrhiza is a widely occurring symbiotic association of plant roots with arbuscular mycorrhizal fungi. To explore the relationship between wilt disease in A. mongolicus and arbuscular mycorrhiza, fungal communities in the roots and rhizosphere of healthy and diseased plants were analyzed using high-throughput sequencing technology based on specific primer amplicons. Arbuscular mycorrhizal fungal communities in roots were more strongly affected by Fusarium wilt disease than those in the rhizosphere. Wilt disease had no effect on α-diversity indices (Shannon and Simpson) in both the roots and rhizosphere soil, or on the phylogenetic diversity index (Pd) and richness indices (Chao, Ace and Sobs) in rhizosphere soil. However, it had a significant effect on the phylogenetic diversity index (Pd) and richness indices (Chao and Sobs) of arbuscular mycorrhizal fungal communities in the roots. Wilt disease increased the abundance of the genus Sclerocystis and decreased the abundance of Glomus. Arbuscular mycorrhizal fungal communities in diseased plants showed greater co-occurrence network complexity in both rhizosphere soil and roots. In terms of the ecological processes driving arbuscular mycorrhizal fungal community assembly, drift was intensified by wilt disease in both rhizosphere soil and roots. This study revealed the effect of wilt disease on arbuscular mycorrhizal fungal communities in the rhizosphere soil and roots of A. mongolicus. These findings provide important theoretical support and core AMF resources for the ecological prevention and control of A. mongolicus wilt disease. Full article

Peanut (Arachis hypogaea L.) yield depends on biological nitrogen fixation, but the molecular mechanisms underlying the combined effects of arbuscular mycorrhizal fungi (AMF) and calcium fertilizer on nodulation remain unclear. Here, we used integrated transcriptomic and metabolomic analyses to investigate potential mechanisms in peanut roots. Compared with the non-inoculated control, AMF inoculation alone was associated with a 22.1% higher nodule number per plant. The combined application of AMF and CaO showed a 35.9% higher nodulation than AMF alone, and a 30.9% higher AMF colonization rate than AMF alone was also observed. Mechanistically, AMF colonization was associated with enhanced carbon-nitrogen metabolic profiles and up-regulation of phenylpropanoid metabolism-related pathways, suggesting a potential role in providing energy, carbon skeletons, and signaling molecules for nodule formation. Calcium fertilizer correlated with strengthening of the glyoxylate cycle and pentose phosphate pathway, possibly contributing to the energy supply for nodulation. It also affected genes related to protein secretion and lipid metabolism, with observed changes in membrane lipids and transport metabolites, which may enhance symbiotic interface function. This study reveals the multi-level mechanisms through which AMF and calcium fertilizer collectively promote peanut nodulation, providing a systems-level perspective on plant–microbe–nutrient relationships during symbiosis. Our findings offer new insights for sustainable agriculture by reducing chemical nitrogen inputs and promoting nodulation in legumes. Full article

Understanding the ecological adaptability of Pennisetum giganteum (JUJUNCAO) and its long-term effects on rhizosphere microecology is critical for vegetation restoration in fragile ecosystems. In this study, we investigated the soil physicochemical properties and microbial community structure and function in the rhizosphere of P. giganteum cultivated for 1 and 3 years (Y1, Y3), alongside pre-planting soil (Y0), in a dry-hot valley in Chuxiong, Yunnan, China. Following three years of cultivation, the soil total carbon (TC), organic carbon (SOC), total nitrogen (TN), nitrate nitrogen (NO₃⁻-N), total phosphorus (TP), and available phosphorus (AP) showed significant increases of 84.18%, 96.09%, 61.32%, 212.47%, 24.71%, and 22.19%, respectively, whereas the soil pH remained stable. Fungal communities showed significant declines in diversity and richness and a fundamental structural shift as early as one year after planting. In contrast, prokaryotic communities showed a relatively stable structure. Soil carbon and nitrogen variables were the factors most strongly associated with microbial community composition, and long-term cultivation concurrently enriched the arbuscular mycorrhizal fungi Septoglomus and genera containing potential plant pathogens such as Fusarium and Nectria. The relative abundance of Nectria was positively correlated with the soil carbon and nitrogen contents (p < 0.05), suggesting a potential ecological trade-off between beneficial symbiosis and disease risk. Predicted functional pathway composition indicated a shift in microbial metabolism from basal pathways of phospholipid and nucleotide synthesis toward carbon-nitrogen metabolism via PWY-3781 and the glyoxylate shunt, with fungal community turnover more pronounced. Consequently, P. giganteum demonstrates considerable potential for ecological restoration in dry-hot valleys; however, long-term cultivation deserves attention due to potential nitrate loss and the accumulation of taxa containing potential pathogens, with fungal communities serving as sensitive bioindicators of soil health. Full article

