Despite the essential role of micronutrients in plant metabolic processes and carbon cycle, the mechanisms by which micronutrients regulate plant community traits remain poorly understood. Here, we used a long-term experiment to explore the potential mechanisms of plant community micronutrients and traits along a precipitation gradient. Our results showed that plants shifted toward lateral growth and asexual reproduction over time. From 1985 to 2022, the plant community Fe content increased by 18.8% in the north but declined by 25.2% in the south of the typical steppe. Furthermore, plant community growth and reproduction were sensitive to both micronutrient contents and uptake efficiencies in the north of the typical steppe. While plant community Mn and Zn contents enhanced growth longitudinally, Zn and Fe uptake efficiencies hindered sexual reproduction. Furthermore, soil moisture and GDP per capita were the key drivers of micronutrient variation in the north and south of the typical steppe, respectively. Precipitation fluctuations primarily regulated community traits across all sites. In the arid site, micronutrient-driven shifts in reproduction stabilized the soil carbon stock by balancing biomass allocation. These findings can help us to better understand the coupling of plant micronutrients, traits, and soil carbon stocks, thereby providing the basis for a scientific grassland conservation strategy under global change scenarios.

A major bottleneck in plant biotechnology is the inefficient and genotype-dependent regeneration of callus, which severely limits genetic transformation and functional studies across many species. This barrier is acutely exemplified in the study of beneficial plant-microbe interactions, such as the Epichloë –grass symbiosis—a system conferring remarkable stress tolerance to its host but hindered by a lack of efficient genetic tools. To address this, we established a chromosome-scale genome for an Epichloë native host grass Achnatherum inebrians . We discovered that the expression dynamics of evolutionarily conserved cell pluripotency regulators (CPRs) including ARF5/7/19 , BBM , WUS/WOX5 and CUC1/2 serve as a precise molecular predictor for callus regenerative capacity, revealing that pluripotency is dynamic and peaks within a narrow, definable time window. Harnessing this predictable window enabled the development of a highly efficient transformation system for A. inebrians (49.4% efficiency). Crucially, this CPR-based strategy proved generalizable: applied to wheat and the legume sainfoin, it pinpointed species-specific optimal regeneration windows, boosting shoot regeneration rates to 65.7% and 87.5%, respectively. Collectively, our work provides an integrated research system and a rational design principle that removes a key barrier to uncovering molecular mechanisms in plant systems, particularly the Epichloë –enhanced stress tolerance symbiosis. ### Competing Interest Statement The authors have declared no competing interest. National Natural Science Foundation of China, 32300241, 32441036

The response of plant fungal diseases to nitrogen (N) and phosphorus (P) addition is crucial for ecosystem stability, yet the functional group-specific mechanisms and interannual dynamics remain unclear. We conducted a three-year N and P factorial experiment in a typical alpine meadow. We found that nutrient-pathogen interactions are highly functional group-specific. N addition directly increased forb pathogen load, whereas P addition indirectly suppressed it by enhancing plant diversity. Conversely, grass pathogen loads were synergistically promoted by both N and P, while legume and sedge diseases responded only to N. Furthermore, interannual climate variability (warm-season temperature and humidity) independently drove disease dynamics exclusively in grasses. Despite these pathogen fluctuations, community-level aboveground biomass was largely maintained through potential compensatory mechanisms. Ultimately, this study demonstrates that nutrient enrichment regulates plant diseases through divergent pathways. We propose that functional group-specific pathogen loads can serve as sensitive ecological indicators for monitoring global change impacts in alpine ecosystems.

