Kiwifruit bacterial canker, caused by Pseudomonas syringae pv. actinidiae (Psa), is a significant threat to the kiwifruit industry.  The two-component signaling systems (TCSs) play a crucial role in regulating the virulence of P. syringae, yet their specific function in Psa remains largely unclear.  In this study, we found that disrupting the TCS RegAB (encoded by Psa_802/Psa_803) resulted in a notable increase in the virulence of P. syringae pv. actinidiae M228 (Psa M228) in host plant and hypersensitive reaction (HR) in nonhost plant.  Through comparative transcriptome analysis of the Psa M228 wild-type strain and the regA mutant, we identified the pivotal role of RegAB in controlling various physiological pathways, including the type III secretion system (T3SS), a key determinant of Psa virulence.  Additionally, we discovered that the RegA has binding sites in the promoter region of the hrpR/S, and the transcriptional level of the hrpR and other T3SS-related genes increased in the regA deletion strain relative to the Psa M228 wild-type.  The DNA-binding affinity of RegA, and therefore the repressor function, is enhanced by its phosphorylation.  Our findings unveil the function of TCS RegAB and the regulatory mechanism of T3SS by RegAB in Psa, highlighting the diverse functions of the RegAB system.

Phenotypic plasticity is a crucial adaptive strategy that allows organisms to respond to environmental changes. Many aphids have evolved mutualistic relationships with ants, whereby aphids provide honeydew in exchange for protection from natural enemies. Such ant–aphid mutualisms are often facultative and aphid colonies must often cope without ants. We show here that attendance by red imported fire ants, Solenopsis invicta, alters the within-plant distribution of cotton aphids (Aphis gossypii), resulting in fewer aphids on leaves and more on the stem, petioles, and sprouts (SPS) of cotton seedlings compared to colonies without ant attendance. The nitrogen contents in stems and sprouts were higher than in leaves, which may be a reason for the significantly higher population growth in ant-tended colonies. In contrast, exposure to the signals of a predatory ladybug, Coccinella septempunctata, resulted in a remarkably smaller aphid colony size, with lower proportions of aphids distributed on SPS, but a higher proportion on the leaves, compared to those in the predator-free colonies. In addition, ladybug predation risk is considerably higher on SPS than on leaves, and aphids showed rapid positional shifts from stems to leaves upon direct exposure to a ladybug, highlighting their ability to respond swiftly to predator presence. Our findings reveal that adaptive plasticity in aphid distribution patterns enables aphid colonies to optimize their fitness by responding to the presence of mutualistic ants or predatory threats with flexibility.

The mammary glands of dairy cows with ketosis face unique challenges, including the supraphysiological circulating concentrations of free fatty acids (FFA) and apoptosis of epithelial cells.  The fact that endoplasmic reticulum (ER) stress and apoptosis are closely related processes (at least in nonruminants) suggests that mechanisms of metabolic stress-induced apoptosis in bovine mammary epithelial cells may involve the ER stress pathway.  The objective of this study was to investigate (1) the status of the ER stress pathway in mammary gland of dairy cows with ketosis, and (2) the role of ER stress in the apoptosis of bovine mammary epithelial cells challenged with high concentrations of FFA.  Ketosis or exogenous FFA activated the ER stress pathway in the mammary gland of dairy cows or MAC-T cells.  Pretreatment with the ER stress activator Tunicamycin (Tun) aggravated ER stress and apoptosis in MAC-T cells induced by FFA.  However, ER stress inhibitor Tauroursodeoxycholate (TUDCA) attenuated ER stress induced by FFA and also attenuated the apoptosis in MAC-T cells.  In conclusion, the data confirmed that FFA induced apoptosis of bovine mammary epithelial cells in dairy cows with ketosis via ER stress signaling.  Thus, timely resolution of ER stress may help counteract the negative effects of ketosis on the mammary gland.

