Organoid forming potential as complementary parameter for accurate evaluation of breast cancer neoadjuvant therapeutic efficacy.

BACKGROUND: 13-15% of breast cancer/BC patients diagnosed as pathological complete response/pCR after neoadjuvant systemic therapy/NST suffer from recurrence. This study aims to estimate the rationality of organoid forming potential/OFP for more accurate evaluation of NST efficacy. METHODS: OFPs of post-NST residual disease/RD were checked and compared with clinical approaches to estimate the recurrence risk. The phenotypes of organoids were classified via HE staining and ER, PR, HER2, Ki67 and CD133 immuno-labeling. The active growing organoids were subjected to drug sensitivity tests. RESULTS: Of 62 post-NST BC specimens, 24 were classified as OFP-I with long-term active organoid growth, 19 as OFP-II with stable organoid growth within 3 weeks, and 19 as OFP-III without organoid formation. Residual tumors were overall correlated with OFP grades (P < 0.001), while 3 of the 18 patients (16.67%) pathologically diagnosed as tumor-free (ypT0N0M0) showed tumor derived-organoid formation. The disease-free survival/DFS of OFP-I cases was worse than other two groups (Log-rank P < 0.05). Organoids of OFP-I/-II groups well maintained the biological features of their parental tumors and were resistant to the drugs used in NST. CONCLUSIONS: The OFP would be a complementary parameter to improve the evaluation accuracy of NST efficacy of breast cancers.

High-density mapping of durable and broad-spectrum stripe rust resistance gene Yr30 in wheat.

KEY MESSAGE: The durable stripe rust resistance gene Yr30 was fine-mapped to a 610-kb region in which five candidate genes were identified by expression analysis and sequence polymorphisms. The emergence of genetically diverse and more aggressive races of Puccinia striiformis f. sp. tritici (Pst) in the past twenty years has resulted in global stripe rust outbreaks and the rapid breakdown of resistance genes. Yr30 is an adult plant resistance (APR) gene with broad-spectrum effectiveness and its durability. Here, we fine-mapped the YR30 locus to a 0.52-cM interval using 1629 individuals derived from residual heterozygous F5:6 plants in a Yaco"S"/Mingxian169 recombinant inbred line population. This interval corresponded to a 610-kb region in the International Wheat Genome Sequencing Consortium (IWGSC) RefSeq version 2.1 on chromosome arm 3BS harboring 30 high-confidence genes. Five genes were identified as candidate genes based on functional annotation, expression analysis by RNA-seq and sequence polymorphisms between cultivars with and without Yr30 based on resequencing. Haplotype analysis of the target region identified six haplotypes (YR30_h1-YR30_h6) in a panel of 1215 wheat accessions based on the 660K feature genotyping array. Lines with YR30_h6 displayed more resistance to stripe rust than the other five haplotypes. Near-isogenic lines (NILs) with Yr30 showed a 32.94% higher grain yield than susceptible counterparts when grown in a stripe rust nursery, whereas there was no difference in grain yield under rust-free conditions. These results lay a foundation for map-based cloning Yr30.

Study on a Highly Thermostable Dy3+-Activated Borophosphate Phosphor.

Constructing a phosphor with multifunctional applications is an imperative challenge. Especially, highly thermostable luminescence of phosphor is indispensable for stable white-light-emitting diodes (LEDs). Nevertheless, good thermal quenching resistance behavior is unfavorable for a fluorescence intensity ratio (FIR)-based optical temperature sensor. Herein, a highly thermostable Ba3(ZnB5O10)PO4 (BZBP)-based phosphor is successfully achieved via replacing Ba2+ with Dy3+, demonstrating simultaneously promising lighting and thermometry utilizations. Under the excitation of 350 nm, the title phosphor only loses 12% of the initial intensity when the temperature is up to 473 K, ensuring sufficient luminescence thermostability for white-LED lighting. The white-LED device fabricated using the title phosphor emits high-quality white light with a high color rendering index (Ra = 93) and low correlated color temperature (CCT = 3996 K). Meanwhile, the yellow and blue emission intensities demonstrate a downtrend difference with rising temperature. Temperature sensing properties are assessed through FIR technology. The maximal relative sensitivity reaches as high as 0.0379 K-1 at 298 K. These results reveal that the title phosphor has a great potential for indoor lighting and thermometry applications.