Pistachio (Pistacia vera L.) is among the most economically important nut crops worldwide. They are increasingly exposed to the environmental constraints associated with climate change, including drought, salinity, nutritional imbalances, and heightened disease pressure. These stressors compromise plant growth, physiological performance, nutrient acquisition, and orchard productivity, highlighting the need for sustainable strategies to enhance crop resilience. This review critically examines the current knowledge on the functional roles of arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) in pistachio production. Evidence indicates that AMF and PGPR contribute to plant performance through multiple complementary mechanisms, including improved nutrient mobilization and uptake, maintenance of ionic homeostasis, enhancement of water-use efficiency, stimulation of antioxidant defenses, modulation of stress-related signaling pathways, and suppression of phytopathogens. AMF primarily enhance phosphorus acquisition, water relations, and soil structural stability, whereas PGPR contribute to nutrient solubilization, biological control, and induction of plant defense responses. Despite promising experimental results, most studies have been conducted under controlled conditions, limiting the translation of microbial inoculation strategies to commercial orchards in the field. We identified the key knowledge gaps and research priorities required to improve the consistency, scalability, and field validation of microbiome-based approaches for sustainable pistachio production under increasingly challenging environmental conditions. Full article

This study aimed to investigate the effects of arbuscular mycorrhizal fungi (AMF) on the growth and development of common bean (Phaseolus vulgaris L.) and on the microbial environment of the rhizosphere soil. Using the common bean inbred line ‘Jinguan’ as the experimental material, we examined the effects of AMF inoculation on seedling growth and the dynamic changes in rhizosphere microbial communities. The results showed that AMF could establish a stable symbiotic association with common bean roots. By applying seed coating technology to encapsulate AMF around the seeds, and in comparison with the blank control group (CK), the AMF-inoculated plants exhibited altered ratios of fungal to bacterial community structures in the rhizosphere soil. This alteration in root-associated communities subsequently modified plant growth performance, providing a reference for screening beneficial microbial consortia in common bean cultivation. Full article

Arbuscular mycorrhizal fungi (AMF) establish a reciprocal interaction with plant roots, enhancing nutrient acquisition, stress tolerance, and the production of bioactive metabolites. These symbiotic fungi represent a sustainable alternative to chemical fertilizers to improve the quality and yield of medicinal and aromatic plants such as Oregano (Origanum compactum). In this study, we investigated the effects of mycorrhizal inoculation on the chemical composition, nutritional profile, and biological activities of Oregano cultivated under greenhouse conditions. Compared with non-mycorrhizal plants, mycorrhizal-inoculated plants showed approximately 33% higher protein content and 28% higher total sugar content, while lipid concentration decreased slightly by about 7%. Mycorrhizal inoculation also promoted the accumulation of secondary metabolites, resulting in increased concentrations of total polyphenol and flavonoid contents by approximately 33% and 25%, respectively. These compositional changes were associated with markedly enhanced antioxidant capacity, exceeding that of the reference antioxidant, as well as improved antibacterial activity, characterized by larger inhibition zones and lower minimum inhibitory concentrations against tested pathogens. Overall, mycorrhizal fungal inoculation reshaped the chemical composition and the major bioactive compounds of Oregano, thereby enhancing its nutritional and antimicrobial potential. These findings highlight the potential of AMF-based cultivation strategies to improve the phytochemical quality and medicinal potential of Oregano while supporting sustainable agricultural production. Full article

