Plants establish symbiotic relationships with various mycorrhizal fungi, which may represent a crucial mechanism for different modes of nutrient cycling and soil ecological processes. However, our understanding of rhizosphere-specific microbial traits—such as fungal functional guilds and bacterial life-history strategies (copiotrophic vs. oligotrophic)—at the individual mycorrhizal tree species level remains limited. In this study, we examined how N addition (47.5 g N m−2 yr−1) affects bacterial and fungal communities in the rhizosphere of two dominant subtropical tree species: Castanopsis hystrix, an ectomycorrhizal (ECM) tree species, and Phoebe bournei, an arbuscular mycorrhizal (AM) tree species. We used amplicon sequencing and ecological trait-based analyses to conduct this research. Nitrogen enrichment led to a reduction in bacterial α-diversity, favouring copiotrophic Gammaproteobacteria and r-strategists while suppressing oligotrophic groups, such as Acidobacteriia, Alphaproteobacteria, and Acidimicrobiia, along with K-strategists. Furthermore, adding N increased heterogeneity in bacterial β-diversity between mycorrhizal plant types, resulting in divergent shifts in copiotrophic and oligotrophic bacterial groups. This shift amplified community differentiation specific to the mycorrhizal plant type rather than promoting convergence. Fungal responses to N addition varied based on the host mycorrhizal plant type. In AM-associated P. bournei, N addition decreased the relative abundance of symbiotrophic AM fungi and reduced fungal α-diversity. Conversely, in ECM-associated C. hystrix, N addition suppressed both saprotrophic and symbiotrophic ECM fungi while increasing α-diversity, likely due to the growth of pathotrophic taxa. Despite these contrasting responses, N addition homogenised fungal β-diversity across mycorrhizal plant types, reducing differences among mycorrhizal-specific fungal guilds. Structural equation modelling revealed that soil N and P availability were the primary drivers of bacterial community restructuring. In contrast, fungal assemblages were impacted by both soil chemistry and root traits, notably fine root length. These findings highlight that N enrichment disrupts mycorrhizal plant type-specific microbial niche partitioning in subtropical forests, favouring copiotrophic bacteria and separating fungal communities from host identities, a potential mechanism driving ecosystem-level functional changes under elevated N deposition.

Symbiotic nitrogen fixation (SNF) in legume-rhizobia represents a sustainable and eco-friendly alternative to chemical nitrogen fertilizers in agriculture. Identifying key factors involved in nodule senescence, is crucial for enhancing SNF by effectively extending the lifespan of nodules. Here, we reveal that sulfur (S), an essential element for SNF, plays a major regulatory role in the senescence of soybean (Glycine max) nodules. Blocking S input into the symbiosome by knocking out either S transporter genes SULTR2;1 or SULTR3;5, resulted in a significant decrease in glutathione levels. This reduction impairs the capacity for reactive nitrogen species scavenging, thereby accelerating nodule senescence. Notably, reducing reactive nitrogen species (RNS) production in rhizobia or increasing S input in soybean nodules through genetic manipulation, can effectively mitigate high nitrogen-induced nodule senescence. Our findings demonstrate that SULTR-mediated S input is a pivotal step in regulating nodule senescence, and provide insights for developing strategies to enhance SNF in legumes by delaying nodule senescence.

There is an urgent need to develop microbial inoculants that can consistently improve crop performance as part of efforts to implement sustainable agricultural practices and reduce the environmental ....

