Cancer cell-intrinsic biosynthesis of itaconate promotes tumor immunogenicity.

The Krebs cycle byproduct itaconate has recently emerged as an important metabolite regulating macrophage immune functions, but its role in tumor cells remains unknown. Here, we show that increased tumor-intrinsic cis-aconitate decarboxylase (ACOD1 or CAD, encoded by immune-responsive gene 1, Irg1) expression and itaconate production promote tumor immunogenicity and anti-tumor immune responses. Furthermore, we identify thimerosal, a vaccine preservative, as a specific inducer of IRG1 expression in tumor cells but not in macrophages, thereby enhancing tumor immunogenicity. Mechanistically, thimerosal induces itaconate production through a ROS-RIPK3-IRF1 signaling axis in tumor cells. Further, increased IRG1/itaconate upregulates antigen presentation-related gene expression via promoting TFEB nuclear translocation. Intratumoral injection of thimerosal induced itaconate production, activated the tumor immune microenvironment, and inhibited tumor growth in a T cell-dependent manner. Importantly, IRG1 deficiency markedly impaired tumor response to thimerosal treatment. Furthermore, itaconate induction by thimerosal potentiates the anti-tumor efficacy of adoptive T-cell therapy and anti-PD1 therapy in a mouse lymphoma model. Hence, our findings identify a new role for tumor intrinsic IRG1/itaconate in promoting tumor immunogenicity and provide a translational means to increase immunotherapy efficacy.

Noncoding RNA circBtnl1 suppresses self-renewal of intestinal stem cells via disruption of Atf4 mRNA stability.

Intestinal stem cells (ISCs) at the crypt base are responsible for the regeneration of the intestinal epithelium. However, how ISC self-renewal is regulated still remains unclear. Here we identified a circular RNA, circBtnl1, that is highly expressed in ISCs. Loss of circBtnl1 in mice enhanced ISC self-renewal capacity and epithelial regeneration, without changes in mRNA and protein levels of its parental gene Btnl1. Mechanistically, circBtnl1 and Atf4 mRNA competitively bound the ATP-dependent RNA helicase Ddx3y to impair the stability of Atf4 mRNA in wild-type ISCs. Furthermore, ATF4 activated Sox9 transcription by binding to its promoter via a unique motif, to enhance the self-renewal capacity and epithelial regeneration of ISCs. In contrast, circBtnl1 knockout promoted Atf4 mRNA stability and enhanced ATF4 expression, which caused Sox9 transcription to potentiate ISC stemness. These data indicate that circBtnl1-mediated Atf4 mRNA decay suppresses Sox9 transcription that negatively modulates self-renewal maintenance of ISCs.

Structure of mycobacterial ATP synthase bound to the tuberculosis drug bedaquiline.

Tuberculosis-the world's leading cause of death by infectious disease-is increasingly resistant to current first-line antibiotics1. The bacterium Mycobacterium tuberculosis (which causes tuberculosis) can survive low-energy conditions, allowing infections to remain dormant and decreasing their susceptibility to many antibiotics2. Bedaquiline was developed in 2005 from a lead compound identified in a phenotypic screen against Mycobacterium smegmatis3. This drug can sterilize even latent M. tuberculosis infections4 and has become a cornerstone of treatment for multidrug-resistant and extensively drug-resistant tuberculosis1,5,6. Bedaquiline targets the mycobacterial ATP synthase3, which is an essential enzyme in the obligate aerobic Mycobacterium genus3,7, but how it binds the intact enzyme is unknown. Here we determined cryo-electron microscopy structures of M. smegmatis ATP synthase alone and in complex with bedaquiline. The drug-free structure suggests that hook-like extensions from the α-subunits prevent the enzyme from running in reverse, inhibiting ATP hydrolysis and preserving energy in hypoxic conditions. Bedaquiline binding induces large conformational changes in the ATP synthase, creating tight binding pockets at the interface of subunits a and c that explain the potency of this drug as an antibiotic for tuberculosis.

KCTD10 regulates brain development by destabilizing brain disorder-associated protein KCTD13.

