Influence of Bacillus subtilis strain Z-14 on microbial ecology of cucumber rhizospheric vermiculite infested with fusarium oxysporum f. sp. cucumerinum.

Fusarium oxysporum (FO) is a typical soil-borne pathogenic fungus, and the cucumber wilt disease caused by F. oxysporum f. sp. cucumerinum (FOC) seriously affects crop yield and quality. Vermiculite is increasingly being used as a culture substrate; nevertheless, studies exploring the effectiveness and mechanisms of biocontrol bacteria in this substrate are limited. In this study, vermiculite was used as a culture substrate to investigate the control effect of Bacillus subtilis strain Z-14 on cucumber wilt and the rhizospheric microecology, focusing on colonization ability, soil microbial diversity, and rhizosphere metabolome. Pot experiments showed that Z-14 effectively colonized the cucumber roots, achieving a controlled efficacy of 61.32% for wilt disease. It significantly increased the abundance of Bacillus and the expression of NRPS and PKS genes, while reducing the abundance of FO in the rhizosphere. Microbial diversity sequencing showed that Z-14 reduced the richness and diversity of the rhizosphere bacterial community, increased the richness and diversity of the fungal community, and alleviated the effect of FO on the community structure of the cucumber rhizosphere. The metabolomics analysis revealed that Z-14 affected ABC transporters, amino acid synthesis, and the biosynthesis of plant secondary metabolites. Additionally, Z-14 increased the contents of phenylacetic acid, capsidol, and quinolinic acid, all of which were related to the antagonistic activity in the rhizosphere. Z-14 exhibited a significant control effect on cucumber wilt and influenced the microflora and metabolites in rhizospheric vermiculite, providing a theoretical basis for further understanding the control effect and mechanism of cucumber wilt in different culture substrates.

Analysis of key genes for the survival of Pantoea agglomerans under nutritional stress.

The absolute amount of nutrients on plant leaves is usually low, and the growth of epiphytic bacteria is typically limited by nutrient content. Thus, is of great significance to study the survival mechanism of epiphytes under nutritional stress for plant disease control. In this paper, Pantoea agglomerans CHTF15 isolated from walnut leaves was used to detect the key genes for the survival of the bacterium under simulated nutrient stress in artificial medium. Genome sequencing was combined with transposon insertion sequencing (Tn-seq) for the detection technique. A total of 105 essential genes were screened from the whole genome. The genes were mainly related to the nucleotide metabolism, protein metabolism, biological oxidation and the gene repair of bacteria analyzed by gene ontology (GO) enrichment analysis. Volcano map analysis demonstrated that the functions of the 15 genes with the most significant differences were generally related to the synthesis of amino acids or proteins, the nucleotide metabolism and homologous recombination and repair. Competitive index analysis revealed that the deletion of the genes dksA and epmA regulating protein synthesis, the gene ribB involved in the nucleotide metabolism and the gene xerD involved in recombination repair induced a significant reduction in the survival ability of the corresponding mutants in the 0.10 % YEP medium and the walnut leaf surface. The results act as a foundation for further in-depth research on the infection process and the mechanisms of pathogenic bacteria.

Therapeutic potential of the chemical composition of Dendrobium nobile Lindl.

Dendrobium nobile Lindl. belongs to the genus Dendrobium of the orchid family and is a valuable herbal medicinal material. The information in this paper has been collected from the scientific literature databases including PubMed, Google Scholar, Web of Science, SciFinder, China National Knowledge Infrastructure, published books, Ph.D., and M.S. dissertations systematically in recent 20 years. "Dendrobium nobile Lindl.," "chemical composition," "pharmacological activities," and "diseases" were used as search terms to screen the literature. The collected chemical compositions are classified and summarized according to their different chemical structures, and the clinical disease treatment effects of Dendrobium nobile Lindl. are classified and summarized based on their pharmacological activities and different experimental disease models. Recent studies have revealed that Dendrobium nobile Lindl. contains chemical components such as alkaloids, bibenzyls, sesquiterpenes, phenanthrenes, and polysaccharides, and that its pharmacological activities are closely related to the chemical components, with pharmacological activities such as anti-tumor, anti-aging, immune enhancement, hypoglycemic, and anti-cataract. Currently, researchers are conducting extensive and detailed studies on Dendrobium nobile Lindl. and research experiments on its chemical constituents in the treatment of various clinical diseases. Therefore, the purpose of this paper is to review the chemical composition of Dendrobium nobile Lindl. and its experimental studies in the treatment of diseases and to provide a scientific reference for the future application of Dendrobium nobile Lindl. in the treatment of diseases.

