Jean-Michel Ané jeanmichelane

Mechanistic insights into bidirectional extracellular electron transfer driving synchronous nitrogen fixation in Klebsiella variicola Electricigens serve as anode catalysts to catalyze nitrogen fixation. At present, only a few electricigens can simultaneously perform both outward and inward extracellular electron transfer (EET) metabolic pathways during the process of biological nitrogen fixation. The mechanism of bidirectional EET coupling in nitrogen-fixing is still not well elucidated. In this study, a nitrogen-fixing bacterial strain Klebsiella variicola C1 that possesses the capacity for bidirectional EET was first reported. Scanning electron microscopy (SEM), three-dimensional fluorescence spectroscopy and cyclic voltammetry (CV) were employed to reveal the differences of biofilms formed at the anode and cathode. Fluorescence-based quantitative PCR and comparative proteomic approaches were used to explore key genes and proteins involve in bidirectional EET pathways and nitrogen fixation. The results showed the outer-membrane lipoprotein carrier proteins seemed to be primarily responsible for facilitating electron transfer from the cell to the anode, whereas pilus proteins may mainly perform electron uptake from the cathode. Additionally, an NAD(P)-dependent oxidoreductase located in the cytoplasm appears to play a critical role in ATP synthesis, which might contribute to efficient nitrogen fixation at the anode. Overall, these results suggested that bidirectional EET for K. variicola C1 led to different nitrogen fixation performance.

Mechanistic insights into bidirectional extracellular electron transfer driving synchronous nitrogen fixation in Klebsiella variicola - ScienceDirect

08.03.2026 15:57 — 👍 0 🔁 0 💬 0 📌 0

Engineering of Azotobacter chroococcum enables potential replacement of synthetic nitrogen fertilizer and mitigation of nitrogen pollutants release under medium-fertility field conditions Engineered free-living diazotrophs with enhanced ammonium excretion have long been proposed as a promising biofertilizer to replace chemical nitrogen fertilizers synthesized via the Haber-Bosch process. Deletion of nifL has been widely used as a strategy to engineer nitrogen-fixing strains with enhanced NH4+ excretion. However, the effects of nifL mutation on the global expression of genes and proteins in nitrogen-fixing strains, as well as their actual environmental effects under field conditions, remain not fully understood. We created an Azotobacter mutant (A4) through deletion of the central nifL gene region without introducing any additional promoters or other genetic modifications. The A4 exhibited excellent ammonium excretion and retained phenotypic stability for four years of subculturing. Transcriptomic and proteomic analyses revealed a significant upregulation of NifA-activated genes and their corresponding nitrogen-fixation proteins in A4 compared to the wild types. The high-level nitrogen fixation supports the ability of A4 to potentially replace the synthetic nitrogen fertilizers while maintaining normal yields in vegetable field cultivation under medium-fertility soil conditions. Notably, A4 application reduced nitrogen pollutant release by 87.4%, compared to conventional fertilization. Inoculation with A4 significantly enhanced the predicted nitrogen fixation-related functions of the rhizosphere microbial community without introducing potential ecological risks. This work offers a stable and field-effective strategy for sustainable agriculture.

Engineering of Azotobacter chroococcum enables potential replacement of synthetic nitrogen fertilizer and mitigation of nitrogen pollutants release under medium-fertility field conditions - Science...

08.03.2026 15:56 — 👍 1 🔁 0 💬 0 📌 0

Soybean genotype determines functional symbiotic outcomes with phylogenetically diverse Bradyrhizobium | Research Square Soybean can meet much of its nitrogen demand through biological nitrogen fixation (BNF). However, yields in sub-Saharan Africa (SSA) remain constrained by nitrogen deficiency and inconsistent responses to rhizobial inoculation. Despite widespread promotion of inoculation, the influence of host genotype on symbiotic effectiveness in African soybean cultivars remains is not well characterized. We assessed nodulation, nitrogen fixation, and growth responses of three widely cultivated Ghanaian soybean cultivars inoculated with ten phylogenetically diverse Bradyrhizobiumstrains under controlled, nitrogen-free conditions. Symbiotic performance was assessed using nodulation traits, acetylene reduction assay, shoot biomass, and relative symbiotic effectiveness (RSE) relative to mineral nitrogen treatment. Symbiotic outcomes were strongly dependent on the host. Two cultivars exhibited high nitrogen fixation and growth with multiple strains, whereas one showed consistently weak fixation and growth despite nodulation, indicating host-imposed post-infection constraints. Nodule weight and nitrogenase activity, but not nodule number, reliably predicted symbiotic benefits. Notably, several non-classical soybean Bradyrhizobium strains performed comparably or better to recognized soybean symbionts when paired with compatible hosts. These results demonstate that host genotype is a key determinant of soybean BNF effectiveness and highlight the need to integrate symbiotic performance traits into breeding and inoculant design for reliable BNF in low-input SSA farming systems.