Boosting the sonodynamic performance of CoBiMn-layered double hydroxide nanoparticles via tumor microenvironment regulation for ultrasound imaging-guided sonodynamic therapy.

Sonodynamic therapy (SDT), a promising strategy for cancer treatment with the ability for deep tissue penetration, has received widespread attention in recent years. Sonosensitizers with intrinsic characteristics for tumor-specific curative effects, tumor microenvironment (TME) regulation and tumor diagnosis are in high demand. Herein, amorphous CoBiMn-layered double hydroxide (a-CoBiMn-LDH) nanoparticles are presented as multifunctional sonosensitizers to trigger reactive oxygen species (ROS) generation for ultrasound (US) imaging-guided SDT. Hydrothermal-synthesized CoBiMn-LDH nanoparticles are etched via a simple acid treatment to obtain a-CoBiMn-LDH nanoparticles with abundant defects. The a-CoBiMn-LDH nanoparticles give greater ROS generation upon US irradiation, reaching levels ~ 3.3 times and ~ 8.2 times those of the crystalline CoBiMn-LDH nanoparticles and commercial TiO2 sonosensitizer, respectively. This excellent US-triggered ROS generation performance can be attributed to the defect-induced narrow band gap and promoted electrons and holes (e-/h+) separation. More importantly, the presence of Mn4+ enables the a-CoBiMn-LDH nanoparticles to regulate the TME by decomposing H2O2 into O2 for hypoxia relief and US imaging, and consuming glutathione (GSH) for protection against ROS clearance. Biological mechanism analysis shows that a-CoBiMn-LDH nanoparticles modified with polyethylene glycol can serve as a multifunctional sonosensitizer to effectively kill cancer cells in vitro and eliminate tumors in vivo under US irradiation by activating p53, apoptosis, and oxidative phosphorylation-related signaling pathways.

A MgAl-LDH-CuS nanosheet-based thermo-responsive composite hydrogel with nir-responsive angiogenesis inhibitor releasing capability for multimode starvation therapy.

The rapid proliferation of tumors is highly dependent on the nutrition supply of blood vessels. Cutting off the nutrient supply to tumors is an effective strategy for cancer treatment, known as starvation therapy. Although various hydrogel-based biomaterials have been developed for starvation therapy through glucose consumption or intravascular embolization, the limitations of single-mode starvation therapy hinder their therapeutic effects. Herein, we propose a dual-function nutrition deprivation strategy that can block the nutrients delivery through extravascular gelation shrinkage and inhibit neovascularization through angiogenesis inhibitors based on a novel NIR-responsive nanocomposite hydrogel. CuS nanodots-modified MgAl-LDH nanosheets loaded with angiogenesis inhibitor (sorafenib, SOR) are incorporated into the poly(n-isopropylacrylamide) (PNIPAAm) hydrogel by radical polymerization to obtain the composite hydrogel (SOR@LDH-CuS/P). The SOR@LDH-CuS/P hydrogel can deliver hydrophobic SOR with a NIR-responsive release behavior, which could decrease the tumor vascular density and accelerate cancer cells apoptosis. Moreover, the SOR@LDH-CuS/P hydrogel exhibits higher (3.5 times) compressive strength than that of the PNIPAAm, which could squeeze blood vessels through extravascular gelation shrinkage. In vitro and in vivo assays demonstrate that the interruption of nutrient supply by gelation shrinkage and the prevention of angiogenesis by SOR is a promising strategy to inhibit tumor growth for multimode starvation therapy.

High-resolution fiber grating pressure sensor with in-situ calibration for deep sea exploration.

A high-resolution and wide-range pressure sensor based on π phase-shifted fiber Bragg grating (π-FBG) encapsulated with metal thin-walled cylinder is reported. The sensor has been tested with a wavelength-sweeping distributed feedback laser, photodetector and a H13C14N gas cell. To perceive temperature and pressure synchronously, a pair of π-FBGs are glued on the outer wall of the thin-walled cylinder along the circumferential direction with different angles. The interference of temperature is effectively corrected by a high-precision calibration algorithm. The reported sensor has a sensitivity of 4.42 pm/MPa, a resolution of 0.036% full scale (F.S.), and a repeatability error of 0.045% F.S. in the range of 0-110 MPa that corresponds to an ocean depth resolution of 5 m and a measurement range of eleven thousand meters to cover the deepest trench of the Ocean. The sensor features simplicity, good repeatability, and practicability.

