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29 records · Page 2Linked to original sources

Two Bacillus PGPB Strains in Wheat and Soybean: Wheat Growth Promotion Without Detectable Rhizosphere Microbiome Restructuring.

Plant growth-promoting bacteria (PGPB) are increasingly deployed as biofertilizers, yet the link between an inoculant's genomic potential and its realized effect on the plant is rarely assessed within an integrative framework that jointly captures the rhizosphere microbiome, plant phenotype, and strain genome. Two Bacillus strains-B. halotolerans 1453 and B. pumilus 630-were applied to wheat and soybean in a factorial pot experiment (2 strains &#xd7; 2 application methods &#xd7; 3 frequencies + control, 3-4 replicates). Rhizosphere samples (n = 67 after filtering) were profiled by 16S rRNA sequencing with PICRUSt2 functional prediction and compositional validation (Aitchison PERMANOVA, ALDEx2, ANCOM-BC2). The PGPB gene repertoire was characterized by genome mining (481 marker genes, 14 categories). Wheat phenotype (six traits) and soybean height were analyzed with models appropriate for count data (Negative Binomial and binomial GLMs) for treatment-vs.-control comparisons, and with factorial ANOVA for decomposition into main effects and interactions. Crop identity was the dominant factor shaping both microbiome structure and function (PERMANOVA R2 = 14.7% taxonomically and R2 = 7.8% functionally, both p < 0.001), with biologically meaningful taxonomic differences between wheat and soybean; strain, application count and method had no significant effect on community composition (R2 < 4% each), and co-occurrence networks showed no reliable differences between crops once read depth and sample size were controlled for. Despite this neutrality at the microbiome level, inoculation significantly increased wheat spike count (NB-GLM, all 12 treatments vs. control, padj 0.0002-0.031), ear weight, and stem count, with application count the strongest source of variability and a pronounced strain &#xd7; application count. Strain 1453 outperformed 630 in spike count (+23.1%, p = 0.012) and ear weight (+20.4%, p = 0.023); we hypothesize that this may be related to its more complete DNRA pathway (narGHI + nirB-nirD) and biocontrol genes (bacE, srfAA). Strain 630 produced a less pronounced effect than strain 1453 but was subject to smaller fluctuations across replicates (CV &#x2248; 16-21% vs. &#x2248;24-26% for 1453), which may reflect better resilience to environmental fluctuations, possibly due to its confirmed rsbV/rsbW stress-tolerance regulon. Rhizosphere microbiome composition differed clearly by crop (wheat vs. soybean) but showed no detectable response to strain, application method, or application count. Despite this lack of a microbiome signal, inoculation significantly increased wheat spike count and ear weight, with the magnitude and stability of this effect differing by strain. We hypothesize that this strain-dependent difference relates to underlying genomic differences-particularly in nitrogen metabolism (DNRA pathway) and stress-tolerance genes-though this link has not been tested directly and remains a hypothesis for future work.

Triticum↗

Desert-derived Ensifer sp. SA403 enhances potato salt tolerance by reshaping rhizosphere microbiome functions and host responses.