Not really a novel concept, but an interesting application -> Soybean genotype determines functional symbiotic outcomes with phylogenetically diverse Bradyrhizobium | Research Square

08.03.2026 15:54 — 👍 0 🔁 0 💬 0 📌 0

Rethinking symbiotic nitrogen fixation: Could surplus carbon drive unexpected patterns of resource allocation? Background and Aims The return-on-investment framework suggests that symbiotic nitrogen fixation (SNF) is carbon (C)-expensive and optimized for nitrogen (N) acquisition, implying its downregulation when N is abundant. However, many studies reveal paradoxical findings, with high SNF rates occurring under high N availability, often under conditions of drought, high light intensity, and elevated CO2. Scope Here we propose an alternative framework suggesting that C allocation to SNF is at least partly driven by plants transporting surplus C belowground, rather than being solely explained by N demand or availability. Under conditions like moderate drought, nutrient limitation, high light, or elevated CO2, plants may accumulate surplus C. For instance, moderate drought inhibits leaf growth but maintains photosynthesis, generating surplus C that could stimulate SNF through increased nodule biomass and SNF rates, even with low plant N demand. Conclusions Therefore, plant C availability may be a key factor regulating SNF. Adopting this surplus C perspective could improve ecological models, particularly for plant-microbial interactions under climate change scenarios. We recommend experimental validation involving isotopic tracing of C and N, and monitoring non-structural carbohydrate pools and SNF under conditions that induce C surplus. We suggest that plant surplus C provides a plausible, parsimonious explanation for many observations and should be considered when interpreting unexpected or paradoxical patterns in SNF.

Rethinking symbiotic nitrogen fixation: Could surplus carbon drive unexpected patterns of resource allocation? | Plant and Soil | Springer Nature Link

05.03.2026 22:27 — 👍 0 🔁 0 💬 0 📌 0

Non-nodulating Rhizobium-like ACO-34A fixes nitrogen in pure cultures and has a nif plasmid | Research Square Rhizobia fix nitrogen in plant nodules. Notably, Rhizobium sp. ACO-34A (which could be reclassified as Paenirhizobium), recovered from the rhizosphere of Agave americana, is capable of fixing nitrogen in a defined medium in microaerobic conditions and carries nifHDKENBV genes in a 213 kb plasmid. ACO-34A failed to induce nodules in several leguminous hosts and does not have nod genes. ACO-34A NifH mutant did not fix nitrogen in pure cultures and did not promote stem growth in Lotus japonicum plants as the wild strain did. The plasmid harboring the nif genes contains repABC replication genes, genes for homocitrate synthesis, for toxin-antitoxin production and for plant colonization. Comparative phylogenomic analyses revealed that strain ACO-34A is close to Ciceribacter sichuanensis S101, which was isolated from soybean nodules and should be reclassified. According to ANI, AAI and dDDH parameters, ACO-34A may represent a novel species within the Rhizobiacea family.

Non-nodulating Rhizobium-like ACO-34A fixes nitrogen in pure cultures and has a nif plasmid | Research Square

04.03.2026 19:42 — 👍 2 🔁 0 💬 0 📌 0

The LIN and LINL E3 ligases function redundantly in arbuscular mycorrhizal symbiosis and nodulation of Medicago truncatula LUMPY INFECTION (LIN) is known to direct the polar growth of infection threads during nodulation in Medicago. However, the role of LIN in the arbuscular mycorrhizal (AM) symbiosis has yet to be char...

LIN and its homologs are involved in root nodule and arbuscular mycorrhizal symbioses:
nph.onlinelibrary.wiley.com/doi/full/10....

02.03.2026 21:04 — 👍 4 🔁 0 💬 0 📌 0

Kiva is an easy way to make a real difference in someone's life. Will you join me in helping Lineth in Nandi Hills to pursue their dream? www.kiva.org/invitedby/je...

01.03.2026 18:48 — 👍 0 🔁 0 💬 0 📌 0

Isolation and Genetic Enhancement of Nitrogen-Fixing Rhizobacteria for Promoting Growth in Maize | Preprints.org This study aimed to isolate and characterize nitrogen-fixing bacteria from the maize rhizosphere and evaluate their plant growth-promoting potential to reduce reliance on synthetic fertilizers and enhance soil fertility. Nitrogen-free selective media were used for bacterial isolation, followed by detection of the nifH gene and nitrogenase activity. Phylogenetic identification was conducted via 16S rRNA sequencing. Growth-promoting traits, stress tolerance, and pot-based plant inoculation effects were assessed. Genetic modification of strain GN8811 was performed to improve nitrogen fixation and growth promotion. Seven isolates possessed the nifH gene and nitrogenase activity, including Azotobacter chroococcum GN2001, A. vinelandii GN1202, Azospirillum brasilense GN1004, Kosakonia sacchari GN2003, Klebsiella michiganensis GN8799 and GN8801, and K. quasivariicola GN8811. Furthermore, GN8801 and GN2001 exhibited phosphate solubilization and iron chelation, while GN1004 and GN8811 showed strong IAA production and potassium solubilization. Additionally, GN2003 and GN8811 tolerated high salinity and variable pH. Maize inoculated with GN8811 showed biomass and root enhancement comparable to nitrogen-fertilized controls. The genetically modified GN8811 strain (ΔnifL::nifA) exhibited further improvement in ni-trogen fixation and plant growth, maintaining performance even under high nitrogen conditions. Diverse nitrogen-fixing bacteria were identified from the maize rhizo-sphere, possessing multiple growth-promoting functions and stress tolerance. K. quasivariicola GN8811 demonstrated the best performance, and its genetic enhancement further improved nitrogen fixation efficiency. These findings highlight the potential of combining microbial screening with genetic engineering to develop efficient bioinocu-lants for sustainable maize cultivation. Biological nitrogen fixation by plant-associated bacteria offers a promising route to reduce synthetic nitrogen fertilizer inputs in cere-al-based agroecosystems, yet its reliability is often constrained by environmental stress and nitrogen repression. In this study, we combined systematic isolation of native maize rhizosphere diazotrophs with targeted regulatory engineering of the NifL–NifA system to generate a high-performance nitrogen-fixing strain capable of promoting maize growth even under nitrogen-replete conditions. Our results demonstrate that precise genetic rewiring of indigenous plant-associated bacteria can substantially en-hance nitrogen fixation efficiency and plant growth promotion, highlighting a viable strategy for developing next-generation biofertilizers to support sustainable maize production.

