Bacteria play critical roles in regulating soil phosphorus (P) cycling.  The effects of interactions between crops and soil P-availability on bacterial communities and the feedback regulation of soil P cycling by the bacterial community modifications are poorly understood.  Here, six soybean (Glycine max) genotypes with differences in P efficiency were cultivated in acidic soils with long-term sufficient or deficient P-fertilizer treatments.  The acid phosphatase (AcP) activities, organic-P concentrations and associated bacterial community compositions were determined in bulk and rhizosphere soils.  The results showed that both soybean plant P content and the soil AcP activity were negatively correlated with soil organic-P concentration in P-deficient acidic soils.  Soil P-availability affected the ɑ-diversity of bacteria in both bulk and rhizosphere soils.  However, soybean had a stronger effect on the bacterial community composition, as reflected by the similar biomarker bacteria in the rhizosphere soils in both P-treatments.  The relative abundance of biomarker bacteria Proteobacteria was strongly correlated with soil organic-P concentration and AcP activity in low-P treatments.  Further high-throughput sequencing of the phoC gene revealed an obvious shift in Proteobacteria groups between bulk soils and rhizosphere soils, which was emphasized by the higher relative abundances of Cupriavidus and Klebsiella, and lower relative abundance of Xanthomonas in rhizosphere soils.  Among them, Cupriavidus was the dominant phoC bacterial genus, and it was negatively correlated with the soil organic-P concentration.  These findings suggest that soybean growth relies on organic-P mineralization in P-deficient acidic soils, which might be partially achieved by recruiting specific phoC-harboring bacteria, such as Cupriavidus.

The two-spotted spider mite, Tetranychus urticae Koch, is one of the most harmful pests in many agroecosystems worldwide.  To effectively manage this pest, there is an urgent need to develop novel bio-active acaricides that support integrated pest management strategies targeting T. urticae.  In this study, we explored the acaricidal effects of xenocoumacin 1 (Xcn1) on T. urticae and its predator Neoseiulus californicus using the highly purified compound.  Xcn1 was extracted and purified from the cell-free supernatant of the Xenorhabdus nematophila CB6 mutant constructed by the easy promoter activated compound identification (easyPACId) method.  When the concentration of Xcn1 exceeded 100 μg mL^–1, the survival rate of spider mite adults declined to below 40% and the fecundity was decreased by 80% at six days post-application.  At concentrations of 25 and 50 μg mL^–1, Xcn1 significantly impeded spider mite development by inhibiting the molt.  However, neither concentration had any adverse effects on the survival or reproduction of the predatory mite N. californicus.  The results from laboratory and semi-field experiments consistently demonstrated the effectiveness of the antimicrobial metabolite Xcn1 in controlling pest mites at both the molecular and physiological levels.  Our study offers a promising possibility that combines the compatible biocontrol agents of Xcn1 and predatory mites for integrated pest mite control.

Fusarium graminearum, the primary pathogenic fungus responsible for Fusarium head blight (FHB) in wheat, secretes abundant chemical compounds that interact with host plants.  In this study, a secreted protein FgHrip1, isolated from the culture filtrate of F. graminearum, was found to induce typical cell death in tobacco.  The FgHrip1 gene was then cloned and expressed in Escherichia coli.  Further bioassay analysis showed that the recombinant FgHrip1 induced early defense induction events, such as reactive oxygen species (ROS) production, callose deposition, and up-regulation of defense-related genes in tobacco.  Furthermore, FgHrip1 significantly enhanced immunity in tobacco seedlings against Pseudomonas syringae pv. tabaci 6605 (Pst. 6605) and tobacco mosaic virus (TMV).  FgHrip1-treated wheat spikes also exhibited defense-related transcript accumulation and developed immunity against FHB infection.  Whereas the expression of FgHrip1 was induced during the infection process, the deletion of the gene impaired the virulence of F. graminearum.  Our results suggest that FgHrip1 triggers immunity and induces disease resistance in tobacco and wheat, thereby providing new insight into strategy for biocontrol of FHB.