Soil salinization increasingly threatens global food security, and potato (Solanum tuberosum L.), a moderately salt-sensitive crop, is particularly vulnerable to saline soils. Plant growth-promoting rhizobacteria (PGPR) offer a promising strategy to improve crop performance, yet how PGPR interact with native microorganisms to enhance potato salt tolerance remains poorly understood. In this study, we identified a desert-derived PGPR strain, Ensifer sp. SA403, which substantially enhanced potato performance under high salinity across sterile, non-sterile and field conditions. Physiologically, inoculation with SA403 reduced shoot Na&#x207a; accumulation and increased the K&#x207a;/Na&#x207a; ratio; notably, these effects were markedly stronger in non-sterile substrates than under sterile conditions, indicating that SA403-mediated ion homeostasis relies on cooperation with the resident microbiota rather than on the strain acting alone. Metagenomic profiling indicated that SA403 strain reshaped rhizosphere communities, significantly enriching beneficial taxa such as Priestia and Bradyrhizobium, and upregulated functional pathways involved in glutathione and sulfur metabolism. Furthermore, host transcriptomic analyses showed that SA403 modulated plant responses to salt stress, with differentially expressed genes enriched in jasmonic acid signaling, ethanolamine metabolism and amino-acid biosynthesis pathways. Field trials on saline soils confirmed that SA403 significantly increased seedling emergence and tuber weight. Together, our results demonstrate that SA403 functions as a biological mediator that optimizes rhizosphere microecology and coordinates ion balance and host signaling to enhance potato salt tolerance. These findings support the potential of SA403 as a robust PGPR-based tool for sustainable potato production on saline soils.

Rhizosphere↗

The metabolic and anatomical complexity of root microhabitats modulate their interaction with the microbiota.

Plant roots constantly communicate with their microbiota, adapting their anatomy to facilitate microbial colonisation under abiotic stresses. Microbes, in turn, can reshape root anatomy once they establish. However, the mechanisms that coordinate this interplay remain largely unknown. Working with the aquatic plant family Lemnaceae, we reveal that the inherent complexity of root anatomy determines root plasticity in response to microbial colonisation. This microbiota-driven anatomical plasticity enhances plant survival in nutrient-competitive environments. By combining synthetic root models with real roots, we also find that anatomical plasticity is associated with metabolic reprogramming during microbial establishment. Moreover, we identify a plant metabolite, N6,N6,N6-Trimethyl-L-lysine, that regulates anatomical plasticity in response to microbial colonisation. Our work generalizes the importance of microhabitat complexity for microbiome recruitment under challenging environmental conditions.

Plant Roots↗

Microbial partnerships and molecular mechanisms in plant stress physiology for climate-resilient and sustainable farming.

Plant-microbial partnerships and their underlying molecular mechanisms are indispensable, natural drivers of improved nutrient acquisition and stress tolerance in the face of climate-driven environmental challenges. Modern multi-omics tools, when coupled with artificial intelligence and synthetic biology, enable the precise design of targeted bioinoculants and synthetic microbial consortia. Translating these advanced microbiome-based strategies into scalable, field-level agricultural applications provides a sustainable path toward securing global food production while maintaining soil health. Global climate change imposes multifaceted abiotic and biotic stresses on crops, disrupting physiological and molecular processes and threatening agricultural productivity. Plant-associated microbes represent an underexplored yet powerful ally in enhancing crop resilience. This review presents current knowledge of plant-microbe interactions and the molecular mechanisms governing plant stress physiology, with an emphasis on climate-resilient and sustainable farming. Hence, ever-changing environmental cues pose a significant burden on agricultural productivity, and plant-associated microbial communities modulate a cascade of physiological and molecular responses, including production of phytohormones, signaling, regulation of reactive oxygen species homeostasis, and activation of plant immune responses to help plants withstand stress and enhance productivity. Moreover, root exudates, phytohormones, and quorum sensing mediate the central communication networks, facilitating plant-microbe cross talk. Additionally, the advances in OMICs approaches aid in disentangling the molecular underpinnings of these interactions by providing mechanistic insights and potential candidate gene targets for crop improvement and stress resilience. In the post-genomic era, integrating artificial intelligence and big data analysis to optimize microbiome-based strategies for sustainable agriculture is a new frontier for disentangling plant-microbe symbiosis to improve soil health, enhance crop yields, and improve stress tolerance. Thus, by integrating the ecological, physiological, and molecular perspectives, this review highlights the transformative potential of harnessing plant-microbe symbiosis for climate-resilient and sustainable agriculture.

Stress, Physiological↗

Unveiling the mechanism of micro-and-nano plastic phytotoxicity on terrestrial plants: A comprehensive review of omics approaches.