Solanum rostratum is an invasive plant species that poses a serious threat to native ecosystems. In this study, we investigated S. rostratum populations in saline-alkali regions of western Jilin Province to characterize root-associated arbuscular mycorrhizal (AM) fungal diversity and evaluate the effects of AM fungi on plant growth and competitive ability. The results showed that S. rostratum roots were widely colonized by AM fungi, indicating abundant AM fungal resources in its rhizosphere. High-throughput sequencing identified 45 AM fungal species belonging to 13 genera, with Glomus as the dominant genus. A compartmented mesh pot experiment further demonstrated that AM fungal inoculation significantly enhanced the growth and photosynthetic performance of S. rostratum, particularly under saline-alkali soil conditions. When AM fungi were inoculated only in the compartment containing the native plant Setaria viridis, AM fungal colonization was also detected in S. rostratum roots, indicating hyphal connections between neighboring plants through the mesh barrier. Stable isotope analysis further revealed that AM fungi facilitated nitrogen acquisition by S. rostratum and increased ¹⁵N transfer from neighboring S. viridis under common mycorrhizal networks. These findings suggest that abundant AM fungal resources in the rhizosphere contribute to the growth advantage of S. rostratum. By enhancing nutrient acquisition and potentially facilitating nitrogen transfer through mycorrhizal networks, AM fungi may strengthen the competitive ability of this invasive plant under saline-alkali conditions. Full article

Botanical gardens are highly heterogeneous plant systems characterized by high taxonomic diversity, with numerous plant taxa represented within confined areas, and complex ecological interactions that create unique challenges for pest management. Conventional IPM strategies, designed for simplified agroecosystems, often fail to address complex pest pressures in curated environments. Microbial biostimulants have emerged as promising components of sustainable IPM strategies by enhancing plant defense responses, improving stress resilience, and reducing reliance on chemical inputs. This review synthesizes current knowledge on microbial biostimulants, including plant growth-promoting rhizobacteria, arbuscular mycorrhizal fungi and endophytic microorganisms, in modulating plant defense against insect herbivores. These beneficial microbes enhance plant resistance through multiple mechanisms. They activate induced systemic resistance and modulate key phytohormones, including jasmonic acid, salicylic acid, and ethylene. Additionally, they regulate calcium-dependent and reactive oxygen species-mediated defenses. Microbially induced changes in plant secondary metabolites and volatile organic compounds further influence herbivore behavior and trophic interactions. Emphasis is placed on integrating microbial biostimulants into IPM frameworks tailored to botanical gardens. This highlights compatibility with biological control agents and reduced reliance on synthetic pesticides. Despite promising advances, challenges remain, including context-dependent efficacy, host specificity and limited long-term validation. Overall, microbial biostimulants offer a promising tool for enhancing IPM in biodiversity-rich botanical gardens, although further long-term validation is needed to fully assess their sustainability and effectiveness. Full article

In protected cultivation, light intensity, spectral quality, red/far-red ratio, photoperiod and diel fluctuation can alter the belowground biological environment by modifying carbon allocation, root architecture, root exudation, nutrient acquisition, immune tone and rhizosphere physicochemistry. Direct community-level evidence in vegetables remains sparse, but targeted experiments on bacterial colonization, arbuscular mycorrhizal symbiosis, beneficial fungi and root pathogens show that light can condition specific plant–microbe interactions. This review develops a molecular framework for light–root–microbiome interactions in protected vegetable crops and distinguishes direct community evidence, targeted colonization or symbiosis evidence, crop-specific indirect evidence and mechanistic analogues. We synthesize how photoreceptors and PIF-, HY5-, hormone- and immunity-related pathways regulate root niche construction, while also considering direct microbial photoreception. Experimental examples include tomato rhizosphere responses to shading, R:FR-dependent colonization by Serratia plymuthica, phyB–HY5–strigolactone control of tomato mycorrhization, light-intensity effects on lettuce–AMF interactions, spectrum-dependent Trichoderma harzianum colonization and light sensing by Ralstonia pseudosolanacearum. The evidence supports the view that light acts as a conditional regulator whose effects depend on crop genotype, microbial partner, substrate, nutrient status and developmental stage. Progress will require factorial lighting experiments coupled with exudomics, stable-isotope tracing, absolute microbial quantification, isolate genomics, synthetic communities and pathogen-challenge assays. Full article