BACKGROUND AND AIMS:Soils are reservoirs of key nutrients and enzymes for plant fitness and ecosystem productivity. Epichloë fungal endophytes are well-known to shape plant performance, yet the mechanistic link between Epichloë-mediated changes on plant root genes and root exudates with soil biochemistry is not entirely clear. We studied the effect of the foliar endophyte Epichloë gansuensis (C.J. Li & Nan) on the soil biochemistry and composition/abundance of host root genes and exudates. We hypothesized that Epichloë would affect soil biochemistry, and that these changes would be associated with endophyte-mediated alterations in root genes and exudates. METHODS:Soil samples, root tissues and root exudates were harvested from field plots of Achnatherum inebrians (Hance) Keng plants with and without E. gansuensis endophytes. We measured concentrations/activities of nutrients/enzymes in bulk and rhizosphere soils, together with the composition and expression of root genes and exudates that were determined via high-resolution liquid chromatography-mass spectrometry and RNA-sequencing. KEY RESULTS:Epichloë altered concentrations/activities of several nutrients/enzymes in both soil compartments (e.g. organic carbon, β-glucosidase), with larger effects in the rhizosphere soil than bulk soil. Epichloë also modified the expression of root genes (e.g. AHCY) and exudates (e.g. malate, ethylene), with several of the changes in root exudates aligned with the altered expression of root genes (e.g. high malate abundance was associated with enhanced expression of its biosynthesis genes). Many of the Epichloë-derived changes in soil nutrients and enzyme levels were functionally associated with the release by the host plant of bioactive root exudates affected by the endophyte. CONCLUSIONS:Foliar Epichloë endophytes can shape soil biochemistry, root gene expression and root exudate abundance, and the existence of functional links between soil biochemistry and root exudates in plant-endophyte associations.

Pyrenophora chaetomioides poses a significant threat to oat crops by affecting their above-ground parts and impacting economic yield. This study assessed the toxicity of crude toxins from three regional strains of P. chaetomioides on 10 oat cultivars. The most virulent strain, NM-1, was identified for comprehensive toxin analysis and pathogenic mechanisms. Initially, 15 secondary metabolites were isolated from NM-1 through rice medium fermentation and ethyl acetate extraction, categorized into six classes: long-chain fatty acids, amides, sugars, steroids, phenyl derivatives, and nitrogenous compounds. In vitro leaf tests showed that dimethyl phthalate (DMP) and eutypinic acid (EA) have substantial phytotoxicity to oats, with relative lesion areas of 54.11% and 40.12%, respectively, and also exhibit non-host toxicity to alfalfa and Nicotiana benthamiana. Physiological assessments indicated that DMP increases leaf relative electrical conductivity from 11.08% to 69.00%, disrupting membrane integrity. Ultrastructural observations revealed mitochondrial swelling, disorganized chloroplast lamellae, and abnormal stomata. Transcriptome analysis revealed DMP's significant downregulation of 12 photosensory chlorophyll protein complex genes and altered antioxidant enzyme profiles, triggering ROS bursts and membrane lipid peroxidation, ultimately inducing programmed cell death. These insights into DMP's pathogenic pathway offer a theoretical basis for developing disease-resistant oat varieties and green pest control strategies.

The seasonal forage-livestock imbalance poses a critical challenge to sustainable pastoralism on the Qinghai-Tibetan Plateau (QTP), where excessive livestock numbers and widespread grassland degradation have led to systemic energy deficits and diminished ecosystem functionality. This imbalance exacerbates forage shortages, particularly in winter, threatening both herder livelihoods and ecological stability. To meet rising livestock demands while ensuring long-term pasture resilience, it is essential to replenish forage resource deficits and strengthen coordination mechanisms that enhance system coupling across multiple dimensions. This study developed an integrated multidimensional framework to address these challenges through three key strategies: (1) type coupling, achieved by combination of annual and perennial legumes with grasses to maximize their yield (1D); (2) temporal coupling, optimizing forage availability by combining mowing of cultivated pastures with rotational grazing in natural pastures to ensure sufficient winter supplementary feed (2D); and (3) spatial coupling, improving regional forage distribution by strategically locating production zones and minimizing transport distances across the vast QTP (3D). We identified that the combination of annual/perennial and legume/grass forages in cultivated pastures enhanced type coupling (the degree of coordinated coupling can reach as high as 69.56, 56.85, and 49.66 between the first, second, and third harvests), with optimal configurations maximizing the benefits of winter supplementary feeding (compared to the summer season, its degree of coordinated coupling was approximately 4 points higher). We proposed a feasible strategy for maximizing inter-regional forage coupling by considering the forage deficit on the QTP and the supply resilience of adjacent regions. By synthesizing these approaches into a cross-scale model, this research provided a comprehensive conceptual framework, empirical data, and theoretical foundations for mitigating forage-livestock imbalances and promoting sustainable pastoral systems on the QTP.