Rice false smut, caused by Ustilaginoidea virens, is a devastating disease that greatly reduces rice yield and quality.  However, controlling rice false smut disease is challenging due to the unique infection mode of U. virens.  Therefore, there is a need for early diagnosis and monitoring techniques to prevent the spread of this disease.  Lateral flow strip-based recombinase polymerase amplification (LF-RPA) overcomes the limitations of current U. virens detection technologies, which are time-consuming, require delicate equipment, and have a high false-positive rate.  In this study, we used a comparative genomics approach to identify Uv_3611, a specific gene of U. virens, as the target for the LF-RPA assay.  The designed primers and probe efffectively detected the genomic DNA (gDNA) of U. virens and demonstrated no cross-reactivity with related pathogens.  Under optimal conditions, the LF-RPA assay demonstrated a sensitivity of 10 pg of U. virens gDNA.  Additionally, by incorporating a simplified PEG-NaOH method for plant DNA extraction, the LF-RPA assay enabled the detection of U. virens in rice spikelets within 30 min, without the need for specialized equipment.  Furthermore, the LF-RPA assay successfully detected U. virens in naturally infected rice and seed samples in the field.  Therefore, the LF-RPA assay is sensitive, efficient, and convenient, and could be developed as a kit for monitoring rice false smut disease in the field.

Xenocoumacins （Xcns）, the major antimicrobial natural products produced by Xenorhabdus nematophila, have gained widespread attention for their potential application in crop protection. However, the regulatory mechanisms involved in the biosynthesis of Xcns remain poorly understood. In this study, we identified 21 potential two-component systems (TCSs) in X. nematophila CB6 by bioinformatic analysis. Among them, the response regulators (RRs) GlrR and ArcA were proven to positively regulate the production of Xcns based on gene deletion and complementation experiments. In addition, our results showed that GlrR played an important role in cell growth, while ArcA was involved in both cell morphology and growth. Using a variety of molecular biological and biochemical techniques, we found that GlrR controlled the Xcns biosynthesis by indirectly regulating the expression levels of the biosynthetic gene cluster (BGC). ArcA directly binded to the promoter regions of xcnA and xcnB to regulate the transcription of the Xcns BGC, and the binding sites were also identified. This study provides valuable insights into the regulatory network of Xcns biosynthesis, which will contribute to the construction of a high-yielding strain.

Salt stress is a major constraint to crop productivity and quality.  The limited availability of salt-tolerant genes poses significant challenges to breeding programs aimed at enhancing salt tolerance. Sorghum displays a remarkable ability to withstand saline conditions; therefore, elucidating the genetic underpinnings of this trait is crucial.  This study entailed a comprehensive resequencing of 186 sorghum accessions to perform a genome-wide association study (GWAS) focusing on relative root length (RL) and root fresh weight (RFW) under salt stress conditions. We identified eight candidate genes within a co-localized region, among which SbTEF1—a gene encoding a transcription elongation factor protein—was deemed a potential candidate due to its annotation and expression pattern alterations under salt stress.  Haplotype analysis, gene cloning, linkage disequilibrium (LD) analysis, and allele effect analysis revealed that PAV284, located in the promoter region of SbTEF1, modulated gene expression under salt stress, which, in turn, influenced sorghum seedlings' salt tolerance.  PAV284 holds promise as a genetic marker for the selection of salt-tolerant germplasm via marker-assisted breeding, enhancing the development of salt-tolerant sorghum cultivars.