No evidence here that these bacteria give nitrogen to the crop -> Isolation and Genetic Enhancement of Nitrogen-Fixing Rhizobacteria for Promoting Growth in Maize[v1] | Preprints.org

01.03.2026 17:58 — 👍 3 🔁 0 💬 0 📌 0

Phyllosphere and rhizosphere microbiomes empower Nicotiana tobacum complex traits dissection and prediction | bioRxiv Understanding how plant-associated microbiomes interact with host genome variation to influence agronomic traits is essential for advancing microbiome⍰assisted crop improvement. In this study, we characterized the phyllosphere and rhizosphere microbiomes of 164 diverse Nicotiana tabacum accessions using 16S rRNA sequencing and integrated these data with host genomic variation and 22 agronomic traits. The two microbiomes exhibited distinct taxonomic structures, diversity patterns, and predicted metabolic functions. Microbiome genome⍰wide association studies identified extensive host genetic control over microbial abundance, including 49 shared genomic loci that explained nearly half of the heritable variation in both microbiomes. Microbiome⍰wide association studies revealed biologically meaningful associations between specific ASVs and agronomic traits. However, network analysis demonstrated that microbial sub⍰communities, rather than individual taxa, contributed substantially to phenotypic variation. Then, colocalization analysis further identified genetic variants jointly influencing microbial abundance and metabolite traits, highlighting potential host-microbe-trait causal links. Incorporating microbiome data into genomic selection models, we successfully improved prediction accuracy for several traits, especially plant architecture and flowering. Together, this work provides a comprehensive population⍰level framework linking host genetics, microbiome composition, and agronomic traits in tobacco, offering new insights for microbiome⍰informed breeding strategies.

Holobiont works -> Phyllosphere and rhizosphere microbiomes empower Nicotiana tobacum complex traits dissection and prediction | bioRxiv

01.03.2026 17:54 — 👍 6 🔁 3 💬 1 📌 0

Progress in plant rhizosphere microbiome research for improved growth, nutrient uptake, and disease resistance • The rhizosphere microbiome regulates plant growth, nutrient uptake, and disease resistance through root - microbial crosstalk. • Microbial community assembly is driven by plant genotype, developmental stage, and soil properties. • The rhizosphere microbiome enhances plant growth via phytohormone production, nutrient solubilization, and nitrogen fixation. • Biofilm formation and ISR mechanisms boost disease resistance while reducing pesticide dependence. • Multi-omics and synthetic microbial consortia provide innovative tools for agricultural applications.

Progress in plant rhizosphere microbiome research for improved growth, nutrient uptake, and disease resistance - ScienceDirect

01.03.2026 17:51 — 👍 3 🔁 4 💬 0 📌 0

mGem: Applying microbiome therapeutic learnings to next-generation agricultural bioproducts Biological discoveries in plant and human systems have long advanced our understanding of how signaling, metabolism, and immunity shape cross-kingdom interactions. Building on this rich history of interdisciplinary insight, there is now a tremendous opportunity to strengthen connections between human and agricultural microbiome research. This perspective highlights key biological synergies across these systems that are essential for advancing human, agricultural, and ecosystem health. Focus is given to colonization, immune, and biosafety engineering strategies developed for microbiome therapeutics that can guide the design and development of next-generation agricultural bioproducts. Ultimately, greater knowledge exchange and collaboration across disciplines will be critical to translate microbiome discoveries into bioproducts with positive societal impact.

mGem: Applying microbiome therapeutic learnings to next-generation agricultural bioproducts