The influence of large grassland herbivores on soil macro and mesofauna invertebrate diversity has been extensively studied. However, little is known about how small semi-fossorial herbivores affect this diversity. To address this knowledge gap, we investigated the effects of the plateau pika (Ochotona curzoniae) on soil macro and mesofauna invertebrate diversity in alpine meadows on the Eastern Tibetan Plateau. We integrated data on vegetation community characteristics and soil physical variables to explore the mechanism by which small semi-fossorial herbivores influence soil macro and mesofauna invertebrate communities at different intensities of disturbance by plateau pika. We found that as pika disturbance intensity increased, vegetation cover, height, above-ground biomass, soil moisture, and soil compaction decreased, while below-ground biomass and soil temperature increased. Plant richness, plant diversity, and the diversity and abundance of soil macro and mesofauna invertebrates initially increased with rising disturbance, peaked at light levels of disturbance, and then declined. Whereas plant diversity peaked at moderate disturbance levels. In addition, the diversity and abundance of soil macro and mesofauna herbivores, detritivores and omnivores showed a clear correlation with the disturbance intensity, whereas predator populations remained unaffected. Structural equation modelling showed that pika disturbance enhanced soil macro and mesofauna invertebrate diversity (Shannon-Wiener index) through alterations in vegetation cover. These results suggest that semi-fossorial herbivores play a crucial role in shaping vegetation and soil properties, thereby indirectly affecting the diversity, richness, abundance of soil macro and mesofauna invertebrates. Optimal levels of semi-fossorial herbivore activity appear to be vital for the maintenance of soil macro and mesofauna invertebrate diversity in the alpine meadows of the QTP. We suggest that future management strategies for pikas should shift from traditional large-scale eradication to ecological control based on population density thresholds.

Crotalaria is a genus of the Fabaceae family with agricultural and medicinal value, but to date the genome has not been fully sequenced. Although Crotalaria pallida is widely distributed in tropical and subtropical regions, the degree of genetic diversity and the specific traits influenced by geographic dispersal remain unknown. We here report a high-quality genome assembly of C. pallida with 98.52% coverage which is assembled into 8 chromosomes. C. pallida is closely related to Lupinus angustifolius, with genetic divergence occurring ~42.5-57.4 million years ago (MYA). Re-sequencing of 236 C. pallida accessions revealed a genetic diversity decrease as C. pallida spread from Africa to America and Asia, and from Asia to China and finally to Hainan. Significant divergence was observed in seven traits between non-Hainan and Hainan accessions. Genome-wide association studies identified 73 loci for 18 agronomic traits, 25 of which overlapped with divergent sweeps between non-Hainan accessions and Hainan accessions. Furthermore, the dispersal of C. pallida in Hainan reduced genetic diversity, leading to a divergence in allelic frequencies at four candidate genes (CpPTR, CpMYB, CpRLPK, and CpNADK) associated with plant height. This study reveals the genetic basis of trait divergence driven by geographic dispersal and offers valuable resources for the strategic development of C. pallida breeding.