Reduction of Rhizoctonia cerealis Infection on Wheat Through Host- and Spray-Induced Gene Silencing of an Orphan Secreted Gene.

Rhizoctonia cerealis is a soilborne fungus that can cause sharp eyespot in wheat, resulting in massive yield losses found in many countries. Due to the lack of resistant cultivars, fungicides have been widely used to control this pathogen. However, chemical control is not environmentally friendly and is costly. Meanwhile, the lack of genetic transformation tools has hindered the functional characterization of virulence genes. In this study, we attempted to characterize the function of virulence genes by two transient methods, host-induced gene silencing (HIGS) and spray-induced gene silencing (SIGS), which use RNA interference to suppress the pathogenic development. We identified ten secretory orphan genes from the genome. After silencing these ten genes, only the RcOSP1 knocked-down plant significantly inhibited the growth of R. cerealis. We then described RcOSP1 as an effector that could impair wheat biological processes and suppress pathogen-associated molecular pattern-triggered immunity in the infection process. These findings confirm that HIGS and SIGS can be practical tools for researching R. cerealis virulence genes. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Microbial Lipopeptide Supramolecular Self-Assemblies as a Methuosis-Like Cell Death Inducer with In Vivo Antitumor Activity.

Discovering new drugs and improving action mechanisms is a promising strategy to overcome chemotherapy ineffectiveness caused by cancer cell apoptosis resistance. Natural products (like cyclic lipopeptides, CLPs) are potential sources of nonapoptotic cell death inducers and can form diverse supramolecular structures, closely relating to their bioactivities. Herein, it is found for the first time that fatty chain is the key to maintain self-assembled form and antitumor activity of microbial-derived amphiphilic CLP bacillomycin Lb (B-Lb). Compared with B-Lb analogues assemblies without antitumor activity, B-Lb supramolecular self-assemblies (including nanomicelles, nanofibers, giant micrometer rods) can be generated in a multilevel and cross-scale manner and served as a methuosis-like cell death inducer triggered by cytoplasmic vacuolation through macropinocytosis in MDA-MB-231-Luc and MCF-7 cells and in vivo tumor-bearing mice. This study will promote constructing of customized CLP micro-/nanostructures with multipurposes and functions, and boost designing of new antitumor drugs as nonapoptotic cell death modulators based on structure-activity relationship.

Adsorption Thermodynamic and Kinetic Mechanism of Substrate-Induced Molecular Geometry Orientation.

N719 dye (cis-[Ru(4-carboxy-4'-carboxylate-2,2'-bipyridine)2(NCS)2]) contains two carboxylic acid/carboxylate groups and two isothiocyanato (NCS) ligands and exhibit different spatial adsorption orientations during adsorption on different substrate surfaces. However, the effect of spatially adsorption orientations on the adsorption process has been rarely reported. This paper presents a detailed study of the adsorption kinetics and thermodynamics of N719 molecules based on a quartz crystal microbalance under variable temperature conditions using TiO2 or Au substrate surfaces to induce changes in the geometrical orientation molecules. This work also reveals the adsorption properties of carboxylate groups and NCS ligands acting as anchoring groups. Research results have shown that the surface N719 molecular density of the TiO2 substrate is higher than that of the Au substrate. Adsorption kinetics have shown that the adsorption rate of N719 molecules on the Au substrate surface with NCS ligands as anchor groups is slightly higher than that of carboxylate as the anchor groups on the TiO2 substrate surface, and in the case of the former adsorption mode, the desorption is more pronounced. Under two different spatial orientation adsorption modes, both exhibit physical adsorption. The thermodynamics of molecular adsorption with different spatial orientations show that all adsorption processes are spontaneous and endothermic. This work is beneficial for understanding the mechanism of adsorption of dye molecules, dye molecule synthesis method, ligand selection, and improvement of device efficiency.

Selective colorimetric sensing of sub-nanomolar Hg2+ based on its significantly enhancing peroxidase mimics of silver/copper nanoclusters.