KCTD10 belongs to the KCTD (potassiumchannel tetramerization domain) family, many members of which are associated with neuropsychiatric disorders. However, the biological function underlying the association with brain disorders remains to be explored. Here, we reveal that Kctd10 is highly expressed in neuronal progenitors and layer V neurons throughout brain development. Kctd10 deficiency triggers abnormal proliferation and differentiation of neuronal progenitors, reduced deep-layer (especially layer V) neurons, increased upper-layer neurons, and lowered brain size. Mechanistically, we screened and identified a unique KCTD10-interacting protein, KCTD13, associated with neurodevelopmental disorders. KCTD10 mediated the ubiquitination-dependent degradation of KCTD13 and KCTD10 ablation resulted in a considerable increase of KCTD13 expression in the developing cortex. KCTD13 overexpression in neuronal progenitors led to reduced proliferation and abnormal cell distribution, mirroring KCTD10 deficiency. Notably, mice with brain-specific Kctd10 knockout exhibited obvious motor deficits. This study uncovers the physiological function of KCTD10 and provides unique insights into the pathogenesis of neurodevelopmental disorders.

Author Correction: The Apostasia genome and the evolution of orchids.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

An endoscopically compatible fast-gelation powder forms Janus-adhesive hydrogel barrier to prevent postoperative adhesions.

Postoperative adhesions occur widely in various tissues, bringing the risk of secondary surgery and increased medical burden. Hydrogel barriers with Janus-adhesive ability can achieve physical isolation of adjacent tissues and are therefore considered an ideal solution. However, integrating endoscopic delivery convenience and viscoelastic Janus hydrogel formation remains a great challenge. Here, we present a report of the in situ formation of Janus-adhesive hydrogel barrier using a sprayable fast-Janus-gelation (FJG) powder. We first methacrylate the polysaccharide macromolecules to break the intermolecular hydrogen bonds and impart the ability of rapid hydration. FJG powder can rapidly absorb interfacial water and crosslink through borate ester bonds, forming a toughly adhesive viscoelastic hydrogel. The Janus barrier can be simply formed by further hydrating the upper powder with cationic solution. We construct rat models to demonstrate the antiadhesions efficiency of viscoelastic FJG hydrogels in organs with different motion modalities (e.g., intestine, heart, liver). We also developed a low-cost delivery device with a standardized surgical procedure and further validated the feasibility and effectiveness of FJG powder in minimally invasive surgery using a preclinical translational porcine model. Considering the advantages in terms of therapeutic efficacy, clinical convenience, and commercialization, our results reveal the great potential of Janus-gelation powder materials as a next-generation antiadhesions barrier.

Extracellular matrix physical properties govern the diffusion of nanoparticles in tumor microenvironment.

Nanoparticles (NPs) are confronted with limited and disappointing delivery efficiency in tumors clinically. The tumor extracellular matrix (ECM), whose physical traits have recently been recognized as new hallmarks of cancer, forms a main steric obstacle for NP diffusion, yet the role of tumor ECM physical traits in NP diffusion remains largely unexplored. Here, we characterized the physical properties of clinical gastric tumor samples and observed limited distribution of NPs in decellularized tumor tissues. We also performed molecular dynamics simulations and in vitro hydrogel experiments through single-particle tracking to investigate the diffusion mechanism of NPs and understand the influence of tumor ECM physical properties on NP diffusion both individually and collectively. Furthermore, we developed an estimation matrix model with evaluation scores of NP diffusion efficiency through comprehensive analyses of the data. Thus, beyond finding that loose and soft ECM with aligned structure contribute to efficient diffusion, we now have a systemic model to predict NP diffusion efficiency based on ECM physical traits and provide critical guidance for personalized tumor diagnosis and treatment.

ADGRL1 haploinsufficiency causes a variable spectrum of neurodevelopmental disorders in humans and alters synaptic activity and behavior in a mouse model.