CONTEXT Grazing systems are critical for global food security but are often implicated in carbon emissions, creating a conflict between production and climate mitigation. This tension is acute in sloping grasslands, where uniform management strategies derived from flat-terrain paradigms fail to address complex biophysical constraints, thereby threatening pastoral livelihoods through resource degradation. Conventional restoration practices often rely on indiscriminate grazing exclusion, neglecting the complex interaction between livestock behavior and landscape topographic gradients. OBJECTIVE This study aims to resolve this land-use conflict by validating the plant-animal-soil carbon pump (PASCP) framework. We determine how grazing re-engineers ecosystem carbon dynamics across topographic gradients, moving beyond the simplistic view of grazing as a linear stressor, to identify specific topographic thresholds that dictate whether a grazed system functions as a carbon sink or source. METHODS Leveraging a long-term experiment established in 2001, we conducted intensive monitoring from 2022 to 2025. We utilized a stratified factorial design with spatial block as a random factor, combining grazing (grazed vs. enclosed), aspect (sunny vs. shade), and slope (0 degrees, 15 degrees, 30 degrees, 45 degrees; with flat plots under both regimes serving as baselines) to quantify 15 carbon fluxes and three key system metrics: net C sink strength, sequestration efficiency, and turnover rate. Non-linear fitting and multivariate machine learning analyses were employed to dissect trade-offs, identify topographic thresholds, and unravel regulatory pathways. RESULTS We demonstrate that grazing fundamentally re-engineers the carbon pump rather than merely diminishing output. Livestock act as dynamic regulators that initiate new pathways, transport C, and amplify turnover. The net outcome is strictly arbitrated by topography. We identify steep, sun-exposed slopes (>30 degrees) as critical thresholds where the ecosystem flips from a sink without grazing to a source with grazing, primarily due to high respiratory and abiotic losses of the animal pump in stressful zones. Crucially, under gentle slopes, managed grazing maintained sink capacity comparable to that of enclosed areas. Modeling reveals that the system balance is driven by grazing-stimulated root carbon input, which offsets consumption losses provided topographic stress is low. SIGNIFICANCE Our findings provide a scientific foundation for moving beyond indiscriminate grazing exclusion towards precision, topographically-aware management. By recognizing the re-engineering role of livestock and aligning grazing restrictions with vulnerable zones, thereby reinforcing natural avoidance behaviors, policymakers can implement targeted interventions to co-optimize carbon stewardship, ecosystem resilience, and livelihoods in complex terrains.

CONTEXT: The stability of grassland pastoral systems holds significant implications for maintaining ecological equilibrium, driving economic development, enhancing social welfare, and adapting to climate change. The inherent seasonal grass-livestock supply-demand imbalance in grassland pastoral systems constitutes a fundamental constraint to sustainability. OBJECTIVE: This ongoing pursuit of alleviating systemic contradictions demonstrates the evolutionary development of ranch management wisdom. This study based on the Qinghai-Tibetan Plateau (QTP), characterized by exceptionally short growing seasons where pronounced grass-livestock conflicts are notably evident. Employing a space-for-time substitution approach, we systematically traced the historical progression from nomadic ranching through rotational grazing to spatiotemporal coupling and contemporary smart ranching, with focused investigation of four critical scenarios. METHOD: First, we elucidated the negative feedback mechanisms governing seasonal rotational grazing systems, quantifying the elastic variation ranges of stocking rates between warm and cold season ranches. These findings underpin our proposed "Moderate Negative Feedback Equilibrium" hypothesis. Second, our analysis of industrial and technological empowerment revealed that spatiotemporal coupling solutions require tailored implementation strategies: localized cultivated grasslands effectively supplement natural ranches during cold seasons (with superior coupling efficacy in spring versus winter), while cross-regional forage transfer from agricultural zones provides additional support. Third, we demonstrated how the digital era revolutionizes ranching operations through enhanced data acquisition, processing, decision-making, and automated control systems-the core components of modern smart ranching. RESULTS AND CONCLUSIONS: Finally, from an agricultural ethics perspective, we envision an ultimate paradigm of intelligent ranch featuring fence-free management, seamless integration of natural and cultivated grasslands, and synergistic coexistence of historical wisdom with data-driven autonomy. This evolutionary framework, anchored in negative feedback mechanisms and supported by preliminary quantitative evidence, establishes a conceptual foundation for advancing deep ranching intelligence and achieving sustainable forage-livestock equilibrium.