A simple colorimetric sensing strategy for Hg2+ ions was developed using silver/copper nanoclusters (Ag/Cu NCs) with excellent selectivity and sensitivity. Bimetallic Ag/Cu NCs were synthesized by using glutathione (GSH) as a template and sodium borohydride as a reducing agent. It was found that the peroxidase-like activity of Ag/Cu NCs was significantly enhanced in the presence of Hg2+. Therefore, a colorimetric method based on catalysis was developed to detect Hg2+ with a linear concentration range of 0.1-700 nM and a detection limit of 0.05 nM (S/N = 3). The common species have no effect on Hg2+ ion detection. Furthermore, this method is applicable to accurately detect Hg2+ in real aqueous samples and is reproducible. Therefore, owing to the merits of sensitivity, selectivity, rapid response and visual read-out, it can be promising in the development of a portable Hg2+ analyzer for on-site detection.

Alteration of the gut microbiome and immune factors of grass carp infected with Aeromonas veronii and screening of an antagonistic bacterial strain (Streptomyces flavotricini).

Aeromonas veronii is a widely distributed novel pathogen that can affect humans and animals, it can cause sepsis in fish with high mortality and serious economic losses to aquaculture. In the study, the gut microbiome of the infected and uninfected grass carp with Aeromonas veronii were analyzed probiotics and pathogenic bacteria by the Miseq high-throughput sequencing, the results showed that the infected fish were significantly higher in Proteobacteria, Firmicutes, Fusobacteria, and the immune factors in liver and kidney were up-regulated by qRT-PCR. In order to effectively inhibit the pathogen, we screened an actinomycete strain and had good antibacterial effect on Aeromonas veronii. The new antagonistic bacteria was named as Streptomyces flavotricini X101, the whole genome sequencing revealed that the metabolic process was most active. After grass carp was inoculated with the minimum inhibitory concentration of 900 µg/mL of the strain's fermentation supernatant, then Aeromonas veronii was injected, we found that the pathological symptoms such as body surface, anus and abdominal congestion were alleviated by H&E staining. Cellular experiments showed that it wasn't toxic to liver cells of grass carp. Overall, this is the first study of changes in intestinal flora, phenotype, and immune factors in grass crap infected with Aeromonas veronii, it had important theoretical significance and application value for immunization and prevention.

A comprehensive genomic and growth proteomic analysis of antitumor lipopeptide bacillomycin Lb biosynthesis in Bacillus amyloliquefaciens X030.

Lipopeptides (such as iturin, fengycin, and surfactin) from Bacillus possess antibacterial, antifungal, and antiviral activities and have important application in agriculture and pharmaceuticals. Although unremitting efforts have been devoted to improve lipopeptide production by designing gene regulatory circuits or optimizing fermentation process, little attention has been paid to utilizing multi-omics for systematically mining core genes and proteins during the bacterial growth cycle. Here, lipopeptide bacillomycin Lb from new Bacillus amyloliquefaciens X030 was isolated and first found to have anticancer activity in various cancer cells (such as SMMC-7721 and MDA-MB-231). A comprehensive genomic and growth proteomic analysis of X030 revealed bacillomycin Lb biosynthetic gene cluster, key enzymes and potential regulatory proteins (PerR, PhoP, CcpA, and CsfB), and novel links between primary metabolism and bacillomycin Lb production in X030. The antitumor activity of the fermentation supernatant supplemented with amino acids (such as glutamic acid) and sucrose was significantly increased, verifying the role of key metabolic switches in the metabolic regulatory network. Quantitative real-time PCR analysis confirmed that 7 differential expressed genes exhibited a positive correlation between changes at transcriptional and translational levels. The study not only will stimulate the deeper and wider antitumor study of lipopeptides but also provide a comprehensive database, which promotes an in-depth analysis of pathways and networks for complex events in lipopeptide biosynthesis and regulation and gives great help in improving the yield of bacillomycin Lb (media optimization, genetic modification, or pathway engineering).

Development of carbon nanotube modified cement paste with microencapsulated phase-change material for structural-functional integrated application.

Microencapsulated phase-change materials (MPCM) can be used to develop a structural-functional integrated cement paste having high heat storage efficiency and suitable mechanical strength. However, the incorporation of MPCM has been found to degrade the mechanical properties of cement based composites. Therefore, in this research, the effect of carbon nanotubes (CNTs) on the properties of MPCM cement paste was evaluated. Test results showed that the incorporation of CNTs in MPCM cement paste accelerated the cement hydration reaction. SEM micrograph showed that CNTs were tightly attached to the cement hydration products. At the age of 28 days, the percentage increase in flexural and compressive strength with different dosage of CNTs was found to be up to 41% and 5% respectively. The optimum dosage of CNTs incorporated in MPCM cement paste was found to be 0.5 wt %. From the thermal performance test, it was found that the cement paste panels incorporated with different percentages of MPCM reduced the temperature measured at the center of the room by up to 4.6 °C. Inverse relationship was found between maximum temperature measured at the center of the room and the dosage of MPCM.