An exquisite symbiotic relationship between legumes and rhizobia leads to the development of nitrogen-fixing special organelles known as nodules in nitrate-deficient environments, whereas a high level of nitrate in soil negatively regulates the pleiotropic phases of root nodule symbiosis (RNS), including rhizobial infection, nodule organogenesis and leghemoglobin synthesis. Here, we identified a special group of nodule-specific non-symbiotic leghemoglobin genes (AhLghs) in the crack entry legume peanut; however, their functional role and transcriptional regulation remain enigmatic. A comparative transcriptomic analysis revealed that the downregulation of nodule inception (AhNIN) and non-symbiotic leghemoglobin (AhLghs) genes played a pivotal role in the nitrate-mediated inhibition of nodulation in peanut. The knockdown of AhLghs and overexpression of AhLgh1 resulted in lower and higher leghemoglobin content, respectively, corroborating their roles as positive regulators of nitrogen fixation in peanut. On the other hand, knockdown of AhNINs not only inhibited root nodulation but also decreased leghemoglobin content in peanut. Further, the DNA-affinity purification sequencing (DAP-Seq) analysis identified various nodulation genes, including AhLghs, as targets of AhNINs. After validating DNA-protein interaction by EMSA, the transactivation assay revealed that AhNINs can positively regulate AhLgh1 after binding to the NIN RESPONSIVE CIS ELEMENT (NRCE) of its promoter. Our work bridges a critical gap in understanding how nitrate influences non-symbiotic leghemoglobin expression by targeting rhizobia-induced NINs in peanut, and offers a potential model suggesting that the nitrate-NIN-Lgh module might represent a key evolutionary event in fine-tuning root nodulation.

Plants and microbial organisms develop close symbioses that have a significant influence on agricultural productivity and plant health. These 'agricultural engines' have continuously supported balancing global food security from historical times. Against the backdrop of the global challenges faced by modern agriculture, including soil degradation and over-reliance on synthetic inputs, this review examines the intricate relationships within the soil microbiome, and their impact on sustainable crop production. It further investigates the pivotal functions of these partnerships in nutrient cycling, biotic stress suppression, hormone modulation, and stimulating and enhancing the flourishing growth of crops. Highlighting the importance of plant-microbe relationships, this study explores the potential of biological nitrification inhibitors, biocontrol agents, and biofertilizers, specifically, nitrogen-fixing bacteria and phosphorus-solubilizing microbes, to optimize nutrient use efficiency, suppress biotic stress, enhance nutrient availability for crops, and mitigate climate change. Furthermore, challenges related to environmental factors and the commercial adoption of microbial products are also scrutinized. The review concludes by outlining future research directions and envisioning the integration of microbial partnerships into sustainable climate resilience agricultural practices, thereby offering a holistic approach to address current agricultural challenges and pave the way for a more resilient and environmentally friendly food production system. This will help guide cutting-edge microbiome-based solutions, to improve global food production and agricultural resource use efficiency in the years to come.

This study demonstrates that the production of surfactin by B. subtilis R31 needs to be balanced. Excessive surfactin will weaken the colonisation ability and disease control effect of the strain. By...

Arbuscular mycorrhizal (AM) symbiosis develops through successive colonization of root epidermal and cortical cells, culminating in the formation of arbuscules, tree-like intracellular structures that are transient yet essential sites of nutrient exchange. To dissect the cellular and structural complexity of AM establishment in rice roots colonized by Rhizophagus irregularis, we applied dual-species spatial transcriptomics to simultaneously monitor plant and fungal gene transcripts at single-cell resolution. This approach revealed surprising differences in transcriptional activity between fungal structures and showed that morphologically similar arbuscules can be transcriptionally distinct. These findings suggest hidden functional diversity among arbuscules at single-cell resolution. Because arbuscules form and degenerate within only a few days, we further sought to capture translational activities across their life span. We pioneered AM-inducible TRAP-seq (Translating Ribosome Affinity Purification followed by RNA-seq) using stage-specific promoters, enabling cell-type- and stage-resolved profiling in AM symbiosis. This revealed extensive spatiotemporal reprogramming of nutrient transport and signalling, with distinct sets of phosphate, nitrogen, and carbon transporters and regulators induced or repressed at different stages of arbuscule development, suggesting that nutrient exchange is dynamically regulated across the arbuscule life cycle. More broadly, cell wall biosynthesis genes and key defence markers were suppressed during arbuscule formation, whereas at a later stage, defence markers were strongly upregulated, suggesting a host-driven shift towards arbuscule termination. Together, these findings highlight the nuanced and dynamic regulation of AM symbiosis at the cellular level, refining our understanding of how nutrient exchange and fungal development are coordinated in space and time.