The pastoral systems of the Qinghai-Tibetan Plateau face a critical paradox between finite natural grassland capacity and growing regional demands. To resolve this, we developed a multi-scale, progressive accounting framework that integrates three methodological tiers: benchmarking-based structural analysis (natural-tocultivated grassland ratio), supply-demand parametric modeling (livestock forage requirements), and energyflow scenario simulation (gross and digestible energy under weight-loss gradients)-to determine the rational scale for cultivated grassland development. Using 16-year rotational grazing data and 3-year cutting trials, we first established a conservative expansion baseline based on the 10:1 natural-to-cultivated grassland ratio, adjusted for local ecological and social constraints. Second, we quantified cold-season forage requirements for yaks and Tibetan sheep based on long-term intake measurements and combined these with multi-harvest yield data from cultivated grassland trials to calculate the necessary expansion ratio (1.05-2.31-fold). Third, we constructed energy balance models using gross energy (GE) and digestible energy (DE) of forages, coupled with livestock weight-loss scenarios (from 30% to 0%) to assess supplementation needs from an energy metabolism perspective. Results indicate that achieving higher-level balance requires 2.19-8.57-fold expansion based on GE and 2.92-10.75-fold based on DE. All three methods converge to validate the need for multi-fold expansion, leading us to propose a concentric spatial layout with cultivated grasslands centrally supporting natural pastures. This progressive quantitative framework provides both empirical support for scientific grassland management and a theoretical foundation for transitioning pastoralism toward quality-driven growth and future "Smart Ranch" development.

Rapid climate change poses risks to vital ecosystem services, thereby threatening human societies that depend on these services. But how are ecosystem services prioritized by various stakeholders, and how might these differential priorities affect the evaluation of climate change impacts on ecosystem-service multifunctionality (ESMF)? To address these questions, we defined ESMF as the joint supply of multiple services relative to stakeholder demand, and conducted a social survey to obtain quantitative measures of ecosystem service prioritization from diverse stakeholders, such as pastoralists and biodiversity conservation agencies. Integrating these stakeholder-specific weightings with biophysical data from a decade-long climate change experiment, we found that stakeholders differed in their priorities, leading to differences in their evaluation of ESMF responses to climate change. Specifically, while warming and altered precipitation led to a decline in ESMF for groups prioritizing biodiversity conservation, multifunctionality was maintained or even increased for pastoralists, whose priorities focused almost entirely on forage provision. Similarly, warming was predicted to negatively impact the ESMF prioritized by environmental protection and biodiversity conservation agencies. These negative impacts were consistently stronger under dry climate conditions than under wet conditions. This work deepens our understanding of how stakeholder priorities shape the evaluation of climate change impacts on ESMF. This knowledge is essential for encouraging the development of appropriate and sustainable management strategies for local ecosystem services under climate change.

Abstract Grazing is among the most direct and effective strategies for anthropogenic regulation of carbon cycling in global grasslands. Through a 24‐year grazing experiment, we propose a conceptual framework of the “Soil‐Plant‐Livestock Carbon Pump” to elucidate the mechanisms underlying grazing effects on carbon cycling within plant, soil, livestock, and soil‐plant‐livestock system. Our results indicate that although each unit increase in grazing intensity reduced carbon in above‐ground standing biomass and litter by 4.91 and 0.91 g C m −2 yr −1 , respectively, grazing ultimately had a significant positive effect on system carbon balance. Specifically, grazing reconfigured the pathways of plant carbon allocation, soil carbon inputs, and livestock carbon consumption. Further analysis revealed that plant and soil carbon cycling pathways were the key direct factors regulating system carbon balance, while livestock indirectly explained 10.6%–44.9% of the variance. Furthermore, from a holistic system perspective, grazing constrained the system carbon pump efficiency, which in turn negatively regulated the carbon balance, accounting for 32%–61% of the variance. These findings indicate that grazing can regulate system carbon balance through the soil‐plant‐livestock carbon pump. Understanding the operating mechanisms of the system carbon cycle is crucial for developing a dual ecological and economic growth strategy.