AtROP1 negatively regulates potato resistance to Phytophthora infestans via NADPH oxidase-mediated accumulation of H2O2.

BACKGROUND: Small GTPases are monomeric guanine nucleotide-binding proteins. In plants, ROPs regulate plant cell polarity, plant cell differentiation and development as well as biotic and abiotic stress signaling pathways. RESULTS: We report the subcellular localization of the AtRop1 protein at the plasma membrane in tobacco epidermal cells using GFP fusions. Additionally, transient and stable expression of a dominant negative form (DN) of the Arabidopsis AtRop1 in potato led to H2O2 accumulation associated with the reduced development of Phytophthora infestans Montagne de Bary and smaller lesions on infected potato leaves. The expression of the Strboh-D gene, a NADPH oxidase homologue in potato, was analyzed by RT-PCR. Expression of this gene was maintained in DN-AtRop1 transgenic plants after infection with P. infestans. In transgenic potato lines, the transcript levels of salicylic acid (SA) and jasmonic acid (JA) marker genes (Npr1 and Lox, respectively) were analyzed. The Lox gene was induced dramatically whereas expression of Npr1, a gene up-regulated by SA, decreased slightly in DN-AtRop1 transgenic plants after infection with P. infestans. CONCLUSIONS: In conclusion, our results indicate that DN-AtROP1 affects potato resistance to P. infestans. This is associated with increased NADPH oxidase-mediated H2O2 production and JA signaling.

PAD4 Inhibitor-Functionalized Layered Double Hydroxide Nanosheets for Synergistic Sonodynamic Therapy/Immunotherapy Of Tumor Metastasis.

Sonodynamic therapy (SDT) is demonstrated to trigger the systemic immune response of the organism and facilitate the treatment of metastatic tumors. However, SDT-mediated neutrophil extracellular traps (NETs) formation can promote tumor cell spread, thus weakening the therapeutic effectiveness of metastatic tumors. Herein, the amorphous CoW-layered double hydroxide (a-CoW-LDH) nanosheets are functionalized with a peptidyl arginine deiminase 4 (PAD4) inhibitor, i.e., YW3-56, to construct a multifunctional nanoagent (a-LDH@356) for synergistic SDT/immunotherapy. Specifically, a-CoW-LDH nanosheets can act as a sonosensitizer to generate abundant reactive oxygen species (ROS) under US irradiation. After loading with YW3-56, a-LDH@356 plus US irradiation not only effectively induces ROS generation and immunogenic cell death, but also inhibits the elevation of citrullinated histone H3 (H3cit) and the release of NETs, enabling a synergistic enhancement of anti-tumor metastasis effect. Using 4T1 tumor model, it is demonstrated that combining a-CoW-LDH with YW3-56 stimulates an anti-tumor response by upregulating the proportion of immune-activated cells and inducing polarization of M1 macrophages, and inhibits immune escape by downregulating the expression of PD-1 on immune cells under US irradiation, which not only arrests primary tumor progression with a tumor inhibition rate of 69.5% but also prevents tumor metastasis with the least number of lung metastatic nodules.

Short-term efficacy and safety of neoadjuvant pyrotinib plus taxanes for early HER2-positive breast cancer: a single-arm exploratory phase II trial.