Micro-and-nano plastics (MNPs) are pervasive in terrestrial ecosystems and represent an increasing threat to plant health; however, the mechanisms underlying their phytotoxicity remain inadequately understood. MNPs can infiltrate plants through roots or leaves, causing a range of toxic effects, including inhibiting water and nutrient uptake, reducing seed germination rates, and impeding photosynthesis, resulting in oxidative damage within the plant system. The effects of MNPs are complex and influenced by various factors including size, shape, functional groups, and concentration. Recent advancements in omics technologies such as proteomics, metabolomics, transcriptomics, and microbiomics, coupled with emerging technologies like 4D omics, phenomics, spatial transcriptomics, and single-cell omics, offer unprecedented insight into the physiological, molecular, and cellular responses of terrestrial plants to MNPs exposure. This literature review synthesizes current findings regarding MNPs-induced phytotoxicity, emphasizing alterations in gene expression, protein synthesis, metabolic pathways, and physiological disruptions as revealed through omics analyses. We summarize how MNPs interact with plant cellular structures, disrupt metabolic processes, and induce oxidative stress, ultimately affecting plant growth and productivity. Furthermore, we have identified critical knowledge gaps and proposed future research directions, highlighting the necessity for integrative omics studies to elucidate the complex pathways of MNPs toxicity in terrestrial plants. In conclusion, this review underscores the potential of omics approaches to elucidate the mechanisms of MNPs-phytotoxicity and to develop strategies for mitigating the environmental impact of MNPs on plant health.

Plants↗

Divergent responses of the rhizosphere microbiome to organic amendments sustain cadmium immobilization and low crop Cd accumulation after remediation.

This study integrated a two-stage immobilization-cultivation experiment to evaluate the effects of three immobilization strategies (inorganic, organic, and organo-mineral amendments) and two fertilization modes (mineral fertilizer alone and partial substitution with organic fertilizer) on soil cadmium (Cd) immobilization and plant Cd accumulation. During the immobilization phase, the organo-mineral strategy achieved the highest Cd immobilization efficiency of 69.5%. In the cultivation phase, the use of mineral fertilizer alone led to Cd remobilization, whereas organic substitution maintained or even enhanced immobilization, reducing shoot Cd accumulation in pak choi by up to 58.3%. Notably, the combined organic immobilization and organic substitution treatment (OP) was particularly effective: despite not having the lowest soil available Cd, it achieved the lowest plant Cd accumulation (2.83&#xa0;mg&#xb7;kg-1). Genomic analysis indicated that the OP treatment enriched core metagenome-assembled genomes (MAGs), including MAG8/Pelagerythrobacter, MAG13/Sphingomicrobium, and MAG30/VAYN01, which contained the highest abundances of genes related to extracellular polymeric substance (EPS) synthesis, phosphorus mobilization, and complexation-precipitation, suggesting the potential of these microbes to enhance EPS secretion and phosphate precipitation for rhizospheric Cd interception. This functional potential, along with the measured high EPS content (259.88&#xa0;mg&#xb7;kg-1) and low plant Cd accumulation in the OP group, provides coherent correlative evidence supporting the hypothesis that an "EPS barrier-chemical precipitation" mechanism synergistically reduces Cd migration to root surfaces. Collectively, continuous organic management can maintain soil fertility, enhance Cd immobilization, and promote low-Cd crop production, offering an efficient strategy for the safe utilization of remediated farmland.

Cadmium contamination↗

Predictions of rhizosphere microbiome dynamics with a genome-informed and trait-based energy budget model.