Detecting keypoints in dairy cows aims to locate and track the motion trajectories of the body’s joints, which plays a crucial role in behavior analysis and lameness detection.  However, real farming scenarios, characterized by occlusions and large variations in object scale may result in poor detection results.  Therefore, we introduce the atrous spatial pyramid pooling (ASPP) module into the shallow layers network of ResNet101, designed to improve the multi-scale feature extraction capability of the model.  The ASPP module enhances the robustness of recognition for different dimensional sizes and occluded keypoints using different dilatation rates in the parallel atrous convolutional layers to expand the model’s receptive field.  Furthermore, seven types of motion features, including tracking up, gait symmetry, step height balance, motion speed variability, head swing amplitude, head-neck slope and back curvature are extracted simultaneously by monitoring and tracking the motion trajectory of distinct keypoints.  Several of these features represent innovative extraction models and attributes, first proposed in this study.  Multiple models are trained and tested on datasets containing 2,385 frames for ablation experiments.  The experiments show that, in comparison with the ResNet50, MobileNet_v2_1.0, and EfficientNet-b0 backbone networks, the training error and test error of ResNet101 are reduced by 4.04–30.12 pixels and 3.81–28.14 pixels.  Therefore, ResNet101 is used as the benchmark for subsequent model improvement by adding the ASPP module.  The training error and test error of the ResNet101-ASPP network are reduced by 0.27 and 0.24 pixels, respectively, compared to the benchmark network.  The prediction confidence improves by 1.65–2.50% at three different dairy cow object scales. In addition, the keypoints under different occlusion conditions improve considerably, especially for small-scale keypoints, demonstrating the capability of the ASPP module for multi-scale feature extraction.  By analyzing the distribution of the seven features and health, mild lameness, and severe lameness in dairy cows, it is shown that all the different features play an important role in distinguishing between different levels of lameness.

NADC34-like porcine reproductive and respiratory syndrome virus (PRRSV) has been circulating in China for several years and became the dominant field strain in some provinces.  Current commercial vaccines could not provide complete cross-protection to NADC34-like PRRSV infection, which led to huge economic losses on pig farms.  Co-infections of NADC34-like PRRSV with some other PRRSV strains are commonly found in many clinical cases, and successful isolation of NADC34-like PRRSV strain from the clinical samples has been a challenge to study its biological characters and perform animal experiments to evaluate its pathogenicity.  In this study, we constructed a NADC34-like PRRSV infectious clone derived from the isolated JS2021NADC34 PRRSV strain using the reverse genetics technique and investigated its virulence and pathogenicity for nursery pigs.  The rescued (rNADC34) strain could proliferate well in porcine alveolar macrophages (PAMs), and the viral copy number and titers were comparable to parental strain.  For pathogenicity, the rNADC34 strain-infected pigs showed high body temperature and body weight loss.  The histopathological results presented interstitial pneumonia and severe hemorrhage, infiltration of neutrophils and lymphocyte in lungs, lymph nodes, and tonsils.  The viral proteins were also detectable in rNADC34 strain-infected pigs using immunohistochemistry staining.  Moreover, the trends of PRRSV-specific antibody and viremia in PRRSV rNADC34-infected pigs were similar with the parental strain-infected pigs.  These data indicated that rNADC34 strain manifested strong virulence and high pathogenicity for nursery pigs.

Tick-borne encephalitis (TBE) is an important zoonotic viral disease transmitted by ticks.  In recent decades, global climate change has increased human exposure to ticks, and mortality rate have gradually risen.  Effective vaccines are essential for controlling TBE as specific antiviral treatment is unavailable.  Vaccine candidates based on virus-like particles (VLPs) have previously been demonstrated to be effective in eliciting excellent immune responses against influenza virus and SARS-CoV-2.  Here, we constructed TBE virus (TBEV) VLPs containing the envelope and membrane proteins derived from the Far Eastern TBEV strain (WH2012) using an insect cell-baculovirus expression system.  Induction of immune responses was investigated in mice following intramuscular injection with the TBEV VLPs vaccine candidates formulated with a combination of poly(I:C) and Montanide ISA201VG adjuvants.  Mice produced memory T-cells and serum-specific IgG antibodies that averaged up to 1:10^4.6 and remained at 1:10⁴ (mean) at 24 wk after three immunizations.  TBEV VLPs vaccine was able to provide long-term antibody protection against TBEV, making it a promising subunit vaccine candidate for this disease.