Background: The effectiveness and safety of pyrotinib have been substantiated in human epidermal growth factor receptor 2 (HER2)-positive advanced breast cancer (BC). However, the role of pyrotinib as a single HER2 blockade in neoadjuvant setting among BC patients has not been studied. The objective of this study was to evaluate the efficacy and tolerability of pyrotinib plus taxanes as a novel neoadjuvant regimen in patients with HER2-positive early or locally advanced BC. Methods: In this single-arm exploratory phase II trial, patients with treatment-naïve HER2-positive BC (stage IIA-IIIC) received pyrotinib 400 mg once daily and taxanes [docetaxel 75 mg/m2 or nanoparticle albumin-bound (nab)-paclitaxel 260 mg/m2 every 3 weeks, or paclitaxel 80 mg/m2 weekly] for a total of four 21-day cycles before surgery. Efficacy assessment was based on pathological and clinical measurements. The primary endpoint of this study was the total pathological complete response (tpCR) rate. The secondary endpoints included breast pCR (bpCR) rate, investigator-assessed objective response rate (ORR) and adverse events (AEs) profiles. Results: From 1 September 2021 to 30 December 2022, a total of 31 patients were enrolled. One patient was withdrawn due to unbearable skin rash after the second cycle of neoadjuvant therapy. The majority of the intention-to-treat (ITT) population was premenopausal (54.8%), had large tumors (90.3%) and metastatic nodes (58.1%) at diagnosis and hormone-receptor positive tumors (64.5%). Most participants used nab-paclitaxel (74.2%) and received mastectomy (67.7%) after neoadjuvant treatment. The tpCR and bpCR rates were 48.4% [95% confidence interval (CI): 30.8-66%] and 51.6% (95% CI: 34-69.2%), respectively. Grade ≥3 treatment-related AEs were observed in 16.1% (5/31) of the ITT population, including diarrhea (n=2, 6.5%), hand and foot numbness (n=1, 3.2%), loss of appetite (n=1, 3.2%), and skin rash (n=1, 3.2%). AE related dose reduction or pyrotinib interruption was not required. Conclusions: In female patients with HER2-positive non-metastatic BC, neoadjuvant pyrotinib monotherapy plus taxanes appears to show promising clinical benefit and controllable AEs [Chinese Clinical Trial Registry (ChiCTR2100050870)]. The long-term efficacy and safety of this regime warrant further verification.

Molecular and pathogenic characterization of new Xanthomonas oryzae pv. oryzae strains from the coastline region of Fangchenggang city in China.

Virulence assays and DNA polymorphism analyses were used to characterize 33 Xanthomonas oryzae pv. oryzae (Xoo) strains collected from the coastline region of Fangchenggang city in China. Two new pathogenic races (FXP1 and FXP2), were determined by leaf-clipping inoculation of 12 near-isogenic International Rice-Bacterial Blight (IRBB) rice lines, each containing a single resistance gene. Race FXP1 consisted of twenty-eight strains that were incompatible on IRBB5 and IRBB7, while race FXP2 included five strains that were incompatible on IRBB5 and IRBB7 and moderately virulent on IRBB8 containing the xa8 gene. Restriction fragment length polymorphism (RFLP) analysis revealed that each probe of avrXa10 and IS1112 resolved two haplotypes. In a dendrogram generated from the combined RFLP data, the 33 Xoo strains were resolved into two clusters. There was a weak correlation (r = 0.53) between race and haplotype. All of the rice cultivars planted in the coastline region of Fangchenggang city were susceptible to the representative Xoo strains tested above. However, we found that four rice cultivars used as breeding materials in the laboratory could fully resist infection by the Xoo strains, suggesting that the isolated Xoo strains could be used to detect resistant rice cultivars suitable for planting in the local rice field.

[Macroscopic and microscopic identification of Mongolian medicine Potentilla glabra].

OBJECTIVE: To provide the identification basis for Mongolian medicine Potentilla glabra. METHODS: Macroscopic and microscopic identification were applied to observe macroscopic, histological, superficial, and powder characteristics of its stems and leaves. RESULTS: The following characteristics were observed: The cork layer sandwiched with sclerenchyma ring which was main composed of fibers, accompanied by stone cells and large cell layer; Catheter with fiber existed in xylem; Beaded thickened anticlinal wall in leaf epidermal cell; Stomatal infinitive; Small clusters of calcium oxalate crystal and different type of leaf transverse section. CONCLUSION: These characteristics can provide evidences for the identification and quality control of Potentilla glabra.

[Effects of Phosphogypsum and Suaeda salsa on the Soil Moisture, Salt, and Bacterial Community Structure of Salinized Soil].