Abstract Ongoing human activities and climate change threaten global grasslands, where plant nutrients are essential for ecosystem stability. However, long-term assessments (1985–2022) of above- and below-ground nutrient trade-offs remain limited. Here, we conducted a 37-year study along the precipitation gradient (267–441 mm) to investigate the dynamics and trade-offs of plant carbon (C), nitrogen (N) and phosphorus (P). Our study found that with increasing local precipitation, above-ground C, N and P contents increased, while below-ground C content declined. The long-term response of plant nutrients varied spatially; the drier north (267 mm) and central region (334 mm) showed increased above-ground C but decreased N and P over time, whereas the opposite pattern occurred in the wetter south (441 mm). Additionally, the trade-off values of plant C, N and P stocks increased with local precipitation, and temporal stability of the N and P trade-off values was lowest in the drier north. Finally, precipitation fluctuation, fertilizer input and per capita GDP were identified as the key drivers of plant above- and below-ground nutrient dynamics in the northern, central and southern regions, respectively. With increasing local precipitation, the effect of climate on trade-off values shifts from negative to positive, whereas the effect of human activities shifts from positive to negative. Our findings highlight that the long-term response of plant nutrients is regulated by local precipitation patterns, through which the precipitation gradient has reshaped plant nutrient regulation by shifting the dominant driver from climatic to human activities factors.

Plant-microbe symbioses form a multi-layered system integrating vertically transmitted Epichloë endophytes, arbuscular mycorrhizal fungi (AMF), and the rhizosphere microbiome, with implications for nutrient acquisition and pathogen resistance. Epichloë endophytes are maternally inherited and may exert priority effects that influence subsequent associations with AMF and root microorganisms, ultimately shaping defensive pathways. Here, we manipulated symbiosis of perennial ryegrass (Lolium perenne) with Epichloë sp. LpTG-3 strain AR37 and the AM fungus Acaulospora delicata to examine exudate metabolites and the recruited rhizosphere microbiome in relation to host responses to the pathogen Bipolaris sorokiniana. Dual symbiosis with Epichloë and AMF increased host growth and pathogen resistance through enhanced nutrient uptake, elevated defensive enzyme activities in leaves and rhizosphere, and reduced malondialdehyde concentrations. It also recruited potentially beneficial microorganisms and enriched metabolites negatively associated with disease severity; notably, the metabolite Acetamide 1, which accumulated under dual symbiosis, strongly inhibited the pathogen in vitro. Significant correlations among metabolites, rhizosphere microbial communities, and rhizosphere soil properties revealed coordinated belowground responses under the synergistic regulation of AMF and Epichloë that reduced disease severity. Although both symbionts enhanced host performance, AMF played a stronger role than maternally inherited Epichloë in shaping the rhizosphere processes driving growth and pathogen resistance.