ADGRL1 (latrophilin 1), a well-characterized adhesion G protein-coupled receptor, has been implicated in synaptic development, maturation, and activity. However, the role of ADGRL1 in human disease has been elusive. Here, we describe ten individuals with variable neurodevelopmental features including developmental delay, intellectual disability, attention deficit hyperactivity and autism spectrum disorders, and epilepsy, all heterozygous for variants in ADGRL1. In vitro, human ADGRL1 variants expressed in neuroblastoma cells showed faulty ligand-induced regulation of intracellular Ca2+ influx, consistent with haploinsufficiency. In vivo, Adgrl1 was knocked out in mice and studied on two genetic backgrounds. On a non-permissive background, mice carrying a heterozygous Adgrl1 null allele exhibited neurological and developmental abnormalities, while homozygous mice were non-viable. On a permissive background, knockout animals were also born at sub-Mendelian ratios, but many Adgrl1 null mice survived gestation and reached adulthood. Adgrl1-/- mice demonstrated stereotypic behaviors, sexual dysfunction, bimodal extremes of locomotion, augmented startle reflex, and attenuated pre-pulse inhibition, which responded to risperidone. Ex vivo synaptic preparations displayed increased spontaneous exocytosis of dopamine, acetylcholine, and glutamate, but Adgrl1-/- neurons formed synapses in vitro poorly. Overall, our findings demonstrate that ADGRL1 haploinsufficiency leads to consistent developmental, neurological, and behavioral abnormalities in mice and humans.

NAMPT promotes the malignant progression of HBV-associated hepatocellular carcinoma through activation of SREBP1-mediated lipogenesis.

Metabolic reprogramming is a hallmark of cancer. The nicotinamide phosphoribosyltransferase (NAMPT)-mediated salvage pathway maintains sufficient cellular NAD levels and is required for tumorigenesis and development. However, the molecular mechanism by which NAMPT contributes to HBV-associated hepatocellular carcinoma (HCC) remains not fully understood. In the present study, our results showed that NAMPT protein was obviously upregulated in HBV-positive HCC tissues compared with HBV-negative HCC tissues. NAMPT was positively associated with aggressive HCC phenotypes and poor prognosis in HBV-positive HCC patients. NAMPT overexpression strengthened the proliferative, migratory, and invasive capacities of HBV-associated HCC cells, while NAMPT-insufficient HCC cells exhibited decreased growth and mobility. Mechanistically, we demonstrated that NAMPT activated SREBP1 (sterol regulatory element-binding protein 1) by increasing the expression and nuclear translocation of SREBP1, leading to the transcription of SREBP1 downstream lipogenesis-related genes and the production of intracellular lipids and cholesterol. Altogether, our data uncovered an important molecular mechanism by which NAMPT promoted HBV-induced HCC progression through the activation of SREBP1-triggered lipid metabolism reprogramming and suggested NAMPT as a promising prognostic biomarker and therapeutic target for HBV-associated HCC patients.

Autism patient-derived SHANK2BY29X mutation affects the development of ALDH1A1 negative dopamine neuron.

Autism spectrum disorder (ASD) encompasses a range of neurodevelopmental conditions. Different mutations on a single ASD gene contribute to heterogeneity of disease phenotypes, possibly due to functional diversity of generated isoforms. SHANK2, a causative gene in ASD, demonstrates this phenomenon, but there is a scarcity of tools for studying endogenous SHANK2 proteins in an isoform-specific manner. Here, we report a point mutation on SHANK2, which is found in a patient with autism, located on exon of the SHANK2B transcript variant (NM_133266.5), hereby SHANK2BY29X. This mutation results in an early stop codon and an aberrant splicing event that impacts SHANK2 transcript variants distinctly. Induced pluripotent stem cells (iPSCs) carrying this mutation, from the patient or isogenic editing, fail to differentiate into functional dopamine (DA) neurons, which can be rescued by genetic correction. Available SMART-Seq single-cell data from human midbrain reveals the abundance of SHANK2B transcript in the ALDH1A1 negative DA neurons. We then show that SHANK2BY29X mutation primarily affects SHANK2B expression and ALDH1A1 negative DA neurons in vitro during early neuronal developmental stage. Mice knocked in with the identical mutation exhibit autistic-like behavior, decreased occupancy of ALDH1A1 negative DA neurons and decreased dopamine release in ventral tegmental area (VTA). Our study provides novel insights on a SHANK2 mutation derived from autism patient and highlights SHANK2B significance in ALDH1A1 negative DA neuron.