Drought caused by extreme climate change has become more severe and unpredictable, causing imperceptible effects on leaf photosynthesis in foxtail millet.  To investigate the damage, we performed light drought (LD) and heavy drought (HD) treatments at both the elongation (Y) and booting stages to obtain a comprehensive understanding of the morphological, anatomical, physiological, transcriptome, and metabolome levels.  Under drought stress, the length and area of leaves decreased, especially during the HD treatment at the booting stage.  The number of mesophyll cells and the area of large vascular bundles were both decreased under LD and HD treatments at the booting stage, as well as with more blurring vascular bundle structure and Kranz anatomy.  However, these numbers decreased but with no significance under Y-LD and Y-HD treatments at the elongation stage.  The net photosynthetic rate, stomatal conductivity, transpiration rate, and intercellular CO₂ concentration significantly decreased at the booting stage.  In addition, the efficiency of electron transfers in photosystem II (PS II) decreased.  Conjunction analyses of the transcriptome and metabolome were utilized to uncover the underlying mechanism at the booting stage.  The results showed that there was no common differentially enriched pathway in the transcriptome and metabolome under LD treatment but thirty-two pathways were enriched in both the transcript and metabolome under HD treatment.  Among these, three pathways arginine, proline metabolism, tyrosine metabolism, ubiquinone, and other terpenoid-quinone biosynthesis pathways were differentially enriched in both the transcript and metabolome.  The accumulation of Homogentisate, Salidroside, Homoprotocatechuate, L-DOPA, Tyramine, and L-Tyrosine increased under drought stress.  Although genes related to PSII and the Calvin cycle were slightly up-regulated under LD conditions, they were down-regulated under HD condition.  The metabolites of Ribose-5P, Glycerate-3P, D-Fructosel 1,6P₂, and D-Fructose-6P were all decreased in both the LD and HD treatments, especially D-Fructose-6P, confirming that drought stress had a negative effect on the Calvin cycle.  The results revealed that regardless of the severity of drought, photosynthetic function was compromised not only at the morphological and anatomical levels but also in terms of impaired ATP synthase and inhibited photosynthetic CO₂ assimilation.

The H9N2 subtype avian influenza virus (AIV) hemagglutinin (HA) protein is a major immunogen in which HA1 is a genetic variant and HA2 is relatively conserved. Identifying broad-spectrum antigen epitopes targeting HA1 is crucial for vaccine design and detection. Based on the phylogenetic and serological analyses, we identified 2 antigenic groups and 3 representative viruses: A/chicken/Jiangsu/JY040218C/2019, A/pigeon/Jiangsu/JY020616/2019, and A/chicken/Jiangsu/WX090312/2018. An overlapping peptide library was synthesized using HA1 amino acid sequences of the viruses as templates. Through peptide scanning of the sera against different strains of H9N2 subtype AIV, we identified peptides from 4 regions (H9-2/3, H9-20/21, H9-26, and H9-29/30/31) that demonstrated broad-spectrum reactivity. Immunological assay results demonstrated that H9-21 (²¹⁹RIFKPLIGPRPLVNGLMGRI²³⁹), H9-26 (²⁶⁹SGESHGRILKTDLKMGSCTV²⁸⁹), and H9-30 (³⁰⁹YAFGNCPKYI GVKSLKLAVG³²⁹) effectively induced antibody generation and conferred partial protective efficacy against the parent virus JY040218C. The results of lymphocyte proliferation and ELISpot assays indicated that peptides H9-15 (¹⁵⁹MRWLTQKNNAYPTQDAQYTN¹⁷⁹), H9-22 (²²⁹PLVNGLMGRINYYWSVLKP G²⁴⁹), and H9-23 (²³⁹NYYWSVLKPGQTLRIKSDGN²⁵⁹) could effectively stimulate the expression of interferon-gamma in peripheral blood lymphocytes of chickens immunized against different strains of H9N2 AIV. Collectively, 5 novel cell epitopes H9-15, H9-22, H9-23, H9-26, and H9-30, including the best B cell epitope H9-26 and the best T cells epitope H9-22, were identified that could be targeted for vaccine design or detection approaches against H9N2 AIVs

Streptococcus suis is a significant zoonotic agent affecting both human and pig health and poses a substantial public health concern. The pathogenicity of S. suis is intricately linked to its ability to form biofilms and express virulence factors, which are regulated by the LuxS/AI-2 quorum sensing (QS) system. Herein, we uncover a novel therapeutic avenue by demonstrating that 5-fluorouracil (5-FU), an FDA-approved anti-cancer agent, effectively mitigates biofilm formation and attenuates the virulence of S. suis. Mechanistically, we observe a significant reduction in capsular polysaccharide and extracellular polysaccharide production upon 5-FU treatment, elucidating a potential mechanism for biofilm weakening. Additionally, 5-FU down-regulates virulence traits, diminishing S. suis's ability to adhere to host cells and evade phagocytosis. Crucially, our study identifies the thymidylate synthase regulatory gene thyA as a key mediator of 5-FU's effects on the LuxS/AI-2 QS system. Virtual molecular docking and gene knockout experiments provide compelling evidence that 5-FU modulates the LuxS/AI-2 QS system by targeting thyA. In vivo experiments further validate the therapeutic potential of 5-FU, showcasing a significant reduction in bacterial load and mitigation of tissue damage in a mouse model. In conclusion, our investigation unveils 5-FU as a potent disruptor of S. suis's biofilm formation and virulence, offering a promising avenue for the control of this devastating pathogen.