01.03.2026 17:49 — 👍 1 🔁 1 💬 0 📌 0

Host plant phylogeny predicts arbuscular mycorrhizal fungal communities, but plant life history and fungal genetic change predict feedback Symbioses exert strong influence on host phenotypes; however, benefits from symbionts can increase or degrade over time. Understanding the context-dependence of reinforcing or degrading dynamics is pivotal to predicting stability of symbiotic benefits. Host phylogenetic relationships and host life history traits are two candidate axes that have been proposed to structure symbioses. However, the relative influence of host evolutionary history and life history on symbiont composition, and whether changes in symbiont composition translate into stronger mutualistic benefits is unknown. We tested the influence of plant phylogenetic relationships and plant life history on the composition of arbuscular mycorrhizal (AM) fungi, perhaps the most ancestral and influential of plant symbionts, and then tested whether AM fungal differentiation resulted in improved mutualism as expected from coadaptation. We constructed mycobiomes composed of seven AM fungal isolates derived from tallgrass prairie and grew them for two growing seasons with 38 grassland plant species. We found that host phylogenetic structure was a significant predictor of the composition of AM fungal communities and the genetic composition of AM fungal species, patterns consistent with phylosymbiosis. However, the phylogenetic structure of AM fungi failed to translate to improved benefits to their host. While AM fungi generally improved plant growth and mycorrhizal feedback was generally positive, the strength of feedback was not predicted by plant phylogenetic distance. The composition of the AM fungal community and genetic composition within AM fungal species were also significantly influenced by plant life history and feedbacks between early and late successional species were generally positive. Interestingly, positive mycorrhizal feedback was predicted by changes in genetic composition of the two most abundant AM fungal species, not by changes in species composition. Positive mycorrhizal feedbacks across life history can mediate plant species turnover during succession and suggests that consideration of mycorrhizal dynamics could improve ecosystem restoration.

Host plant phylogeny predicts arbuscular mycorrhizal fungal communities, but plant life history and fungal genetic change predict feedback | PLOS Biology

01.03.2026 17:44 — 👍 5 🔁 2 💬 0 📌 0

Rhizoglomus clarum inoculation enhances drought tolerance and photosynthetic performance of maize in sterile and natural soils Drought is a major constraint on maize production worldwide, particularly in tropical regions where climate variability is intensifying. Arbuscular mycorrhizal fungi (AMF) have emerged as beneficial symbionts enhancing plant resilience to drought by improving water uptake, nutrient acquisition, and photosynthetic performance. This study evaluated the effects of Rhizoglomus clarum inoculation on maize growth, water status, osmotic adjustment, and chlorophyll a fluorescence under well-watered (WW) and water-deficit (WD) conditions in sterile and natural soils. The experiment was conducted in a greenhouse using a randomized complete block design in a 4 × 2 factorial scheme (soil treatment × water regime), with four replicates. Drought significantly reduced leaf area, shoot and root biomass, and water status. However, R. clarum inoculation attenuated these effects, increasing leaf dry mass by up to 45% and stem dry mass by 100% in under WD. Inoculated plants also showed higher photochemical efficiency (Fv/Fm and PIABS) under both water regimes. The strongest responses were observed in natural soil, suggesting synergistic interactions between R. clarum and indigenous microbiota. These results demonstrate that R. clarum enhances maize drought tolerance through coordinated morphological, physiological, and photochemical adjustments. This highlights the potential of species-specific AMF inoculation as a sustainable strategy to improve maize performance under water-limited conditions.

Rhizoglomus clarum inoculation enhances drought tolerance and photosynthetic performance of maize in sterile and natural soils | Research Square

01.03.2026 17:38 — 👍 0 🔁 1 💬 0 📌 0

CHASE-independent cytokinin perception triggers 3′,5′-cAMP signaling in Sinorhizobium meliloti The Medicago sativa-Sinorhizobium meliloti symbiotic plant-microbe interaction, which results in the formation of nitrogen-fixing root nodules, is subject to sophisticated genetic and metabolic regulation by both partners. S. meliloti is capable of inhibiting secondary plant infections via an adenosine 3′,5′-cyclic adenosine monophosphate (cAMP)-dependent regulatory pathway that depends on CHASE2 domain adenylate/guanylate cyclases (AC/GCs). This pathway likely responds to a plant signal of protein nature. Plant cytokinins (CKs) are adenine derivative phytohormones that control many aspects of plant development, including the symbiotic nodule formation. Classical CK receptors in plants and bacteria contain a CHASE domain. In our study, we present a novel, CK-dependent cAMP signaling pathway, specifically mediated by the AC/GC CyaB, which lacks any known receptor domains. The plant CKs N6(Δ2isopentenyl)-adenine (iP), trans-zeatin, kinetin, and 6-benzylaminopurine all promoted CyaB-dependent increase in cAMP levels detected through a genetic reporter construct. Among these four CKs, iP exerted the strongest effect. Metabolic profiling confirmed the CyaB-dependent accumulation of cAMP in S. meliloti cells, cultured in the presence of iP. The first enzyme in the terpenoid biosynthetic pathway, 1-deoxyxylulose-5-phosphate synthase Dxs, was identified as a CyaB interaction partner and is proposed to mediate the CK perception. CyaB homologs from closely related members of the Rhizobiaceae were able to interact with Dxs and to mediate cAMP signaling in response to iP.

