[Objective] To studyhydroxyl radical the differentially expressed genes (DEGs) in Halomonas campaniensis XH26 after co-culture with Fe₃O₄ nanoparticles (NPs), and clarify the molecular mechanism of Fe₃O₄ NPs in increasing the ectoine accumulation in strain XH26. [Methods] Strain XH26 was co-cultured with low-, medium-, and high-concentration (0.01, 0.10, and 0.50 g/L respectively in L, M, and H groups) Fe₃O₄ NPs, and the strain cultured without Fe₃O₄ NPs (0 g/L) was taken as the control group (C). Transcriptome sequencing was performed by Illumina HiSeq 300PE. The DEGs between different groups were mined, and key genes were screened for RT-qPCR verification. [Results] Compared with group C, group M showed an increase of 55.67% (708.87 mg/L) in ectoine accumulation, and groups M and H showed increased ferrous ions and antioxidant capacity. The hydroxyl radical content in group H was higher than that in group M. The transcriptomics analysis showed that the DEGs between groups M and C were enriched in arginine/proline metabolism (13), nitrogen metabolism (11), and sulfur metabolism (10) pathways. They were mainly related to the ectoine synthesis pathways (11), electron transport pathways (7), and antioxidant enzyme systems (5). RT-qPCR was employed to verify the expression of lysC, asd, and ectABC involved in ectoine synthesis, astA/B/D/E in arginine metabolic pathway, and argE/H in urea cycle, which showed the results consistent with the results of RNA-seq. [Conclusion] Ectoine is an important stable protective agent for bacterial cells and biomacromolecules. Strain XH26 exposed to the stress of Fe₃O₄ NPs showed increased intracellular reactive oxygen species and altered amino acid/nitrogen metabolism processes. Strain XH26 increased the accumulation of ectoine to cope with the stress of Fe₃O₄ NPs by improving the antioxidant capacity.

Ferroptosis is a novel form of programmed cell death that is iron-dependent and primarily characterized by lipid peroxidation. Studies have indicated that ferroptosis is closely related to the occurrence and development of various diseases. A variety of pathogens have been confirmed to induce ferroptosis of host cells, which facilitates pathogen proliferation and counteracting host immunity. Therefore, ferroptosis extensively participates in the pathophysiological processes caused by pathogen infection. In addition, ferroptosis is involved in the pathological process of many metabolic and poisoning diseases. This paper reviews the research progress in the occurrence and mechanism of ferroptosis in livestock and poultry diseases, aiming to provide reference for further exploring the effect and mechanism of ferroptosis in livestock and poultry diseases.

[Objective] Carbon and nitrogen sources play an important role in providing the energy required for fungal growth and increasing secondary metabolite production. This study aims to investigate the effects of carbon and nitrogen restriction on the growth of Inonotus obliquus and the production of triterpenoid secondary metabolites. [Methods] l-glutamine and d-anhydrous glucose were used as the nitrogen and carbon sources, respectively. A nutrient-sufficient medium (0.877 g/L l-glutamine and 20.000 g/L of d-anhydrous glucose) served as the control group (CK). The experimental groups included a nitrogen-limited medium (N-L) with 0.044 g/L l-glutamine and a carbon-limited medium (C-L) with 2.000 g/L d-anhydrous glucose. In the plate experiment, inoculated plates were incubated at 28 ℃ in a constant temperature incubator, and colony diameters were measured and recorded daily. In the shake flask fermentation experiment, samples were collected on the 5th and 10th days to measure biomass, triterpene content, and the expression levels of triterpene synthesis-related genes. [Results] The plate experiment showed that the C-L group had the fastest mycelium extension, but the mycelium was sparse, and the aging was greatly delayed. The N-L group exhibited faster mycelium extension than the CK group but slower than the C-L group, with the fastest mycelium aging. The shake flask fermentation results showed that the N-L group had the highest biomass. qPCR results demonstrated an upregulation trend in most triterpenoid synthase genes under C-L and N-L conditions. GC-MS analysis revealed that both lanosterol and inotodiol content increased in the C-L and N-L groups compared to the CK group. [Conclusion] Nutritional restriction conditions stimulate the accumulation of triterpenes in I. obliquus.