The improvement of saline soil is an important issue that cannot be ignored in the farmland soil environment. The change in soil salinity will inevitably affect the soil bacterial community. This experiment was based on moderately saline soil in the Hetao Irrigation Area, conducted by applying phosphogypsum (LSG), interplanting Suaeda salsa with Lycium barbarum (JP) and applying phosphogypsum and interplanting S. salsa with L. barbarum (LSG+JP),and the local unimproved soil of a L. barbarum orchard was used as the control (CK), to explore the effects of different improvement methods on soil moisture, salinity, nutrients, and bacterial community structure diversity during the growth period of L. barbarum. The results showed that compared with that under CK, the LSG+JP treatment significantly decreased the soil EC value and pH value from the flowering stage to the deciduous stage (P<0.05), with an average decrease of 39.96% and 7.25%, respectively; the LSG+JP treatment significantly increased soil organic matter (OM) and available phosphorus (AP) content during the whole growth period (P<0.05), with an average annual increase of 81.85% and 203.50%, respectively. The total nitrogen (TN) content was significantly increased in the flowering and deciduous stages (P<0.05), with an annual average increase of 48.91%. The Shannon index of LSG+JP in the early stage of improvement was increased by 3.31% and 6.54% compared with that of CK, and the Chao1 index was increased by 24.95% and 43.26% compared with that of CK, respectively. The dominant bacteria in the soil were Proteobacteria, Bacteroidetes, Actinobacteria, and Acidobacteria, and the dominant genus was Sphingomonas. Compared with that in CK, the relative abundance of Proteobacteria in the improved treatment increased by 0.50%-16.27% from the flowering stage to the deciduous stage, and the relative abundance of Actinobacteria in the improved treatment increased by 1.91%-4.98% compared with that in CK in the flowering and full-fruit stages. Redundancy analysis (RDA) results showed that pH, water content (WT), and AP were important factors affecting bacterial community composition, and the correlation heatmap showed that Proteobacteria, Bacteroidetes, and EC values were significantly negatively correlated (P<0.001); Actinobacteria and Nitrospirillum were significantly negatively correlated with EC values (P<0.01). In conclusion, the application of phosphogypsum and interplanting S. salsa with L. barbarum (LSG+JP) could significantly reduce soil salinity, increase nutrients, and improve the diversity of soil bacterial community structure, which is beneficial to the long-term improvement of saline soil in the Hetao Irrigation Area and the maintenance of soil ecological health.

[Effects of Microbial Fertilizer on Physicochemical Properties and Bacterial Communities of Saline Soil Under Brackish Water Irrigation].

The improvement of saline soil with microbial fertilizer has numerous advantages including high efficiency, green environmental protection, etc. At the same time, applying microbial fertilizer is an effective way to safely use brackish water. Based on the moderately saline soil in the Hetao irrigation area, four treatments of F1 (4500 kg·km-2), F2 (7500 kg·km-2), F3 (10500 kg·km-2), and CK without microbial fertilizer were applied under brackish water irrigation using Lycium barbarum as the indicator plants. The aim was to study the effects of different microbial fertilizer application rates on soil ions, soil moisture content, pH value, nutrients, and bacterial community in four key growth stages of L. barbarum (flowering stage, fruit expansion stage, full fruit stage, and deciduous stage). The results showed that, compared with that in CK, F1 only significantly decreased Na+ content in the first two growth stages (P<0.05), whereas F2 and F3 significantly decreased Na+ content in the whole growth period (P<0.05), with an average reduction of 33.66% and 57.98%, respectively, and F3 significantly increased soil moisture content (MC), organic matter (OM), alkaline hydrolysis nitrogen (AN), and available phosphorus (AP) contents (P<0.05) during the whole growth period. In the flourishing period of L. barbarum, the Shannon index of F3 increased by 4.41% compared with that of CK. The dominant bacterial phyla in the soil were Proteobacteria, Bacteroidetes, and Actinobacteria, and the dominant bacterial genera were Sphingomonas and Pseudomonas. The most abundant functions of bacterial communities in the study area were chemoheterotrophy and aerobic chemoheterotrophy, with an average relative abundance of 15.07% and 13.16%, respectively. The application of microbial fertilizer increased the chitinolysis function and chloroplast functions of soil bacteria, which F2 increased to the highest degree. Canonical correlation analysis (CCA) showed that MC, Na+, and OM were important factors affecting the composition of the bacterial community. The correlation heat map showed that MC was positively correlated with Planctomycetes (P<0.01), and Gp6 was positively correlated with AN (P<0.01). Compared with that in CK, the F3 treatment increased the relative abundance of Gp6 and optimized the community structure during the growth period. In conclusion, the application of 10500 kg·km-2 microbial fertilizer (F3 treatment) under brackish water irrigation could significantly reduce soil salinity, increase nutrients, and improve the diversity of the soil bacterial community structure, which is conducive to the safe utilization of brackish water and the maintenance of soil ecological health.