Wow... Sinorhizobium meliloti can perceive plant cytokinins (CKs) through a novel, CHASE-independent mechanism involving the adenylate cyclase CyaB, which then triggers cAMP signaling -> CHASE-independent cytokinin perception triggers 3′,5′-cAMP signaling in Sinorhizobium meliloti

01.03.2026 17:37 — 👍 2 🔁 0 💬 0 📌 0

SydR, a redox-sensing MarR-type regulator of Sinorhizobium meliloti, is crucial for symbiotic infection of Medicago truncatula roots Rhizobia associate with legumes and induce the formation of nitrogen-fixing nodules. The regulation of bacterial redox state plays a major role in symbiosis, and reactive oxygen species produced by the plant are known to activate signaling pathways. However, only a few redox-sensing transcriptional regulators (TRs) have been characterized in the microsymbiont. Here, we describe SydR, a novel redox-sensing TR of Sinorhizobium meliloti that is essential for the establishment of symbiosis with Medicago truncatula. SydR, a MarR-type TR, represses the expression of the adjacent gene SMa2023 in growing cultures, and this repression is alleviated by NaOCl, tert-butyl hydroperoxide, or H2O2 treatment. Transcriptional psydR-gfp and pSMa2023-gfp fusions, as well as gel shift assays, showed that SydR binds two independent sites of the sydR-SMa2023 intergenic region. This binding is redox-dependent, and site-directed mutagenesis demonstrated that the conserved C16 is essential for SydR redox sensing. The inactivation of sydR did not alter the sensitivity of S. meliloti to NaOCl, tert-butyl hydroperoxide, or H2O2, nor did it affect the response to oxidants of the roGFP2-Orp1 redox biosensor expressed within bacteria. However, in planta, ΔsydR mutation impaired the formation of root nodules. Microscopic observations and analyses of plant marker gene expression showed that the ΔsydR mutant is defective at an early stage of the bacterial infection process. Altogether, these results demonstrated that SydR is a redox-sensing MarR-type TR that plays a key role in the regulation of nitrogen-fixing symbiosis with M. truncatula.

Fantastic paper from 2024... How did I miss it? ->
SydR, a redox-sensing MarR-type regulator of Sinorhizobium meliloti, is crucial for symbiotic infection of Medicago truncatula roots

27.02.2026 15:00 — 👍 1 🔁 0 💬 0 📌 0

Gibberellin biosynthesis in Lotus japonicus regulates arbuscule distribution, but not overall colonisation by arbuscular mycorrhizal fungi Gibberellins have been reported to play both positive and negative roles in arbuscular mycorrhizal (AM) symbioses. Despite extensive characterisation of the role of DELLAs in AM colonisation, studies of gibberellin function have largely been restricted to chemical interventions. Few studies have examined how disruption to gibberellin biosynthesis affects AM symbioses. To explore this further, we obtained Lotus japonicus LORE1 transposon insertion mutants in four key gibberellin biosynthetic genes: CPS, KS, KO, and KAO. Through a characterisation of their developmental phenotypes, we determined that for each gene there is a single homolog which has a major role in gibberellin biosynthesis. We name these genes CPS1, KS1, KO1, and KAO1. Mutations in these genes affect AM colonisation in the overall distribution of arbuscules, but not in total colonisation levels. These results are consistent with previous studies indicating that DELLAs control the number of cortical cell layers, and therefore regulate the number of cells able to accommodate arbuscules.

Frontiers | Gibberellin biosynthesis in Lotus japonicus regulates arbuscule distribution, but not overall colonisation by arbuscular mycorrhizal fungi

27.02.2026 03:05 — 👍 1 🔁 0 💬 0 📌 0

CRAGE-RB-PI-seq reveals transcriptional dynamics of plant-associated bacteria during root colonization Plant roots release a wide array of metabolites into the rhizosphere, shaping microbial communities and their functions. While metagenomics has expanded our understanding of these communities, little is known about the physiology of their members in host environments. Transcriptome analysis via RNA sequencing is a common approach to learning more, but its use has been challenging because of low bacterial biomass and interference from plant RNA. To overcome this, we developed a randomly-barcoded promoter-library insertion sequencing (RB-PI-seq) combined with chassis-independent recombinase-assisted genome engineering (CRAGE). Using Pseudomonas simiae WCS417 as a model rhizobacterium, this method enabled targeted amplification of barcoded transcripts, bypassing plant RNA interference and allowing measurement of thousands of promoter activities during Arabidopsis root colonization. Our analysis revealed temporally resolved transcriptional regulation, including those associated with cell growth, chemotaxis, plant immune suppression, biofilm formation, and stress responses, reflecting the coordinated physiological adaptation to the root environment. Additionally, we discovered that transcriptional activation of xanthine dehydrogenase and a lysozyme inhibitor is crucial for evading plant immune systems. This framework is scalable to other bacterial species and provides new opportunities for understanding rhizobacterial gene regulation in native environments.