[Objective] To screen and identify cadmium (Cd)-tolerant bacteria with plant growth-promoting effect from contaminated soil of a mining area in Guangxi, characterize the strain screened out in terms of the Cd tolerance, Cd²⁺ removal efficiency, plant growth-promoting effect, and influence on rice growth under Cd stress, and demonstrate the potential of the strain in plant growth and soil remediation. [Methods] Cd-tolerant bacteria were isolated by the dilution coating method and Cd²⁺ concentration gradient acclimation and further identified based on the morphological, physiological, biochemical characteristics and the 16S rRNA gene phylogenetic tree. The Cd tolerance, Cd²⁺ removal efficiency, and plant growth-promoting effect of the target strain were measured by microdilution, inductively coupled plasma mass spectrometry, and colorimetry. Finally, the effect of the strain on the growth of rice plants under Cd stress was investigated by a pot experiment. [Results] Twelve strains of bacteria with good tolerance to Cd²⁺ were isolated from heavy metal-contaminated soil, and one strain with the best tolerance to Cd was identified as Achromobacter sp. A81, which could grow in the presence of 800 mg/L Cd²⁺. Strain A81 cultured with 10 mg/L Cd²⁺ for 7 days showed the maximum Cd²⁺ removal rate of 44.66%. Both the supernatant and cells of strain A81 demonstrated the ability to adsorb Cd²⁺. Under Cd stress, the strain secreted a large amount of extracellular polymeric substances (EPS) primarily composed of insoluble and soluble proteins. Furthermore, this strain was capable of fixing nitrogen, solubilizing phosphorus, and secreting siderophores, indole-3-acetic acid (IAA), and 1-aminocyclopropane-l-carboxylate (ACC) deaminase, demonstrating remarkable plant growth-promoting effect. Pot experiment results revealed that compared with the group subjected to Cd stress, the rice plants inoculated with strain A81 showed increases of 9.08%, 39.59%, 41.94%, and 73.58% in plant height, root length, stem diameter, and fresh weight, respectively. [Conclusion] This study investigated the Cd tolerance, Cd removal efficiency, and plant growth-promoting effect of Achromobacter sp. A81 and assessed the application potential of this strain in Cd-contaminated soil remediation, providing a scientific basis and high-quality strain resources for the microbial remediation of heavy metal pollution and green agricultural development.

[Objective] We investigated the occurrence of ginger bacterial wilt, identified the pathogens, and screened the antagonistic bacteria, aiming to provide a scientific basis for the control of the disease. [Methods] We systematically investigated the occurrence of bacterial wilt in the main ginger production areas in Chenzhou City, Hunan Province. The ginger tubers with typical symptoms of bacterial wilt and the rhizosphere soil were collected. Major pathogens were isolated and identified based on morphological characteristics and molecular evidence. The pathogenicity of the isolates was determined by inoculation of the isolates to ginger seedlings. Moreover, the sequevars of Ralstonia solanacearum isolates were identified based on the endogenous glucanase gene egl. Finally, the Bacillus strains for biocontrol of the pathogens were screened, and their biocontrol effects were measured. [Results] The average incidence of ginger bacterial wilt in the field was 8.52%. Two bacterial strains FJAT-15492 and FJAT-15494 were isolated from diseased ginger tubers, and three bacterial strains FJAT-15495, FJAT-15496, and FJAT-15497 were isolated from the rhizosphere soil of diseased ginger. The strain FJAT-15492 was identified as Enterobacter mori and the other four isolates were R. solanacearum. Both the isolates of E. mori and R. solanacearum could infect ginger seedlings and cause bacterial wilt. R. solanacearum strains existed in both diseased ginger tubers and rhizosphere soil, while E. mori only existed in diseased ginger tubers, with the count (1.33×10³ CFU/g) lower than that (5.67×10³ CFU/g) of R. solanacearum.Furthermore, the R. Solanacearum isolates were identified as phylotype Ⅰ and sequevar 14. Brevibacillus brevis FJAT-JK-2 demonstrated inhibitory effect on R. solanacearum, and Bacillus velezensis FJAT-54560 on E. mori, with inhibition zone diameters of 19.41 mm and 16.11 mm and indoor control effects of 69.45% and 61.11%, respectively. Moreover, the fermentation mixture of the two biocontrol strains had the field control effect of 52.57%. [Conclusion] This work identified the pathogens of ginger bacterial wilt and provided two new biocontrol strains against the disease.