• Legume symbiosis with rhizobial nitrogen-fixing bacteria enable them to grow in nitrate-depleted soils. Rhizobial symbioses also induces systemic plant defence against bioagressors. • We investigated how nitrogen-fixing symbiosis (NFS) in the legume Medicago truncatula can prime plant defence against the pea aphid Acyrthosiphon pisum. We analysed metabolite modification both by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) and defence pathway gene expression by qPCR in leaves of both NFS and nitrate-fed (non-inoculated; NI) plants after aphid infestation (Amp). • The accumulation of primary and secondary metabolites was modulated by both NFS and aphid infestation. Sixty two defense-related metabolites such as salicylate, pipecolate, gentisic acid and several soluble sugars were differentially regulated by aphid infestation in both NFS and NI conditions. Nineteen metabolites, including triterpenoid saponins, accumulated specifically in NFS_Amp conditions. Gene expression analysis showed that aphid-infested plants exhibited significantly higher expression of Chalcone isomerase, flavonol synthase, hydroxyisoflavone-O-methyl transferase and Pterocarpan synthase, while D-pinitol dehydrogenase was only significantly induced in NI-infested leaves. • Our data suggest that NFS, in addition to being a plant nitrogen provider, stimulates specific legume defenses upon pest attack and should also be considered as a potential tool in Integrated Pest Management strategies.

Bacteroid inorganic phosphorus (Pi) metabolism in the Rhizobium‐legume symbiosis differs between indeterminate and determinate legume nodules. In contrast to alfalfa bacteroids, bean ( Phaseolus vulgaris ) bacteroids exhibit high levels of alkaline phosphatase (AP), the native reporter enzyme for the bacterial Pi stress response. 14C and 32Pi whole plant labelling techniques were used in conjunction with diagnostic mutants (lacking AP or lacking high affinity Pi transport) to assess the relative importance of the Pi stress response in Rhizobium tropici bacteroids during symbiosis. The AP‐ mutant was not defective for symbiosis and did not differ from wildtype bacteroids for Pi acquisition. 14C‐CO2 feeding to host plants revealed 14C‐carbon uptake and accumulation in AP‐ mutant bacteroids, and their nodules were increased relative to wildtype bacteroids, implying that organo‐P compounds may account for meaningful levels of carbon exchange between symbionts. 32Pi tracer experiments implied that the high affinity transporter is important to bacteroid Pi acquisition and symbiotic performance in determinate nodules, but that the symbiosome Pi concentration does not meet the capacity of the high affinity transporter. 32P tracer work also illustrated that Pi taken up into the nodule does not remain in the nodule, but rather is redistributed to the host.

Plant cells constantly monitor both their surroundings and internal state, enabling dynamic responses to developmental and environmental cues. Central to this sensing capacity are membrane-bound receptor kinases (RKs), one of the largest and most functionally diverse protein families in plants. RKs detect a broad spectrum of signals, including microbial molecules, endogenous ligands, and changes in cellular status. They share a conserved modular architecture: an extracellular domain for signal perception, a single transmembrane domain, and a conserved cytoplasmic kinase domain that initiates intracellular signalling. Although structurally analogous to their animal counterparts, plant RKs evolved independently [1,2]. Their functional diversity stems primarily from their extracellular domains, with over 20 distinct structural classes described to date [1–3]. The repertoire of RKs expressed in a given cell type varies, as some RKs are ubiquitously expressed across tissues, while others are restricted to specific organs or developmental contexts [4].