CRAGE-RB-PI-seq reveals transcriptional dynamics of plant-associated bacteria during root colonization | Nature Communications

27.02.2026 02:59 — 👍 1 🔁 1 💬 0 📌 0

Extracellular ATP in plants: discovery, mechanisms, and integration The study of extracellular adenosine triphosphate (eATP) in plants has gained significant traction in recent years. Although plant responses to eATP were reported decades ago, the concept initially struggled to captivate widespread scientific interest, largely due to doubts about ATP’s role as a signal in plants. This perception shifted dramatically with the discovery of the plant purinoceptor P2K1, which has since become a cornerstone for research in this field, catalyzing the exploration of eATP-specific responses, the molecular components of its signaling pathways, and interactions with other key regulatory networks, such as plant hormone signaling. Today, the study of the plant purinergic system represents an advanced and dynamic research area, offering insights into how plants perceive and respond to environmental stimuli and internal cues. This chapter provides a comprehensive overview of the evolution of eATP research, beginning with its historical context and tracing the development of our understanding of plant purinergic signaling. Particular emphasis is placed on the mechanisms underlying eATP release, turnover, perception, and response, highlighting recent discoveries and their implications for plant physiology and cross-communication with other signaling pathways.

Extracellular ATP in plants: discovery, mechanisms, and integration - ScienceDirect

27.02.2026 02:55 — 👍 1 🔁 0 💬 0 📌 0

Promoting nitrogen fixation by threonine synthesis in co-culture of Azotobacter vinelandii and Escherichia coli Amino acid production directly from N2 is a big challenge in green biomanufacturing. Merging biological nitrogen fixation (BNF) with target amino acid biosynthesis in co-culture system offers a promising solution. Here, we constructed a Nitrogen Fixation-Utilization Coupling (NFUC) system that enabled threonine production directly from N2 and ethanol, by co-culturing engineered Azotobacter vinelandii for BNF and Escherichia coli for threonine biosynthesis. Systematic metabolic engineering increased threonine titer 3.4-fold over the initial co-culture through optimizing NH4+ release, threonine pathway and energy supply. The nitrogen fixation activity of Azotobacter vinelandii was enhanced in co-culture by the demand for threonine synthesis, resulting in an improvement in total fixed nitrogen compared to its monoculture. The observed downregulation of glutamine synthetase activity in co-cultured Azotobacter vinelandii revealed its prioritization of N2 fixation over endogenous amino acid synthesis, enhancing NH4+ availability for Escherichia coli with an increase in extracellular NH4+ level. This NFUC system establishes a platform for sustainable bioproduction of amino acids directly from N2.

Promoting nitrogen fixation by threonine synthesis in co-culture of Azotobacter vinelandii and Escherichia coli - ScienceDirect

27.02.2026 02:49 — 👍 2 🔁 0 💬 0 📌 0

Evolution and variation of gene modules associated with symbiotic nitrogen fixation in the nitrogen-fixing clade Trait-based hidden Markov model reconstructions of NFC ancestral states are inferred from a binary nodulation phenotype. As a result, they do not incorporate how the symbiosis-associated gene modules and cis-regulatory landscapes evolve across the clade. Here, we consider the non-precursor, precursor, and intermediate hidden states proposed by Kates et al. (2024) as model-based ancestral categories. These categories provide a schematic (not lineage-specific) framework linking trait reconstructions to plausible changes in gene content and cis-regulatory innovation (Figure 1A). In this view, the hypothesized predisposition in the MRCA of the NFC may have involved coordinated remodeling of the CSSP, key transcriptional regulators (e.g., NIN), and cis-regulatory architecture.

Evolution and variation of gene modules associated with symbiotic nitrogen fixation in the nitrogen-fixing clade

27.02.2026 02:46 — 👍 0 🔁 0 💬 0 📌 0

Reposting this because I'll never pass up an opportunity to introduce people to the wonderful world of sheoaks.

To be clear, this is family of ANGIOSPERMS with feaux needles/cones most closely related to BIRCHES.

Oh, and they also fix nitrogen to boot! Then again, so do the closely-related alders.

26.02.2026 16:47 — 👍 4 🔁 2 💬 0 📌 0

What lurks beneath the surface? The hidden Frankia biodiversity in Casuarina nodules across continents | Research Square Background and Aims Actinorhizal root nodule symbioses are formed between a diverse group of mostly woody dicotyledonous plants and nitrogen-fixing soil Actinomycetota of the genus Frankia. One of the most ecologically relevant actinorhizal plants are (Allo-)Casuarina species, used widely in shelter belts and phytoremediation due to their high tolerance to abiotic stresses and ability to thrive on marginal soils. All sequenced Frankia strains isolated from (Allo-)Casuarina nodules via traditional techniques show high sequence identity and belong to a single species, Frankia casuarinae. This lack of diversity in nodules is unusual in actinorhizal symbioses. We hypothesised that (Allo-)Casuarina nodules are colonized by Frankia strains that cannot be cultivated and exhibit genome erosion. Methods To test this, we directly sequenced nodule metagenomes from four countries, followed by reconstruction of metagenome-assembled genomes (MAGs). Results Our findings show that the dominant Frankia strains in field samples were far more diverse than the isolated strains and included MAGs with substantial genome reduction – one exhibiting over 25% reduction compared to F. casuarinae. Notably, we observed erosion of two types of [NiFe] hydrogenases, a phenomenon linked to evolution toward obligate symbiosis in other Frankia groups. Conclusion These results suggest that potentially obligate symbionts may dominate nodules in nature but had gone undetected by conventional approaches. For applications such as reforestation or tsunami shelter belts, crushed, nodule-derived strains may offer superior ecological compatibility. We speculate that Frankia strains followed two different evolutionary trajectories; one, towards obligate symbiosis accompanied by strong genome erosion, and two, towards rhizosphere colonization involving limited genome erosion.