[Objective] Preliminary studies have identified four protein elicitors from the whole genome of Saccharothrix yanglingensis Hhs.015 that can induce a hypersensitive response (HR) in Nicotiana benthamiana. This study investigated the two elicitors capable of triggering a strong HR and their associated immune mechanisms, aiming to provide a basis for probing into the molecular mechanisms by which Hhs.015 enhances the disease resistance of plants. [Methods] The protein elicitors capable of inducing the immune responses of plants were screened based on the HR and reactive oxygen species (ROS) levels. A prokaryotic expression system was used to purify the proteins. Furthermore, we verified the roles of the protein elicitors in inducing plant disease resistance by observing the disease spots, measuring the activities of defense-related enzymes, and analyzing the expression of defense genes. Additionally, we treated Arabidopsis thaliana seedlings with the protein elicitors to evaluate the plant growth-promoting effects of the elicitors. [Results] The protein elicitors HSyp1 and HSyp2 from Hhs.015 that could induce a HR, callose and ROS deposition, and upregulation of defense genes in N. benthamiana, were screened and found to be soluble. HSyp1 and HSyp2 enhanced the resistance of different plants to Sclerotinia sclerotiorum, Phytophthora capsica, and Valsa mali. Furthermore, HSyp1 and HSyp2 promoted the cotyledon and root development of A. thaliana seedlings, and HSyp2 exhibited stronger plant growth-promoting effect than HSyp1. [Conclusion] This study identified two protein elicitors HSyp1 and HSyp2 capable of triggering immune responses, enhance disease resistance, and promoting growth of plants. The findings provide a theoretical basis for the development of new biocontrol agents and offer experimental evidence for their future field application.

[Objective] This study investigated the optimal proportion of green manure replacing chemical fertilizer and its effect on soil fungal community in the paddy field of Ultisol, aiming to achieve soil fertilization and sustainable utilization of Ultisol in southern China. [Methods] This study set seven treatments: no fertilizer (Control), application of Chinese milk vetch without chemical fertilizer in early season rice (G), conventional application of chemical fertilizer in early season rice (NPK100), application of Chinese milk vetch and conventional chemical fertilizer in early season rice (NPK100+G), application of Chinese milk vetch and 80% conventional chemical fertilizer in early season rice (NPK80+G), application of Chinese milk vetch and 60% conventional chemical fertilizer in early season rice (NPK60+G), and application of Chinese milk vetch and 40% conventional chemical fertilizer in early season rice (NPK40+G). The conventional chemical fertilizer was applied in late season rice for other treatments except the Control. The root surface soil samples of different treatments were collected at the maturity stage of late rice for the measurement of soil properties. At the same time, high-throughput sequencing (Illumina MiSeq) was employed to analyze the features of soil fungal community. [Results] Compared with NPK100, the treatments of green manure replacing chemical fertilizer increased the yields of rice and straw. Different treatments significantly altered the soil fungal community composition (P=0.001). Replacing medium and low amounts of chemical fertilizer with green manure increased the relative abundance of saprophytic fungi in soil, which increased the conversion rate of soil organic matter and nutrient turnover rate. Compared with NPK100, replacing 0, 20%, and 40% chemical fertilizer with green manure increased the relative abundance of saprophytic fungi in soil by 33.55%, 167.27%, and 55.28%, respectively. In addition, replacing medium and low amounts of chemical fertilizer with green manure decreased the relative abundance and diversity of potential plant pathogens in soil. [Conclusion] Replacing medium and low amounts (20%–40%) of chemical fertilizer with green manure not only increased rice yield but also reduced environmental pollution, improved soil nutrients, and optimized the fungal community in soil. This study systematically evaluated the effect of replacing different proportions of chemical fertilizer with green manure on the Ultisol paddy ecosystems. The results provided a theoretical basis for the sustainable development of agriculture in the Ultisol region of southern China.

[Objective] Epoxide hydrolases (EHs) play a key role in the synthesis of chiral pharmaceuticals. We explored new EHs by engineering or gene retrieval, aiming to enrich and discover more high-performance EHs. [Methods] A novel epoxide hydrolase (Aspergillus carlsbadensis epoxide hydrolase, AcEH) from Aspergillus carlsbadensis was identified by gene retrieval technology. We then used AutoDock2 to predict the key hydrolysis sites of AcEH and employed computational design to clarify the influences of important sites on the structure and catalytic mechanism of AcEH. [Results] The primary structure of the novel EH had three characteristic α/β EH motifs: HGWP, GYTFS, and GGDIGS. AcEH exhibited high activity and could completely hydrolyze styrene oxide (SO) within 15 min, with a specific activity of 13 951 U/g. The K_m, V_max, and k_cat/K_m of AcEH were (107.07±57.98) mmol/L, (37.22±17.85) μmol/(min·mg), and 1.17 mmol/(L·s), respectively. The key hydrolysis sites of AcEH were Asp192-His372-Glu346, which catalyzed the triad, and two conserved tyrosine residues, Tyr251/314. The mutations R49L and R49Y caused enzyme inactivation, while the mutation Y45L resulted in the formation of inactive inclusion bodies. The interaction network revealed that changes in the 49th amino acid residue disrupted the interactions between key active site residues, leading to enzyme inactivation. On the other hand, the alteration of the 45th amino acid residue destabilized the enzyme structure, leading to the formation of inclusion bodies. [Conclusion] This study discovered a novel EH and analyzed its hydrolysis mechanism. The findings provide valuable insights for further research and engineering on this enzyme.