Following the implementation of China’s “Zero-Growth Action Plan on Fertilizers” in 2015, research has predominantly focused on replacing synthetic fertilizers with organic amendments to address over-fertilization concerns.  However, insufficient attention has been given to the sustainable supply capacity of soil residual nutrients accumulated from previous over-fertilization.  To investigate the transformation dynamics and supply capacity of residual nutrients during crop production, a six-year field experiment was conducted in the dryland wheat growing region of China’s Loess Plateau.  Five treatments were established: farmer’s fertilization (FF), regulated fertilization (RF), regulated fertilization without N (RF-N), regulated fertilization without P (RF-P), and regulated fertilization without K (RF-K).  The study examined wheat yield formation, variations and stability of soil N, P, and K fractions, and their correlations with yield.  Results indicated that wheat yield sensitivity to nutrient deficiency followed the sequence N>P>K.  During the six-year period, the average yield under RF-N decreased by 22.0% compared to RF, showing statistical significance (P<0.05).  Mineral N, light fraction organic N (LFON), and heavy fraction organic N (HFON) in RF-N showed progressive decline relative to RF and initial 2018 levels.  Dissolved organic N (DON) and easily oxidizable organic N (EON) in RF-N initially decreased but subsequently increased due to N fraction transformations.  Under RF-P, H₂O-P, NaHCO₃-P, and NaOH-P levels decreased by 40.0, 51.5, and 10.3% respectively (P<0.05) compared to the RF treatment, while HCl-P, residual P, and total P (TP) remained stable.  The absence of K application (RF-K) reduced water-soluble K (WSK) by 10.9% (P<0.05), whereas exchangeable K (EK), non-exchangeable K (NEK), mineral K (MK), and total K (TK) showed no significant changes compared to the RF treatment.  These findings demonstrated that the soil nitrogen pool exhibits lower stability compared to phosphorus and potassium pools during continuous residual nutrient supply.  Notably, NO₃-N and LFON significantly influenced spike number and kernels per spike, driving yield formation.  This research advances our understanding of sustained residual nutrient supply capacity in soil and provides theoretical foundations for optimizing fertilization strategies in dryland agroecosystems.

Root exudates serve a vital function in recruiting beneficial phosphate-solubilizing bacteria (PSB), thereby enhancing plant adaptation to phosphorus (P) deficiency.  The C2H2-type zinc finger transcription factor STOP1 (sensitive to proton rhizotoxicity 1) regulates root organic acid (OA) exudation in plants.  However, the impact of STOP1-regulated root OA exudation on rhizosphere microbial composition remains unexplored.  This study revealed enhanced vegetation properties of soybean with higher P content in P-rich soils, while rhizosphere organic acid concentrations were elevated in P-poor soils.  The soybean genotype YC03-3 in P-deficient soils specifically recruited three PSB in acid soils: Gammaproteobacteria_Incertae_Sedis, KF_JG30_C25, and Solirubrobacterales.  These PSB abundances correlated positively with rhizosphere oxalate and citrate concentrations.  Under P-sufficient conditions, GmSTOP1-3 overexpression in soybean plants increased oxalate and citrate exudation compared to YCO3-3 wild type (WT), leading to preferential colonization by the same three PSB species naturally present in P-deficient WT rhizosphere.  The population dynamics of these PSB demonstrated strong positive correlations with the abundance of key genes involved in P cycling, particularly those governing acid/alkaline phosphatase activities and organic-P mineralization.  Given the phosphate starvation-enhanced expression pattern of GmSTOP1-3, the findings indicate that specific PSB recruitment for organic-P remobilization in soybean rhizosphere depends on GmSTOP1-3-mediated oxalate and citrate exudation in P-deficient acid soils.  This research establishes GmSTOP1-3 as a crucial regulator of rhizosphere microbiome assembly and P-acquisition efficiency in acid soils.