The tripartite interplay among plants, bacteria, and fungal endophytes is crucial for maintaining host plant fitness. However, how Epichloë endophytes influence plant-associated bacterial communities in cool-season grasses, particularly in ecologically important yet understudied species, such as Achnatherum inebrians, remains unclear. Using phylogenetic molecular ecological network analysis, we determined that seed-borne (seed epiphytic) and phyllosphere bacterial communities of Epichloë-infected (EI) A. inebrians exhibited reduced network complexity compared to Epichloë-free (EF) plants. Across all samples, Proteobacteria and Firmicutes dominated the keystone taxa, with Pseudomonas (OTU744 and OTU8264) consistently identified as a hub genus in both seed-borne and phyllosphere networks. Culture-based analysis revealed that endophyte-infected plants had a significantly (P < 0.05) higher relative abundance of Pseudomonas and Bacillus than EF A. inebrians, especially Pseudomonas comprised 13, 35, and 33% of isolates from the seed, leaf, and rhizosphere of A. inebrians, respectively. To capture potential functional diversity, we selected two phylogenetically distant Pseudomonas strains from each of the three ecological niches for further analysis. Inoculation of A. inebrians seedlings with these strains consistently promoted plant growth, enhanced forage quality (total nitrogen content), and improved nutritional value (ether extract). Whole-genome sequencing combined core-genome phylogenetic tree of the six Pseudomonas strains and confirmed that five strains belong to P. atacamensis, whereas Pse19 was P. cucumis. Our findings reveal that Epichloë endophytes modulate bacterial network stability and enrich plant-associated Pseudomonas, which synergistically enhance host performance. Collectively, this study provides a mechanistic framework for manipulating keystone taxa and beneficial isolates to improve grass productivity in grassland agricultural ecosystems.IMPORTANCEAlthough the tripartite interplay between plants, bacteria, and fungal endophytes, such as Epichloë, is recognized as vital for host fitness, the specific mechanisms through which these endophytes shape associated bacterial communities, particularly in ecologically significant grasses, such as Achnatherum inebrians, remain poorly understood. This study provides crucial mechanistic insights by revealing that Epichloë endophytes reconfigure the structure and stability of both seed-borne and phyllosphere bacterial networks in A. inebrians, leading to reduced complexity but enrichment of specific keystone taxa. We identify Pseudomonas as a consistently dominant hub genus across these niches. Notably, functional validation shows that diverse Pseudomonas isolates, representative of those enriched by the endophyte, significantly enhance host plant growth, forage quality, and nutritional value. Our findings reveal a synergistic mechanism where Epichloë endophytes modulate bacterial network stability to favor beneficial Pseudomonas populations, collectively boosting host performance.

Livestock grazing is one of the most important land-use activities in grassland ecosystems, imposing significant impacts on soil community abundance, composition and biodiversity. Soil microbiota, such as microbes and nematodes, are key components of soil micro-food webs and contribute substantially to ecosystem functioning. However, it remains unknown how grazing affects soil microbiota on a global scale. In this study, we conducted a meta-analysis based on 146 published studies encompassing 1560 paired observations across various environments to gain comprehensive insights into the influences of grazing on the abundance and diversity of soil microbes and nematodes. We found that grazing significantly decreased soil microbial biomass, total nematode abundance and the abundance of all nematode trophic groups except for fungal-feeders, particularly in temperate grasslands. Such effects were stronger under continuous, heavy-intensity and long-term grazing than under rotational, light or short-term grazing regimes. Sheep grazing, as opposed to cattle grazing or mixed grazing by both sheep and cattle, reduced the abundance of soil microbes and nematodes. While the overall effects of grazing on microbial and nematode diversity are limited, significant declines were observed under heavy, continuous or long-term grazing compared to light, rotational or short-term grazing. Synthesis and applications. Our study indicates that intense (e.g. heavy or continuous) grazing, long-term grazing or grazing by sheep substantially suppresses the abundance and diversity of soil microbes and nematodes. These declines in abundance and diversity would undermine the roles of the soil food webs, thereby impairing ecosystem processes such as organic matter decomposition and nutrient cycling. Therefore, maintaining light to moderate grazing intensity, implementing rotational grazing or extended rest periods, and prioritizing cattle or mixed-livestock grazing are essential to protect soil food webs and maintain grassland ecosystem functions under increasing human pressures.Read the free Plain Language Summary for this article on the journal's .