The CLAVATA signaling pathway regulates plant development and plant–environment interactions. CLAVATA signaling consists of mobile, cell-type or environment-specific CLAVATA3/ESR-related (CLE) peptides, which are perceived by a receptor complex consisting of leucine-rich repeat receptor-like kinases such as CLAVATA1 and receptor-like proteins such as CLAVATA2, which often functions with the pseudokinase CORYNE (CRN). CLAVATA signaling has been extensively studied in various plant species for its developmental role in meristem maintenance. In addition, CLAVATA signaling was implicated in plant–microbe interactions, including root nodule symbiosis and plant interactions with mutualistic arbuscular mycorrhizal (AM) fungi. However, knowledge on AM symbiosis regulation by CLAVATA signaling is limited. Here, we report a dual role for Medicago truncatula CRN in development and plant–microbe interactions. In shoots, MtCRN modulates inflorescence meristem branching. In roots, the MtCRN promoter is active in vascular tissues and meristematic regions. In addition, MtCRN expression is activated in cortex cells colonized by AM fungi and negatively regulates root interactions with these microbes in a nitrogen-dependent manner; negative AM symbiosis regulation by CRN was also observed in the monocot Zea mays, suggesting this function is conserved across plant clades. We further report that MtCRN functions partially independently of the AM autoregulation signal MtCLE53. Transcriptomic data revealed that M. truncatula crn roots display signs of perturbed nutrient, symbiosis, and stress signaling, suggesting that MtCRN plays various roles in plant development and interactions with the environment.

The extensive use of synthetic nitrogen fertilizers has sustained global food production for more than a century but at high environmental and energetic costs. Improving ni-trogen use efficiency (NUE) has therefore become a key objective to maintain produc-tivity while reducing the ecological footprint of agriculture. This review synthesizes current knowledge on the biological foundations of NUE enhancement, focusing on the role of microbial biofertilizers and biostimulants. The main mechanisms through which plant-associated microorganisms contribute to nitrogen acquisition and assimi-lation are analyzed. In parallel, advances in genomics, biotechnology, and formulation science are highlighted as major drivers for the development of next-generation mi-crobial consortia and bio-based products. Particular attention is given to the current landscape of commercial biofertilizers and biostimulants, summarizing the principal nitrogen-fixing and plant growth–promoting products available on the market and their agronomic performance. Moreover, major implementation challenges are dis-cussed, including formulation stability and variability in field results. Overall, this re-view provides an integrated perspective on how biological innovations, market evolu-tion, and agronomic optimization can jointly contribute to more sustainable nitrogen management and reduce dependence on synthetic fertilizers in modern agriculture.

Crop domestication has revolutionized food production but increased agriculture’s reliance on fertilizers and pesticides. We investigate differences in the rhizosphere microbiome functions of wild and domesticated rice, focusing on nitrogen (N) cycling genes. Shotgun metagenomics and real-time PCR reveal a higher abundance of N-fixing genes in the wild rice rhizosphere microbiomes. Validation through transplanting rhizosphere microbiome suspensions shows the highest nitrogenase activity in soils with wild rice suspensions, regardless of planted rice type. Domesticated rice, however, exhibits an increased number of genes associated with nitrous oxide (N2O) production. Measurements of N2O emissions in soils with wild and domesticated rice are significantly higher in soil with domesticated rice compared to wild rice. Comparative root metabolomics between wild and domesticated rice further show that wild rice root exudates positively correlate with the frequency and abundance of microbial N-fixing genes, as indicated by metagenomic and qPCR, respectively. To confirm, we add wild and domesticated rice root metabolites to black soil, and qPCR shows that wild rice exudates maximize microbial N-fixing gene abundances and nitrogenase activity. Collectively, these findings suggest that rice domestication negatively impacts N-fixing bacteria and enriches bacteria that produce the greenhouse gas N2O, highlighting the environmental trade-offs associated with crop domestication.