Soil microbial-metabolite interactions influence crop productivity, yet their responses to long-term nutrient management in legume systems warrant further investigation.  This study examined how fertilization and Bradyrhizobium inoculation reshape soybean rhizosphere fungal-metabolite networks to improve soil health.  Through a decade-long field trial utilizing internal transcribed spacer (ITS) sequencing and liquid chromatography-mass spectrometry (LC-MS) metabolomics, four treatments were evaluated: no fertilizer application (CK); phosphorus and potassium fertilization (PK); PK chemical fertilizers combined with urea (PK+N); PK fertilization with Bradyrhizobium japonicum 5821 inoculation (PK+R).  Results indicated that nitrogen fertilization increased fungal diversity at maturity and enhanced co-occurrence network complexity (displaying the highest node and edge counts), while Bradyrhizobium inoculation promoted stochastic assembly.  Soil fungi exhibited notable correlations with 3-hydroxymethylantipyrine, chrysophanol, 3,7-dihydroxyflavone and triethylamine.  Metabolite profiling revealed nitrogen suppression of stress-resistant flavonoids (3-hydroxymethylantipyrine, chrysophanol, 3,7-dihydroxyflavone), whereas Bradyrhizobium enhanced these key metabolites.  KEGG enrichment identified tryptophan and caffeine metabolism as central during flowering–podding stage, coordinating nitrogen assimilation and defense responses.  Additionally, the key metabolites correlated significantly with soil total nitrogen, organic matter, and available nitrogen.  These findings reveal that Bradyrhizobium acts synergistically with fertilization to activate fungal-driven metabolic pathways, offering a microbiome-based approach to enhance nitrogen efficiency and reduce agrochemical dependency in soybean systems.

The combined implementation of intercropping systems and arbuscular mycorrhizal fungi (AMF) inoculation represents a promising phytoremediation strategy for heavy metal-contaminated farmland, providing both ecological and economic benefits.  However, additional research is necessary to understand the influence of AMF and intercropping on Cd bioavailability.  This study examines the synergistic effects of maize–soybean intercropping and AMF inoculation on crop growth, cadmium (Cd) allocation patterns, and rhizosphere soil dynamics through comprehensive field and pot experiments.  Field trials revealed significant yield advantages in maize–soybean intercropping systems, with land equivalent ratios (LERs) of 1.62 (common maize) and 1.64 (sweet maize).  Intercropping decreased soybean Cd accumulation across all tissues, notably in grains (42.8% reduction), while maintaining maize grain Cd concentrations below China’s food safety threshold (0.20 mg kg^–1).  The metal removal equivalent ratio (MRER) achieved 1.33–1.38 in field conditions, validating intercropping’s dual advantage in productivity and Cd phytoextraction.  Pot experiments indicated the AMF-inoculated intercropping system (IN+A) increased maize yield by 16.4% while reducing Cd accumulation in both crops, with grain concentrations meeting safety standards.  Rhizosphere analysis demonstrated IN+A treatment substantially improved soil health indicators: 34.5% reduction in bioavailable Cd, elevated pH, decreased redox potential (Eh), and enhanced catalase activity.  AMF colonization rates were 2.2–4.3 times higher in inoculated treatments (11.5–14.0%) vs. controls (3.2–5.3%).  These results establish that AMF-enhanced legume–cereal intercropping reduces Cd bioavailability through soil alkalinization (pH increase) coupled with redox potential reduction, and metal allocation plasticity redirecting Cd to root tissues.  This interaction between microbial symbiosis and plant community design stabilizes Cd in soils while maintaining crop safety (grain Cd<0.20 mg kg^–1), establishing an ecoengineering approach for contaminated farmland remediation.