Monoallelic loss-of-function variants in GSK3B lead to autism and developmental delay.

De novo variants adjacent to the canonical splicing sites or in the well-defined splicing-related regions are more likely to impair splicing but remain under-investigated in autism spectrum disorder (ASD). By analyzing large, recent ASD genome sequencing cohorts, we find a significant burden of de novo potential splicing-disrupting variants (PSDVs) in 5048 probands compared to 4090 unaffected siblings. We identified 55 genes with recurrent de novo PSDVs that were highly intolerant to variation. Forty-six of these genes have not been strongly implicated in ASD or other neurodevelopmental disorders previously, including GSK3B. Through international, multicenter collaborations, we assembled genotype and phenotype data for 15 individuals with GSK3B variants and identified common phenotypes including developmental delay, ASD, sleeping disturbance, and aggressive behavior. Using available single-cell transcriptomic data, we show that GSK3B is enriched in dorsal progenitors and intermediate forms of excitatory neurons in the developing brain. We showed that Gsk3b knockdown in mouse excitatory neurons interferes with dendrite arborization and spine maturation which could not be rescued by de novo missense variants identified from affected individuals. In summary, our findings suggest that PSDVs may play an important role in the genetic etiology of ASD and allow for the prioritization of new ASD candidate genes. Importantly, we show that genetic variation resulting in GSK3B loss-of-function can lead to a neurodevelopmental disorder with core features of ASD and developmental delay.

A fungal effector suppresses the nuclear export of AGO1-miRNA complex to promote infection in plants.

Communication between interacting organisms via bioactive molecules is widespread in nature and plays key roles in diverse biological processes. Small RNAs (sRNAs) can travel between host plants and filamentous pathogens to trigger transkingdom RNA interference (RNAi) in recipient cells and modulate plant defense and pathogen virulence. However, how fungal pathogens counteract transkingdom antifungal RNAi has rarely been reported. Here we show that a secretory protein VdSSR1 (secretory silencing repressor 1) from Verticillium dahliae, a soil-borne phytopathogenic fungus that causes wilt diseases in a wide range of plant hosts, is required for fungal virulence in plants. VdSSR1 can translocate to plant nucleus and serve as a general suppressor of sRNA nucleocytoplasmic shuttling. We further reveal that VdSSR1 sequesters ALY family proteins, adaptors of the TREX complex, to interfere with nuclear export of the AGO1­microRNA (AGO1­miRNA) complex, leading to a great attenuation in cytoplasmic AGO1 protein and sRNA levels. With this mechanism, V. dahliae can suppress the accumulation of mobile plant miRNAs in fungal cells and succedent transkingdom silencing of virulence genes, thereby increasing its virulence in plants. Our findings reveal a mechanism by which phytopathogenic fungi antagonize antifungal RNAi-dependent plant immunity and expand the understanding on the complex interaction between host and filamentous pathogens.

Visualization of Unconventional Rashba Bands and Vortex Zero Mode in the Topological Superconductor Candidate AuSn4.

The noble metal alloy AuSn4 has recently been identified as an intrinsic surface topological superconductor, promisingly hosting the Majorana zero mode (MZM) for topological quantum computing. However, the atomic visualization of its nontrivial surface states and MZM remains elusive. Here, we report the direct observation of unconventional surface states and vortex zero mode in AuSn4 by scanning tunneling microscopy/spectroscopy. Unlike the trivial metallic bulk states of Sn-terminated surfaces, the Au-terminated surfaces exhibit pronounced surface states near the Fermi level, arising from unconventional Rashba bands characterized by shared helical spin textures. In the superconducting state, the Sn-terminated surfaces exhibit conventional Caroli-de Gennes-Matricon bound states, while the Au-terminated surfaces display sharp zero-energy core states resembling MZMs in a nonquantum-limit condition. This distinction may result from the dominant contribution of unconventional Rashba bands on the Au-terminated surface. Our results provide a new platform for studying termination-dependent topological surface states and MZM in noble-metal-based superconductors.