Bacterial genome evolution is characterized by gains, losses, and rearrangements of functional genetic segments. The extent to which large-scale genomic alterations influence genotype-phenotype relationships has not been investigated in a high-throughput manner. In the symbiotic soil bacterium Sinorhizobium meliloti, the genome is composed of a chromosome and two large extrachromosomal replicons (pSymA and pSymB, which together constitute 45% of the genome). Massively parallel transposon insertion sequencing (Tn-seq) was employed to evaluate the contributions of chromosomal genes to growth fitness in both the presence and absence of these extrachromosomal replicons. Ten percent of chromosomal genes from diverse functional categories are shown to genetically interact with pSymA and pSymB. These results demonstrate the pervasive robustness provided by the extrachromosomal replicons, which is further supported by constraint-based metabolic modeling. A comprehensive picture of core S. meliloti metabolism was generated through a Tn-seq-guided in silico metabolic network reconstruction, producing a core network encompassing 726 genes. This integrated approach facilitated functional assignments for previously uncharacterized genes, while also revealing that Tn-seq alone missed over a quarter of wild-type metabolism. This work highlights the many functional dependencies and epistatic relationships that may arise between bacterial replicons and across a genome, while also demonstrating how Tn-seq and metabolic modeling can be used together to yield insights not obtainable by either method alone.

Receptor signalling determines cellular responses and is crucial for defining specific biological outcomes. In legume root cells, highly similar and structurally conserved chitin and Nod factor receptor kinases activate immune or symbiotic pathways, respectively, when chitinous ligands are perceived1. Here we show that specific amino acid residues in the intracellular part of the Nod factor receptor NFR1 control signalling specificity and enable the distinction of immune and symbiotic responses. Functional investigation of CERK6, NFR1 and receptor variants thereof revealed a conserved motif that we term Symbiosis Determinant 1 in the juxtamembrane region of the kinase domain, which is key for symbiotic signalling. We show that two residues in Symbiosis Determinant 1 are indispensable hallmarks of NFR1-type receptors and are sufficient to convert Lotus CERK6 and barley RLK4 kinase outputs to enable symbiotic signalling in Lotus japonicus.

WrtF is a glycosyltransferase that incorporates fucose residues into O-polysaccharide, resulting in a relatively hydrophobic O-polysaccharide that helps host plants recognize these bacteria as commensals. This enzyme belongs to a different fold family than previously characterized fucosyltransferases and, unusually, operates without assistance from either metal cations or positively charged amino acid side chains. We also show that the protein stably binds GDP-fucose in a conformation that is incompatible with acceptor binding and catalysis, implying that the enzyme must reposition the substrate prior to turnover. The observed binding mode is specific to fucose and may help minimize the misincorporation of off-target sugars. These findings expand our knowledge of the range of substrate recognition and catalytic strategies glycosyltransferases can use.

Hybrid vigor, commonly harnessed in maize breeding to boost productivity and stress resistance, is largely attributed to genetic factors. However, recent studies suggest that environmental influences, particularly the plant microbiome, may play a pivotal role in mediating heterosis expression. This study investigates the impact of the rhizosphere microbiome on maize heterosis by exploring interkingdom interactions between plant transcriptomes and microbial communities. We identify a key link between microbial taxa and plant traits associated with heterosis, with a particular focus on root length, growth vigor and rhizoshealth. Through a combination of microbiome profiling, gene expression analysis, and functional assays, we reveal that hybrid plants may harbor a more beneficial and diverse microbiome, which could enhance traits like root development and stress tolerance. Our findings suggest that the plant microbiome, particularly through specific taxa, plays a correlative role in the manifestation of heterosis, offering new opportunities for optimizing maize breeding strategies. The study underscores the importance of the microbiome in hybrid vigor and suggests that future research into microbiome-assisted breeding could lead to more sustainable and productive maize cultivation, particularly in marginal or stressed environments.