Soil microbiomes are highly diverse, and to improve their representation in biogeochemical models, microbial genome data can be leveraged to infer key functional traits. By integrating genome-inferred traits into a theory-based hierarchical framework, emergent behaviour arising from interactions of individual traits can be predicted. Here we combine theory-driven predictions of substrate uptake kinetics with a genome-informed trait-based dynamic energy budget model to predict emergent life-history traits and trade-offs in soil bacteria. When applied to a plant microbiome system, the model accurately predicted distinct substrate-acquisition strategies that aligned with observations, uncovering resource-dependent trade-offs between microbial growth rate and efficiency. For instance, inherently slower-growing microorganisms, favoured by organic acid exudation at later plant growth stages, exhibited enhanced carbon use efficiency (yield) without sacrificing growth rate (power). This insight has implications for retaining plant root-derived carbon in soils and highlights the power of data-driven, trait-based approaches for improving microbial representation in biogeochemical models.

Rhizosphere↗

Community structure of actively growing bacterial populations in plant pathogen suppressive soil.

The bacterial community in soil was screened by using various molecular approaches for bacterial populations that were activated upon addition of different supplements. Plasmodiophora brassicae spores, chitin, sodium acetate, and cabbage plants were added to activate specific bacterial populations as an aid in screening for novel antagonists to plant pathogens. DNA from growing bacteria was specifically extracted from the soil by bromodeoxyuridine immunocapture. The captured DNA was fingerprinted by terminal restriction fragment length polymorphism (T-RFLP). The composition of the dominant bacterial community was also analyzed directly by T-RFLP and by denaturing gradient gel electrophoresis (DGGE). After chitin addition to the soil, some bacterial populations increased dramatically and became dominant both in the total and in the actively growing community. Some of the emerging bands on DGGE gels from chitin-amended soil were sequenced and found to be similar to known chitin-degrading genera such as Oerskovia, Kitasatospora, and Streptomyces species. Some of these sequences could be matched to specific terminal restriction fragments on the T-RFLP output. After addition of Plasmodiophora spores, an increase in specific Pseudomonads could be observed with Pseudomonas-specific primers for DGGE. These results demonstrate the utility of microbiomics, or a combination of molecular approaches, for investigating the composition of complex microbial communities in soil.

Bacteria↗

Plant-derived and microbial biostimulants in sustainable agriculture: mechanisms, applications, and challenges.

Plant biostimulants have emerged as transformative and sustainable tools for improving crop productivity, resource-use efficiency, and resilience under rapidly intensifying environmental stresses. Unlike conventional agrochemicals, biostimulants function by activating physiological, biochemical, and molecular processes that optimize plant performance without directly supplying nutrients or exerting pesticidal effects. This review comprehensively examines the integrated roles of plant-derived and microbial biostimulants in sustainable agriculture, with particular emphasis on microbial-mediated mechanisms underlying plant stress adaptation and rhizosphere functioning. Plant-derived biostimulants, including seaweed extracts, humic substances, protein hydrolysates, amino acids, and chitosan, enhance nutrient acquisition, root architecture, hormonal regulation, and antioxidant defense systems. More importantly, microbial biostimulants, such as plant growth-promoting rhizobacteria (PGPR), endophytic microorganisms, mycorrhizal fungi, actinomycetes, yeasts, and cyanobacteria, exert multifunctional effects through biological nitrogen fixation, mineral solubilization, phytohormone biosynthesis, volatile signaling, osmolyte accumulation, pathogen suppression, and modulation of stress-responsive genes. These beneficial microorganisms reshape rhizosphere microbial communities, improve nutrient cycling, and enhance plant tolerance to drought, salinity, heat, and heavy metal toxicity. Emerging evidence from genomics, transcriptomics, metabolomics, and microbiome-based investigations has further revealed the molecular networks and signaling pathways governing biostimulant-induced resilience and plant-microbe interactions. Despite their substantial promise, inconsistent field performance, formulation instability, regulatory limitations, and inadequate mechanistic understanding continue to restrict their large-scale adoption. This review highlights recent advances in microbial and plant-derived biostimulants while identifying critical knowledge gaps and future opportunities for precision biostimulant engineering, microbiome manipulation, and climate-resilient crop management. The integration of next generation biostimulant technologies into sustainable agricultural systems may significantly reduce dependence on agrochemicals while improving crop productivity, environmental sustainability, and global food security.