Diabetes mellitus and Alzheimer's disease: Vacuolar adenosine triphosphatase as a potential link.

Globally, the incidence of diabetes mellitus (DM) and Alzheimer's disease (AD) is increasing year by year, causing a huge economic and social burden, and their pathogenesis and aetiology have been proven to have a certain correlation. In recent years, more and more studies have shown that vacuolar adenosine triphosphatases (v-ATPases) in eukaryotes, which are biomolecules regulating lysosomal acidification and glycolipid metabolism, play a key role in DM and AD. This article describes the role of v-ATPase in DM and AD, including its role in glycolysis, insulin secretion and insulin resistance (IR), as well as its relationship with lysosomal acidification, autophagy and ß-amyloid (Aß). In DM, v-ATPase is involved in the regulation of glucose metabolism and IR. v-ATPase is closely related to glycolysis. On the one hand, v-ATPase affects the rate of glycolysis by affecting the secretion of insulin and changing the activities of key glycolytic enzymes hexokinase (HK) and phosphofructokinase 1 (PFK-1). On the other hand, glucose is the main regulator of this enzyme, and the assembly and activity of v-ATPase depend on glucose, and glucose depletion will lead to its decomposition and inactivation. In addition, v-ATPase can also regulate free fatty acids, thereby improving IR. In AD, v-ATPase can not only improve the abnormal brain energy metabolism by affecting lysosomal acidification and autophagy but also change the deposition of Aß by affecting the production and degradation of Aß. Therefore, v-ATPase may be the bridge between DM and AD.

Small nucleolar RNA Snora73 promotes psoriasis progression by sponging miR-3074-5p and regulating PBX1 expression.

Chronic psoriasis is a kind of immune-mediated skin illness and the underlying molecular mechanisms of pathogenesis remain incompletely understood. Here, we used small RNA microarray assays to scan the differential expressed RNAs in psoriasis patient samples. The downstream miRNAs and its targets were predicted using bioinformatics analysis from online bases and confirmed using fluorescence in situ hybridization and dual­luciferase report gene assay. Cell ability of proliferation and migration were detected using CCK-8 and transwell assays. The results showed that a new snoRNA Snora73 was upregulated in psoriasis patient samples. Overexpression of Snora73 significantly increased psoriasis cells viability and migration, while knockdown of Snora73 got the opposite results. Mechanistically, our results showed that Snora73 acted as a sponge for miR-3074-5p and PBX1 is a direct target of miR-3074-5p in psoriasis cells. Furthermore, miR-3074-5p suppressed psoriasis cell proliferation and migration, while PBX1 promoted cell proliferation and migration in psoriasis. Collectively, these findings reveal a crucial role of Snora73 in progression of psoriasis through miR-3074-5p/PBX1 signaling pathway and suggest a potential therapeutic strategy.

Investigating the Role of Extracellular Matrix Stiffness in Modulating the Ferroptosis Process in Hepatocellular Carcinoma Cells via Scanning Electrochemical Microscopy.

Extracellular matrix (ECM) stiffness modulates a variety of cellular processes, including ferroptosis, a process with significant potential implications for hepatocellular carcinoma (HCC) fibrosis and cirrhosis. However, the exact relationship between ECM stiffness and HCC ferroptosis is yet unclarified, partially due to the lack of in situ information on key parameters of the ferroptosis process of living HCC cells. This study pioneers the use of in vitro mechanical microenvironment models of HCC and the scanning electrochemical microscopy (SECM) technique for understanding this interplay. We first cultured HuH7 cells on 4.0, 18.0, and 44.0 kPa polyacrylamide (PA) gels to simulate early, intermediate, and advanced HCC ECM stiffness, respectively. Then, we used SECM to in situ monitor changes in cell membrane permeability, respiratory activity, and reactive oxygen species (ROS) levels of erastin-induced HuH7 cells on PA gels, finding that increasing ECM stiffness potentiates ferroptosis, including increased membrane permeabilization and H2O2 release as well as reduced respiratory activity. Through further transcriptome sequencing and molecular biology measurements, we identified a critical role for focal adhesion kinase (FAK)-mediated yes-associated protein (YAP) in regulating the ferroptosis process dependent on ECM stiffness, which provides novel insights into the mechanical regulation of ferroptosis in HCC cells and may pave the way for innovative therapeutic strategies.