Hybrids account for nearly all commercially planted varieties of maize and many other crop plants because crosses between inbred lines of these species produce first-generation [F1] offspring that greatly outperform their parents. The mechanisms underlying this phenomenon, called heterosis or hybrid vigor, are not well understood despite over a century of intensive research. The leading hypotheses—which focus on quantitative genetic mechanisms (dominance, overdominance, and epistasis) and molecular mechanisms (gene dosage and transcriptional regulation)—have been able to explain some but not all of the observed patterns of heterosis. Abiotic stressors are known to impact the expression of heterosis; however, the potential role of microbes in heterosis has largely been ignored. Here, we show that heterosis of root biomass and other traits in maize is strongly dependent on the belowground microbial environment. We found that, in some cases, inbred lines perform as well by these criteria as their F1 offspring under sterile conditions but that heterosis can be restored by inoculation with a simple community of seven bacterial strains. We observed the same pattern for seedlings inoculated with autoclaved versus live soil slurries in a growth chamber and for plants grown in steamed or fumigated versus untreated soil in the field. In a different field site, however, soil steaming increased rather than decreased heterosis, indicating that the direction of the effect depends on community composition, environment, or both. Together, our results demonstrate an ecological phenomenon whereby soil microbes differentially impact the early growth of inbred and hybrid maize.

Legumes are crucial crops in agriculture due to their unique ability to fix atmospheric nitrogen and their role in nutrient cycling, soil fertility, animal feed, and global food security. Despite their ecological and economic significance, legume production faces serious challenges, including soil nutrient depletion and various biotic and abiotic stresses due to changing climate conditions. Leguminous plants strongly depend on host-associated microbiomes, which alter their response to climate variations. Tremendous advancements in culture-independent techniques have essentially transformed our perspectives of plant-microbiome interactions. Microbiome studies in legumes emphasize the importance of understanding the complex interplay between the host and microbes in promoting plant health and productivity, stress tolerance, and nutrient uptake. Translating this scientific knowledge into promising strategies can help to overcome the critical constraints in legume cultivation and enhance its sustainable production. This chapter discusses the advancement made in legume microbiome research and addresses the pivotal role of microbiome in sustainable legume production.

Background Legumes-rhizobia symbiosis has high specificity regulated by a specific class of genes, such as Rj4. Rj4 encodes a thaumatin-like protein belonging to the PR-5 family that restricts soybean from nodulation with many strains of Bradyrhizobium elkanii. How Rj4, a member of broad-spectrum resistance family, specifically regulates nodulation remains unclear. To uncover the molecular mechanism of Rj4, current study integrated transcriptome and proteome to analyze the downstream regulatory pathways and key genes mediated by Rj4, through investigating the gene expression and protein abundance in the roots of soybean BARC2 (Rj4/Rj4) after 0, 6 and 24 h post inoculation (hpi) with B. elkanii USDA61. Results The results showed that a total of 1660 differentially expressed genes (DEGs) and 2633 differentially abundance proteins (DAPs) were identified, in which resistance-related genes and symbiosis-related genes showed opposite expression trend. The key symbiosis-related genes, such as ENOD55, PUB1, and NFP, were up-regulated at 6 hpi but down-regulated at 24 hpi compared with control group. Conversely, the expression of most plant immunity related genes exhibited an initial decrease at 6 hpi followed by an increase at 24 hpi, suggested Rj4 restricted host plant from nodulation in early process through induction of plant immunity related genes and pathways. The key genes involved in plant immunity included pattern-triggered immunity (PTI)-related genes, such as pattern recognition receptors FLS2 and EFR, mitogen-activated protein kinases (MAPK) signaling pathway MPKs, calcium ion related genes CNGCs, CaMCML, and ROS related genes RBOH, as well as effector-triggered immunity (ETI) related resistance (R) genes RPM1 and Ptis, plant hormone signal transduction related genes JAZ and TGA, and flavonoid and isoflavonoid biosynthesis gene Cyps. We validated 8 DEGs via qRT-PCR, showing consistent trends with RNA-Seq (Spearman r > 0.9). Conclusions These findings provide new insights into how plant immunity inhibits legume-rhizobial symbiosis in the Rj4-mediated regulatory network, and provide key candidate genes to study legume-rhizobial nodulation specificity for future research.