The phyllosphere microbiome plays crucial roles in plant health, but evidence of 'cry for help' strategy in the face of pathogen attack in the phyllosphere remains limited, particularly for the microbiomes of distinct leaf ecological niches. We investigated whether foliar pathogen anthracnose (Colletotrichum lentis) influenced the assembly and functions of microbiomes in epiphytic and endophytic niches of the phyllosphere of common vetch (Vicia sativa) leaves. We also evaluated synthetic microbial communities (SynComs), including representatives of disease-associated strains, for pathogen protection. Anthracnose mediated the deterministic assembly process of epiphytic bacterial and endophytic fungal communities, and increased the complexity of bacterial co-occurrence networks. Iron competition and antifungal genes were also enriched in the epiphytic bacteria, which produce siderophores and degrade fungal cell walls to counteract pathogens. SynComs of beneficial epiphytic bacteria partially protect hosts by regulating bacterial interactions and inducing host immune responses. These findings suggest that disease drives the deterministic assembly of distinct phyllosphere microbiomes, their diversity and their function. Moreover, SynComs from the epiphytic niche can confer host plant disease resistance.

Plants assemble beneficial rhizosphere microbiomes through a ‘cry for help’ mechanism upon pathogen or insect herbivore attack. The arbuscular mycorrhizal fungi (AMF) can influence the composition of microbial communities in the plant rhizosphere. However, their impacts on the rhizosphere microbiome in response to co‐attacks of pathogens and insect herbivores remain unknown. In this study, a mesocosm of alfalfa, Rhizophagus intraradices , Phoma medicaginis and Acyrthosiphon pisum was used to elucidate how AMF alter the plant rhizosphere microbiome and its responses to multiple biotic stresses. The AMF significantly increased the activity of soil acid phosphatase, urease and β‐glucosidase, causing an enhanced absorption of soil phosphorus by plants. The soil enzymes were also significantly and positively correlated with plant shoot properties, including polyphenol oxidase and peroxidase, salicylic acid (SA) and trypsin inhibitor (TI). Although all the AMF, P. medicaginis and aphids altered the rhizosphere microbiome of alfalfa, the AMF recruited beneficial microorganisms in the alfalfa rhizosphere in response to pathogens and aphid attacks. The multi‐interaction also increased the complexity and stability of the rhizosphere microbial network. Additionally, there is a significant correlation between soil enzyme activity, nitrate nitrogen, TI, SA, biomass, disease severity and the rhizosphere microbiome. Therefore, the AMF improves plant defence and soil biochemistry profiles and assists alfalfa in assembling beneficial rhizosphere microbiomes in response to P. medicaginis and aphid attacks. These findings are vital for understanding the interactions between transboundary species in above‐ and below‐ground systems altered by AMF in natural ecosystems. Read the free Plain Language Summary for this article on the Journal blog.

Enhancing alfalfa seed yield is essential for its comprehensive utilization in the forage, ecological, energy, and food sectors. Optimal irrigation and nutrient management are widely acknowledged as key factors in the arid and semiarid regions. However, the synergistic effects of drip irrigation and micronutrient application, particularly boron, on alfalfa seed production in these areas remain insufficiently understood. To address this gap, we conducted a three-year field experiment to investigate the impact of four irrigation frequencies (2, 3, 4, and 5 times, with 50 mm per application) and four boron concentrations (0, 0.3 %, 0.6 % and 0.9 %) on seed yield, water use efficiency (WUE), and economic benefits in alfalfa. Our results revealed a negative parabolic relationship between seed yield and both irrigation amount and boron concentration. The highest seed yields were achieved with three irrigations (150 mm) combined with a 0.6 % boron application, except for the year of 2021. In 2022and 2023, this optimal treatment resulted in seed yields of 931.28 kg/hm2 and 983.98 kg/hm2, representing a 3.22-fold and 2.08-fold increase compared to the control, respectively. This treatment also produced the highest WUE, with an average value of 2.31 kg/hm2/mm from 2021 to 2023, reflecting a 2.92-fold increase over the control. Furthermore, seed yield exhibited a strong positive correlation with all key yield components (P < 0.001). The structural equation model identified the number of reproductive branches per plant as the most significant contributor to seed yield. These findings provide valuable insights into the effects of irrigation and boron application on alfalfa seed yield and offer practical guidance for optimizing agronomic practices aimed at improving seed production in alfalfa and similar crops.