Phyllosphere microorganisms interact with host plants to regulate growth, promote nutrient uptake and enhance stress tolerance with host specificity, while arbuscular mycorrhizal fungi facilitate plant nutrient absorption and stress adaptation. Current poplar microbial studies mostly focus on hermaphroditic species, with limited research on dioecious poplars. This study selected four poplar species commonly hybridized with Populuscathayana and Populus deltoides in the Xinmin area of Liaoning Province as research subjects: two female plants, DM-9-18 and DX-08-01, and two male plants, 2111 and Qingshan poplar. We performed MiSeq high-throughput sequencing targeting bacterial 16S rRNA, fungal ITS, and arbuscular mycorrhizal fungal (AMF) marker genes from poplar phyllosphere, coupled with chemical quantification of leaf, root and rhizosphere soil, to disentangle clone- and sex-associated divergence in microbial assemblages and their core environmental drivers. No significant gender differences were observed in leaf and rhizosphere nutrient levels and microbial α diversity, whereas male poplars had higher rhizosphere soil nutrients. Male and female poplars genotypes harbored distinct microbial ASVs. The dominant phyllosphere microbes and arbuscular mycorrhizal fungi exhibited gender-specific abundance variations, and nutrient content was the key factor shaping microbial communities. This study clarifies microbial community differences among the four selected hybrid poplar clones. While the experimental design confounds sex with host genotype, the observed patterns provide insights into potential sex-related variations. Our results advance the mechanistic understanding of how dioecious poplar genotype and sexual phenotype jointly filter leaf and root-associated microbial symbionts, with applied implications for hybrid poplar breeding and shelterbelt microbial regulation. Full article

Arbuscular mycorrhizal (AM) fungi are often considered host generalists. Although the host-mediated assembly of AM fungal communities is well documented, its functional significance remains poorly understood, particularly in organic and low-input agroecosystems, where crop–weed interactions may influence the soil AM fungal reservoir. We investigated plant and AM fungal functional traits, mycorrhizal dependency (MD), and root AM communities in three legume crops and five weed species grown in pots with the same indigenous AM fungal inoculum. AM fungal communities were characterized using SSU rRNA gene clone libraries, sequencing, and terminal restriction fragment length polymorphism (T-RFLP) analysis. Of 825 examined clones, 792 were assigned to AM fungi, representing 23 RFLP types. Plant species significantly affected the plant traits, root colonization, spore density, extraradical mycelium density, and MD. PERMANOVA revealed that plant species explained 97.3% of the variation in the AM fungal community structure, although this result should be interpreted cautiously because within-species dispersion may have contributed to the explained variance. RELATE analysis showed a significant association between the AM fungal community structure and plant–AM fungal functional traits. The specific root length, shoot and root N concentrations, AM fungal colonization, and spore abundance best explained community patterns. Legume crops supported greater AM fungal development and positive growth responses, whereas several weeds hosted diverse AM communities without showing biomass benefits. These findings highlight that weed management could indirectly influence AM fungal persistence through host-mediated community assembly, although field validation is required. Full article

Pepper fruits contain diverse primary and secondary metabolites, including ascorbic acid, carotenoids, phenolics, and flavonoids, which contribute to nutritional quality, antioxidant capacity, coloration, and consumer acceptance. Chilaca chili pepper (Capsicum annuum L.) is a Mexican cultivar valued for its distinctive flavor and pungency, representing a valuable resource for studying fruit quality and sustainable crop improvement. This study evaluated the individual and combined effects of arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) on growth, physiological responses, antioxidant activity, and fruit quality traits. Twelve treatments in a 3 × 2 × 2 factorial designs were evaluated for chlorophyll, soluble solids, biomass, APX and LOX activities, and vitamin C and capsaicin contents at three ripening stages (green, mid-red, and red). Enzyme activities were determined spectrophotometrically, and bioactive compounds were quantified from methanolic fruit extracts. Microbial inoculation primarily improved fruit physiological quality rather than vegetative growth. Biomass and growth traits showed no significant differences among treatments (p > 0.05), whereas biochemical responses exhibited distinct ripening-dependent patterns. APX activity, vitamin C, and capsaicin increased from green to mid-red stages and declined at full ripeness. Bacillus sp.-based treatments (T1 and T2) produced a significant transient increase in LOX activity during mid-ripening, while T7 showed a similar but weaker response. AMF progressively enhanced LOX activity and capsaicin accumulation in green fruits. PGPR effects were strain-dependent, with Bacillus sp. promoting early capsaicin accumulation and A. deleyi favoring higher levels during advanced ripening. Overall, AMF and PGPR differentially regulate antioxidant metabolism, vitamin C accumulation, and capsaicinoid biosynthesis while interacting with mineral fertilization to improve fruit quality. These findings support beneficial microorganisms as sustainable tools for enhancing nutrient-use efficiency and fruit nutritional and functional value without replacing mineral fertilization. Full article