Maize/soybean intercropping systems are commonly used in developing countries, but few studies have been performed to elucidate the differences in nutrient efficiency and rhizosphere microbiome, especially when maize is intercropped with different soybean varieties. In this study, field experiments were conducted to compare the growth and yield of two soybean (Glycine max) varieties, BD2 and YC03-3, and one maize (Zea mays) variety, Huazhen, in mono-cropped and intercropped cultures. The plant biomass and N content of both crops in BD2/maize intercropping were significantly improved compared to their monoculture, but no such effects were observed in the plants of YC03-3/maize intercropping. The yield of BD2 intercropped with maize exhibited a 37.5% increment above that of BD2 in monoculture. Moreover, 19.2-29.1% longer root length of maize and 19.0-39.4% larger root volume of BD2 were observed in BD2/maize intercropping than in monoculture, but no growth advantage was observed in YC03-3/maize intercropping. Maize showed root avoidance when intercropped with BD2, but space competition when intercropped with YC03-3. 16S rRNA amplicon sequencing showed that compared with the monoculture system, rhizobacteria community composition in BD2/maize intercropping changed more significantly than that of the YC03-3/maize intercropping system. In BD2/maize intercropping, most of the rhizobacteria community biomarker bacteria of BD2 were positively correlated with plant biomass, as well as plant P and N content. Maize tended to recruit Rhizobiales and Proteobacteria, which showed positive correlation with plant biomass and N content, respectively, as well as soil available N. In conclusion, soybean varieties determined the advantages of maize/soybean intercropping through root-root interactions and modification of rhizobacteria communities. Our insight emphasizes a linkage between root traits and the rhizobacteria community, which shows the importance of optimizing intercropping systems by selection of appropriate crop varieties.

Wheat-maize rotation is a widely used planting pattern in oasis irrigated areas in northwest China.  Although this planting pattern has the advantage of breaking the barrier of continuous cropping to some extent, it also has some problems such as large evaporation and prominent soil degradation during fallow period, which seriously restricts the improvement of crop yield.  Planting green manure (GM) after wheat and returning it to field can effectively improve soil physicochemical properties, regulate photosynthetic characteristics of subsequent crops and promote crop yield.  However, the photosynthetic physiological mechanism of crop yield improvement under different green manure return methods (GMRM) is still unclear.  Therefore, by exploring the relationships among soil moisture and temperature environment, maize root structure, photosynthetic characteristics, fluorescence characteristics and yield under different GMRM, this study aims to provide theoretical basis for clarifying the photosynthetic physiological mechanism of GMRM to improve maize yield.  A three-year field experiment was conducted at a research station in the Shiyang River Basin (Gansu, China).  Five treatments were involved in this study: (i) conventional tillage without GM (CT), (ii) no-tillage with total GM mulching (NTG), (iii) no-tillage with removal of aboveground GM (NT), (iv) tillage with total GM incorporation (TG), and (v) tillage with only root incorporation (T).  Results showed that the NTG and TG significantly increased soil water content (SWC) in 0-110 cm soil layer, soil temperature (ST) of maize seedling (V3) to jointing stage (V6), canopy cover (CC), leaf stay-greenness (SG), root length (RL), net photosynthetic rate (P_n), transpiration rate (T_r), actual photochemical efficiency of PSII (ՓPSII), maize biomass and grain yield (GY) compared with CT.  In addition, NTG and TG significantly decreased ST of maize big trumpet stage (V12) to blister stage (R2), and dissipation of excess energy (NPQ) compared with CT.  The GM return to field could improve root structure and canopy coverage of maize mainly by improving soil water content.  The optimization of maize root structure and canopy coverage increased maize chlorophyll content (SPAD) value and promoted P_n.  The increase of P_n inhibits the increase of NPQ, thus promoting ՓPSII.  The increase of ՓPSII promoted the increase of maize biomass, and finally realized the increase of maize GY.