Actively tunable rasorber with broadband RCS reduction and low infrared emissivity.

In this paper, an actively tunable rasorber with broadband RCS reduction and low infrared emissivity is proposed. The rasorber can achieve flexible control of the peak of the transmission frequency and make the platform invisible in multiple spectrum. Based on the combination of varactor diodes and bandpass frequency-selective surface (FSS), the transmission window can be continuously tuned from 1.8 to 4.5 GHz. The designed rasorber has more than 10 dB RCS reduction from 5.4 to 14.1 GHz. Furthermore, an infrared low emissivity layer based on ITO resistance film is added above the rasorber, and the average infrared emissivity of the measured surface is 0.33. The experimental and simulation results are in good agreement. This work is expected to be applied to frequency hopping secure communication and ultra-wideband, multi-spectrum stealth.

Complete Genome Sequence of Pantoea agglomerans CHTF15, a Walnut Pathogen.

The phytopathogen Pantoea agglomerans belongs to the Bacteria, Proteobacteria, Gammaproteobacteria, Enterobacterales, Erwiniaceae in species classification. It causes disease symptoms in many plants such as corn, banana, and walnut. This study aimed to report the complete genome of P. agglomerans CHTF15, which represents the first whole-genome sequence of an isolate from diseased walnut leaves. The total length of the assembled genome was 4,820,607 bp, with an average GC content of 55.3%, including a circular chromosome and three circular plasmids, two of which were previously unreported sequences and one was announced previously. The CHTF15 genome helps understand the pathogenic mechanism of this important plant pathogen and provides an important theoretical basis for disease epidemic and field control. [Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 "No Rights Reserved" license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2023.

Metabolomic and Transcriptome Analysis of the Inhibitory Effects of Bacillus subtilis Strain Z-14 against Fusarium oxysporum Causing Vascular Wilt Diseases in Cucumber.

Controlling cucumber Fusarium wilt caused by Fusarium oxysporum f. sp. cucumerinum (FOC) with Bacillus strains is a hot research topic. However, the molecular mechanism of Bacillus underlying the biocontrol of cucumber wilt is rarely reported. In this study, B. subtilis strain Z-14 showed significant antagonistic activity against FOC, and the control effect reached 88.46% via pot experiment. Microscopic observations showed that strain Z-14 induced the expansion and breakage of FOC hyphae. The cell wall thickness was uneven, and the organelle structure was degraded. The combined analysis of metabolome and transcriptome showed that strain Z-14 inhibited the FOC infection by inhibiting the synthesis of cell wall and cell membrane, energy metabolism, and amino acid synthesis of FOC mycelium, inhibiting the clearance of reactive oxygen species (ROS) and the secretion of cell wall-degrading enzymes (CWDEs), thereby affecting mitogen-activated protein kinase (MAPK) signal transduction and inhibiting the transport function.

The pathophysiological mechanisms underlying diabetic retinopathy.

Diabetic retinopathy (DR) is the most common complication of diabetes mellitus (DM), which can lead to visual impairment and even blindness in severe cases. DR is generally considered to be a microvascular disease but its pathogenesis is still unclear. A large body of evidence shows that the development of DR is not determined by a single factor but rather by multiple related mechanisms that lead to different degrees of retinal damage in DR patients. Therefore, this article briefly reviews the pathophysiological changes in DR, and discusses the occurrence and development of DR resulting from different factors such as oxidative stress, inflammation, neovascularization, neurodegeneration, the neurovascular unit, and gut microbiota, to provide a theoretical reference for the development of new DR treatment strategies.