Combination of IL-33 with PD-1 blockade augment mILC2s-mediated anti-tumor immunity.

BACKGROUND: Group 2 innate lymphoid cells (ILC2s) represent one of the main tissue-specific innate lymphoid cell populations, which are key drivers of cytokine secretion in their occupational niche. However, the precise involvement of ILC2s in cancer immunity and their potential impact on immunotherapeutic approaches remain poorly understood. METHODS: The proportion of ILC2s originating from various tissue sources were quantified through flow cytometry, along with the determination of CD4+ T cell and CD8+ T cell percentages. Flow cytometry was also employed to assess IFN-γ production and programmed cell death protein-1 (PD-1) expression in T cells. Immunohistochemistry was utilized to detect IL-33 expression in tumor tissues, while immunofluorescence was employed to confirm the infiltration of ILC2s in both murine and human tumor tissues. RESULTS: In this study, we provide evidence that intra-tumoral ILC2s in lung adenocarcinoma (LUAD) exist in a quiescent state. However, the activation of intra-tumoral ILC2s is induced by IL-33 specifically in a natural ILC2s (nILC2, ST2+KLRG1-) phenotype. Considering the pivotal role of PD-1 in cancer immunotherapy and its immunoregulatory functions, we investigated the synergistic effects of IL-33 and anti-PD-1 and found that their combination enhances anti-tumor immunity and improves the efficacy of immunotherapy. Moreover, this combination leads to the upregulation of activated mature ILC2s (mILC2, ST2+KLRG1+) phenotype, thereby highlighting the activated ILC2s as a novel enhancer of the immunoregulatory properties of anti-PD-1. CONCLUSIONS: Collectively, these findings underscore the significance of ILC2s and their contribution to the anti-tumor response in the context of cancer immunotherapy. Consequently, the simultaneous targeting of ILC2s and T cells represents a potentially promising and widely applicable strategy for immunotherapeutic interventions.

Genome-wide analysis of the KNOX gene family in Moso bamboo: insights into their role in promoting the rapid shoot growth.

BACKGROUND: KNOTTED1-like homeobox (KNOX) genes, plant-specific homologous box transcription factors (TFs), play a central role in regulating plant growth, development, organ formation, and response to biotic and abiotic stresses. However, a comprehensive genome-wide identification of the KNOX genes in Moso bamboo (Phyllostachys edulis), the fastest growing plant, has not yet been conducted, and the specific biological functions of this family remain unknown. RESULTS: The expression profiles of 24 KNOX genes, divided into two subfamilies, were determined by integrating Moso bamboo genome and its transcriptional data. The KNOX gene promoters were found to contain several light and stress-related cis-acting elements. Synteny analysis revealed stronger similarity with rice KNOX genes than with Arabidopsis KNOX genes. Additionally, several conserved structural domains and motifs were identified in the KNOX proteins. The expansion of the KNOX gene family was primarily regulated by tandem duplications. Furthermore, the KNOX genes were responsive to naphthaleneacetic acid (NAA) and gibberellin (GA) hormones, exhibiting distinct temporal expression patterns in four different organs of Moso bamboo. Short Time-series Expression Miner (STEM) analysis and quantitative real-time PCR (qRT-PCR) assays demonstrated that PeKNOX genes may play a role in promoting rapid shoot growth. Additionally, Gene Ontology (GO) and Protein-Protein Interaction (PPI) network enrichment analyses revealed several functional annotations for PeKNOXs. By regulating downstream target genes, PeKNOXs are involved in the synthesis of AUX /IAA, ultimately affecting cell division and elongation. CONCLUSIONS: In the present study, we identified and characterized a total of 24 KNOX genes in Moso bamboo and investigated their physiological properties and conserved structural domains. To understand their functional roles, we conducted an analysis of gene expression profiles using STEM and RNA-seq data. This analysis successfully revealed regulatory networks of the KNOX genes, involving both upstream and downstream genes. Furthermore, the KNOX genes are involved in the AUX/IAA metabolic pathway, which accelerates shoot growth by influencing downstream target genes. These results provide a theoretical foundation for studying the molecular mechanisms underlying the rapid growth and establish the groundwork for future research into the functions and transcriptional regulatory networks of the KNOX gene family.