[Objective] To explore the differences and potential associations of endophytic microbial communities in different niches of chili pepper and provide a theoretical basis for the exploration and application of endophytic microbial resources in chili pepper. [Methods] The 16S rRNA and internal transcribed spacer (ITS) genes sequencing were employed to study the community structure characteristics of endophytic bacteria and fungi in different ecological niches (roots, stems, leaves, and fruits) of 91 pepper germplasm accessions, along with functional annotations. Additionally, co-occurrence network analysis and traceability analysis were performed on the endophytic bacterial communities. [Results] The operational taxonomic unit (OTU) of endophytic microbial communities were highly common among the four ecological niches, including 46.36% common bacterial OTUs and 29.66% common fungal OTUs. The diversity of endophytic bacterial and fungal communities in chili pepper exhibited variations across different ecological niches, with the endophytic communities in roots being distinctly separated from those in the other three niches (P<0.05). The Shannon index of endophytic bacteria varied significantly among niches, whereas that of endophytic fungi remained relatively stable. The dominant endophytic bacteria in chili pepper were Proteobacteria, Firmicutes, and Bacteroidota, with Proteobacteria being enriched in the roots and Firmicutes and Bacteroidetes being predominant in the fruits. Ascomycota and Basidiomycota, the dominant endophytic fungal phyla, exhibited minimal differences in relative abundance across the four ecological niches. Functional annotation results indicated that chili pepper harbored various endophytic bacteria capable of synthesizing secondary metabolites and antibiotics. Within the fungal community, pathogenic fungi were found to have the highest relative abundance. Additionally, more than 80.0% of the endophytic bacteria in chili pepper originated from their directly associated morphologically lower niches, exhibiting complex interaction networks, strong community stability, and a modular structure. [Conclusion] Compared with the endophytic fungal community, the endophytic bacterial community in chili pepper is sensitive to changes in ecological niches, while the niche specificity of the fungi is comparatively weak. The endophytic bacteria associated with each niche of chili pepper primarily originate from the niche located beneath, exhibiting significant niche enrichment, where the roots serving as a crucial source in shaping the endophytic bacterial community.

Truffles must be symbiotic with plants to form ectomycorrhiza (ECM), which facilitates the formation of fruiting bodies by mutually beneficial exchanges of substances. [Objective] To elucidate the flow of substances between Tuber sinense and Pinus yunnanensis in a symbiosis relationship. [Methods] Liquid chromatography-mass spectrometry (LC-MS) was employed to analyze the metabolite profiles of freshly harvested T. sinense (SL) and P. yunnanensis roots (SG). [Results] In SL and SG, 1 304 and 1 516 substances were detected respectively, including 399 SL-specific substances (SLSs) and 611 SG-specific substances (SGSs). There were 294 common differential substances, including 93 up-regulated substances (DEMs-up) and 201 down-regulated substances in SL. The network correlation analysis revealed that 92 of the 100 substances with the relative content ≥2.0 (40 SLSs and SGSs and 60 DEMs-up) displayed significant correlations. Twenty-nine associated substances in SLSs and SGSs and 19 substances in DEMs-up were enriched in 15 important pathways, which mainly involved secondary metabolite biosynthesis, amino acid biosynthesis and metabolism, and vitamin biosynthesis and metabolism. [Conclusion] A network correlation existed between T. sinense and P. yunnanensis pine roots metabolites. Some substances in truffles and pine roots, including adenosine 3′, 5′-cyclic monophosphate (cAMP), phytosterol, and indole-3-acetic acid, had regulatory effects on the development of fruiting bodies. The findings provided a theoretical basis for further studying the potential signaling molecules associated with fruiting body development and elucidating the symbiotic mechanism between T. sinense and pines. Additionally, this study laid a practical basis for screening the substances promoting the growth of mycorrhizal seedlings and fruiting bodies and for large-scale artificial cultivation of truffles.