Very cool preprint! -> What lurks beneath the surface? The hidden Frankia biodiversity in Casuarina nodules across continents | Research Square

26.02.2026 16:22 — 👍 4 🔁 1 💬 0 📌 1

Interactions between native soil microbiome and a synthetic microbial community reveals bacteria with persistent traits Synthetic microbial communities (SynComs) are curated microbial groups that can be designed to optimize microbial functions, such as enhancing plant growth or disease resistance. Attaining SynCom stability in the presence of native soil communities remains a key challenge. This study investigated the survival, persistence, and chemical interactions of a SynCom with a native soil microbial community using a transwell system that spatially constrains bacteria while permitting chemical interactions. The SynCom, composed of six compatible Pseudomonas species identified through whole-genome sequencing, was analyzed for antagonistic interactions with native microbes over time and assessed using biomass and viability measurements. Over time, the SynCom exhibited reduced growth in the presence of native soil microbes compared to the SynCom not exposed to the native microbes. Flow cytometry analysis showed an 81% reduction of live cells for the persistent strain in the presence of native microbes and a 78% and 99% increase in dead and unstained cells, respectively. Compared to a non-persistent strain, one persistent SynCom strain showed lower metabolic utilization across five key compound classes: polymers, carboxylic acids, amino acids, amines, and phenols when exposed to the native soil microbes. These findings underscore the importance of understanding complex SynCom-environment interactions to enhance SynCom stability and optimize in situ applications.

It bothers me to call these 6 Pseudomonas strains a SynCom simply because they don't kill each other... What do you think?

Interactions between native soil microbiome and a synthetic microbial community reveals bacteria with persistent traits

26.02.2026 15:58 — 👍 4 🔁 0 💬 0 📌 0

Long-term nitrogen fertilizer improves nitrogen use efficiency and wheat yield by regulating the interactions of rhizosphere soil-root-microbes Nitrogen (N) fertilizer is widely used in agroecosystems to maintain and improve soil fertility while affecting soil microbial communities. The ability of root to absorb nutrients is critically mediated by these soil microbial communities, ultimately determining crop growth and yield formation. Thus, comprehensively understanding the rhizosphere root-soil-microbe interaction mechanism is critical for synergistically regulating nitrogen use efficiency (NUE) and yield. Here, a 13-year field experiment in a wheat-maize rotation system was conducted to explore the effects of N fertilizer on soil physicochemical properties, root parameters and rhizosphere microorganisms. Compared with N0 (0 kg ha−1), moderate N application (180–240 kg ha−1) optimized soil nutrient availability, as evidenced by increasing available nitrogen (AN) and ammonium-N (NH4+-N) by 17.42 %–27.33 % and 12.24 %–6 2.49 %, respectively, and enhanced root morphology, with root vessel diameter (RVD), root length density (RLD), and root weight density (RWD) rising by 5.12 %–21.57 %, 14.17 %–65.77 %, and 3.46 %–62.10 %, respectively. Consequently, N uptake and metabolic enzyme activities were significantly boosted. These root modifications, in turn, reshaped the rhizosphere microbiome by enriching beneficial bacterial and fungal taxa, Pseudomonadota and Basidiomycota increased by an average of 20.93 % and 73.28 %, facilitating efficient N cycling and organic matter decomposition. Structural equation model (SEM) revealed that soil N and root enzyme activity mediated microbial community compositions and diversity, which collectively enhanced both yield and NUE. Overall, our findings highlight the critical role of root-microbe feedback in driving N efficiency and propose that optimizing N inputs can sustainably enhance crop productivity by leveraging soil-plant-microbial synergies.

I see only correlation data in this manuscript, but a big title claiming causation -> Long-term nitrogen fertilizer improves nitrogen use efficiency and wheat yield by regulating the interactions of rhizosphere soil-root-microbes - ScienceDirect

24.02.2026 19:37 — 👍 1 🔁 1 💬 0 📌 0

Soilless system design impacts the diversity and composition of microbiota | bioRxiv Controlled environment agriculture (CEA), including soilless farming systems, is rapidly expanding as a strategy to improve food security and resource efficiency. However, limited information is available on how different soilless farming system designs influence microbial populations relevant to plant health and food safety. This study investigated the effects of soilless growing systems and growing season on aerobic plate counts (APC) and bacterial community composition in nutrient solution and on bok choy (Brassica rapa subsp. chinensis) leaves. Five soilless systems, deep water culture (DWC), Kratky (KR), nutrient film technique (NFT), ebb and flow (EF), and drip irrigation (DI), were evaluated across fall and spring growing seasons. Soilless system type significantly influenced APC in nutrient solution, with the DI system consistently exhibiting the highest counts across both seasons. Increased nutrient solution pH was negatively associated with APC, whereas temperature did not significantly affect bacterial concentrations. In contrast, APC on bok choy leaves were not significantly influenced by system type, season, pH, or temperature. Bacterial community composition in nutrient solution was strongly shaped by season, soilless system type, sampling day, and temperature, as determined by 16S rRNA V4 amplicon sequencing. Microbial diversity varied primarily by system type, with limited influence of pH or temperature. Core microbiota analysis identified a small subset of taxa that persisted across systems and seasons, with Acidovorax detected in all samples. We found that soilless system design and seasonal conditions strongly influence microbial load and community structure in nutrient solution, providing a foundation for developing system-specific microbial management strategies.