Plant growth promotion and biocontrol properties of a synthetic community in the control of apple disease.

BACKGROUND: Apple Replant Disease (ARD) is common in major apple-growing regions worldwide, but the role of rhizosphere microbiota in conferring ARD resistance and promoting plant growth remains unclear. RESULTS: In this study, a synthetic microbial community (SynCom) was developed to enhance apple plant growth and combat apple pathogens. Eight unique bacteria selected via microbial culture were used to construct the antagonistic synthetic community, which was then inoculated into apple seedlings in greenhouse experiments. Changes in the rhizomicroflora and the growth of aboveground plants were monitored. The eight strains, belonging to the genera Bacillus and Streptomyces, have the ability to antagonize pathogens such as Fusarium oxysporum, Rhizoctonia solani, Botryosphaeria ribis, and Physalospora piricola. Additionally, these eight strains can stably colonize in apple rhizosphere and some of them can produce siderophores, ACC deaminase, and IAA. Greenhouse experiments with Malus hupehensis Rehd indicated that SynCom promotes plant growth (5.23%) and increases the nutrient content of the soil, including soil organic matter (9.25%) and available K (1.99%), P (7.89%), and N (0.19%), and increases bacterial richness and the relative abundance of potentially beneficial bacteria. SynCom also increased the stability of the rhizosphere microbial community, the assembly of which was dominated by deterministic processes (|ß NTI| > 2). CONCLUSIONS: Our results provide insights into the contribution of the microbiome to pathogen inhibition and host growth. The formulation and manipulation of similar SynComs may be a beneficial strategy for promoting plant growth and controlling soil-borne disease.

Planting density effect on poplar growth traits and soil nutrient availability, and response of microbial community, assembly and function.

BACKGROUND: The interaction between soil characteristics and microbial communities is crucial for poplar growth under different planting densities. Yet, little is understood about their relationships and how they respond to primary environmental drivers across varying planting densities. RESULTS: In this study, we investigated poplar growth metrics, soil characteristics, and community assembly of soil bacterial and fungal communities in four poplar genotypes (M1316, BT17, S86, and B331) planted at low, medium, and high densities. Our findings reveal that planting density significantly influenced poplar growth, soil nutrients, and microbial communities (P < 0.05). Lower and medium planting densities supported superior poplar growth, higher soil nutrient levels, increased microbial diversity, and more stable microbial co-occurrence networks. The assembly of bacterial communities in plantation soils was predominantly deterministic (ßNTI < -2), while fungal communities showed more stochastic assembly patterns (-2 < ßNTI < 2). Soil available phosphorus (AP) and potassium (AK) emerged as pivotal factors shaping microbial communities and influencing bacterial and fungal community assembly. Elevated AP levels promoted the recruitment of beneficial bacteria such as Bacillus and Streptomyces, known for their phosphate-solubilizing abilities. This facilitated positive feedback regulation of soil AP, forming beneficial loops in soils with lower and medium planting densities. CONCLUSIONS: Our study underscores the critical role of planting density in shaping soil microbial communities and their interaction with poplar growth. This research carries significant implications for enhancing forest management practices by integrating microbiological factors to bolster forest resilience and productivity.