Background: Arbuscular mycorrhizal fungi (AMF) form a crucial symbiosis with most land plants, including maize (Zea mays L.), enhancing nutrient uptake in exchange for plant-derived carbon. The SWEET (Sugars Will Eventually be Exported Transporters) family of proteins are key mediators of sugar flux, but their specific roles in regulating carbon partitioning during maize-AMF symbiosis and the downstream effects on sugar accumulation in sink tissues are not well understood. Methods: We conducted a greenhouse experiment to investigate the effects of inoculating maize with the AMF species Funneliformis mosseae. We compared inoculated (AM) and non-inoculated (NM) plants, measuring mycorrhizal colonization, plant growth parameters, photosynthetic efficiency, and soluble sugar (sucrose, glucose, fructose) concentrations in roots, leaves, and kernels. The expression levels of core ZmSWEET genes in root and leaf tissues were quantified using quantitative real-time PCR (qRT-PCR). Results: AMF inoculation led to successful root colonization (~55%) and significantly increased plant biomass, and net photosynthetic rates compared to NM controls. Sugar concentrations were significantly elevated in the leaves and kernels of AM plants. In mycorrhizal roots, the expression of putative symbiosis-related genes ZmSWEET1b and ZmSWEET4c was upregulated by 4.2- and 3.5-fold, respectively. Critically, in the leaves of AM plants, the expression of key phloem-loading and sink-related genes, ZmSWEET11 and ZmSWEET13a, was also significantly enhanced by 2.8- and 3.1-fold, respectively. Conclusion: Our findings demonstrate that AMF symbiosis orchestrates a sophisticated, dual regulation of the ZmSWEET gene family in maize. It localizes specific ZmSWEETs to the root-fungus interface to facilitate carbon delivery to the symbiont, while systemically upregulating different ZmSWEETs in source leaves. This systemic reprogramming enhances sugar transport efficiency throughout the plant, leading to increased sugar accumulation in kernels. This work elucidates a key molecular mechanism by which AMF can improve both the growth and nutritional quality of maize.

SHORT INTERNODES (SHI)-related sequence (SRS) proteins are plant-specific transcription factors that modulate hormone biosynthesis and signalling. Their contribution to legume–rhizobium symbiosis, however, remains largely unexplored. Phylogenetic and collinearity analyses of legume SRS genes classified 12 subclasses and revealed soybean's evolutionary relationships, including large-scale gene duplication. GmSRS14 was specifically highly expressed in root nodules and localised in the nucleus only. Exogenous IAA modulates its expression at low concentrations (1 μM), while high concentrations (100 μM) decrease nodule expression. All ABA concentrations tested (10, 20 and 50 μM) inhibited nodule growth, nitrogenase activity and GmSRS14 expression. Functional validation via hairy root transformation demonstrated GmSRS14 overexpression (GmSRS14-OE) increased nodule number, weight, and nitrogenase activity, while GmSRS14 silencing (GmSRS14-RNAi) suppressed nodulation. This study provides a new idea for breeding soybean varieties with high efficiency of nitrogen fixation.

This study investigated the effects of different tillage practices (conventional tillage, no-tillage, stover dislocation, and deep tillage) on endophytic and rhizospheric microbial communities in a 9-year maize stover returning experiment in Inner Mongolia using Illumina MiSeq sequencing. Results showed that tillage practices significantly impacted microbial community composition, functional guilds, and interaction networks, with effects varying across plant growth stages. No-tillage (NT) increased denitrifying bacteria and plant pathogens, while stover dislocation (SD) and deep tillage (DT) enhanced nitrogen-fixing bacteria. Network analysis indicated that high-intensity tillage (SD and DT) improved microbial community stability, but DT also stabilized harmful microorganisms. Overall, SD was deemed the most suitable method. Future research should focus on long-term impacts and integrate more ecosystem health indicators for comprehensive evaluation.