Interesting but a bit obvious... Soilless system design impacts the diversity and composition of microbiota | bioRxiv

24.02.2026 19:33 — 👍 0 🔁 0 💬 0 📌 0

Interesting study, but... it uses terms from the 1970s to describe root nodule nitrogen fixation in legumes. Symbiotic nitrogen fixation also occurs in non-legume crops. I'm a bit annoyed that the reviewers did not catch that.

24.02.2026 19:29 — 👍 0 🔁 0 💬 0 📌 0

Poplar CLE peptides promoting ectomycorrhizal symbiosis identified through genome-wide analysis of responsive small secreted peptides Trees use CLAVATA3/EMBRYO SURROUNDING REGION-related (CLE) peptides to promote ectomycorrhizal symbiosis, revealing an additional regulatory layer in tree–

🧵 New paper out in @PlantPhysiology! We asked: how do trees talk to their fungal partners during ectomycorrhizal symbiosis? Turns out, tiny secreted peptides play a big role. 1/

Read the full paper here 👇
academic.oup.com/plphys/advan...

24.02.2026 14:03 — 👍 46 🔁 20 💬 1 📌 1

Calcium signaling in plants: Universal and unique paradigms Rooted in place, plants must continuously respond and adapt to their ever-changing environment to survive, especially as climate change intensifies. Calcium ions (Ca²⁺) play a central role in plant responses to both biotic and abiotic challenges. Ca²⁺ signaling involves the coordinated action of channels and transporters that generate specific “Ca²⁺ codes,” along with Ca²⁺-binding proteins that act as sensors to decode them. Studies over the past several decades have explored the molecular components that form the toolkit, pathways, and networks for the coding and decoding of Ca²⁺ signals in plants. This review focuses on the emerging mechanisms of calcium signaling in plants, beginning with an overview of the universal conceptual framework that governs the coding and decoding of Ca²⁺ signals, followed by examples of pathways in plant growth and reproduction, responses to abiotic stress and microbes, and systemic signaling in plants.

Outstanding review -> Calcium signaling in plants: Universal and unique paradigms

24.02.2026 00:17 — 👍 2 🔁 0 💬 0 📌 0

Opinion | What Happened in Chicago When Science Became the Enemy

This is a good article, gift link.
It illustrates the real impacts that are occurring from the current US government's attacks on science funding 👍
www.nytimes.com/2026/02/23/o...

23.02.2026 18:14 — 👍 12 🔁 10 💬 0 📌 2

Regulation of metabolite production during the encounter between the actinobacterium Frankia and its host Alnus glutinosa | Research Square Our study focuses on the metabolomic changes observed during the early stages of Alnus glutinosa and Frankia alni symbiosis. Amino acid metabolic profiling by HPLC-DAD-FLD and untargeted metabolomic analysis of secondary metabolites by UHPLC-QTOF were performed on the shoots and roots of A. glutinosa as well as on bacterial pellets of F. alni. Two culture conditions were compared: a single culture condition (where A. glutinosa or Frankia was grown alone) and a co-culture condition (where A. glutinosa and Frankia were grown together) at different culture times (D1, D2 and D3). Our results reveal a change in metabolism (primary and secondary) in both partners in the co-culture condition. For amino acids, this change was more important in the shoots than in the roots and in Frankia. A total of 16 amino acids (Asp, Asn, Ser, Gln, Gly, Cit, GABA, Ala, Arg, Tyr, Trp Val, Phe, Ile, Lys and Pro) were overproduced in the presence of Frankia in the shoots on the different sampling days. We hypothesised that the plant would modify its amino acid content in its shoots in anticipation of a transfer to Frankia for growth. At the same time, a drastic change in secondary metabolites occurs in the shoots, roots and Frankia at the three time points considered between the control condition and the co-culture condition. Statistical analyses enabled us to highlight the ions characterising the co-culture condition in the different biological compartments (i.e. shoots, roots and Frankia). The biomarkers identified in the shoots and Frankia varied greatly depending on the sampling day (i.e. D1, D2 and D3), revealing strong dynamics. The root biomarkers appear to be more stable over time, as several of them are common to all three sampling days.

Regulation of metabolite production during the encounter between the actinobacterium Frankia and its host Alnus glutinosa | Research Square

21.02.2026 23:01 — 👍 1 🔁 0 💬 0 📌 0

Posts by Jean-Michel Ané (@jeanmichelane.bsky.social)