Agriculture↗

Host genetic regulation of xylem-resident Pseudomonas enhances cucumber growth.

BACKGROUND: Although endophytic microorganisms play a critical role in plant growth and stress resilience, the genetic basis underlying host selection of beneficial microbiota-particularly within the xylem-remains poorly understood. Cucumber (Cucumis sativus), as a crop model with a well-developed system for studying vascular biology, offers a valuable system to investigate the host genetic determinants of xylem microbiome assembly. RESULTS: By conducting population-level microbiome profiling across 109 cucumber accessions, we identified a conserved xylem microbiota dominated by Proteobacteria. Within this community, 20 core amplicon sequence variants (ASVs) were consistently present in xylem sap. Genome-wide association mapping identified a host genetic locus, CsXPR1, which encodes a tetratricopeptide repeat protein that regulates the abundance of the dominant xylem-colonized Pseudomonas ASV_4. Colonization patterns of ASV_4 varied across host genotypes and were correlated with CsXPR1 expression levels, suggesting a precision genetic regulation of bacterial entry into vascular tissues. Pseudomonas fulva strain 220, with 97% 16S rRNA gene identity with ASV_4, could colonize in cucumber xylem by inoculation of either roots or leaves. Genome analysis and plate assays revealed the biosynthesis of indole-3-acetic acid (IAA), solubilization of phosphate, and a range of plant beneficial traits in strain 220. Inoculation with strain 220 significantly enhanced growth in cucumber, but only in CsXPR1 haplotype that exhibited high gene expression and higher recruitment capacity of the strain. These benefits included notable increases in plant height (38%), stem diameter (36%), leaf area (61%), fresh and dry weight (51% and 85%, respectively), and a 4.57-fold increase in 4-methyleneglutamine content within the xylem sap. CONCLUSION: Our findings reveal a complete "gene-to-function" pathway where the host gene CsXPR1 mediates a genotype-dependent growth promotion. It achieves this by regulating the xylem colonization of a beneficial bacterium, Pseudomonas fulva, which in turn enhances plant growth by enriching the xylem sap with the key metabolite 4-methyleneglutamine. Video Abstract.

Cucumis sativus↗

Bacterial motility in rhizosphere colonization: mechanisms, constraints, and implications for microbial inoculants.

Although the potential of microbial inoculants for sustainable agriculture and environmental restoration has been widely recognized, their field performance remains highly variable and often unpredictable. Current research and development frameworks for microbial inoculants primarily focus on their plant growth-promoting functions and metabolic traits, often overlooking the ecological processes that determine whether introduced strains can successfully disperse, access, and establish within the rhizosphere. Increasing evidence suggests that successful dispersal and establishment cannot be assumed in the highly heterogeneous conditions of soil systems. Here, we summarize the key mechanisms underlying bacterial motility and discuss its role within the broader framework of microbial dispersal, highlighting how motility-mediated processes contribute to rhizosphere colonization. We propose that bacterial motility represents a key mechanistic determinant of biofertilizer efficacy. Its role extends beyond the ability of inoculant strains to physically reach the rhizosphere, encompassing competitive colonization on the root surface, long-term persistence, and the ability to respond to dynamic root-derived chemical gradients associated with newly developing root tissues. We argue that inoculant motility should be elevated from a passive descriptive trait to a core design parameter that can be systematically incorporated and regulated during the development and optimization of microbial inoculants. We outline a multi-tiered strategic framework for next-generation biofertilizer engineering that integrates strain selection, community design, motility regulation, and deployment strategies, thereby unlocking the full potential of synthetic microbial consortia for sustainable agriculture, ecosystem restoration, and climate change mitigation.

Biofertilizer↗