Search

The electronic and optical properties of hydrogenated silicene at different torsion angles are investigated using the density functional theory (DFT). It was found that when silicene was hydrogenated, the Si atoms were pulled out of plane due to covalent interactions between the Si and H atoms, increasing their flexural height to 0.731 Å. Torsional deformation decreases the structural stability of hydrogenated silicene and its adsorption energy decreases with increasing twist angle. Under the effect of torsion deformation, the bandgap of hydrogenated silicene increases and then decreases. The bandgap is 2.168 eV at a torsion angle of 0∘, indicating a wide bandgap semiconductor. Mulliken's charge population analysis shows that charge transfer occurs between Si–H atoms, with Si atoms losing electrons and becoming positively charged and H atoms gaining electrons and becoming negatively charged. From the analysis of optical properties, the torsional deformation induced the maximum absorption and reflection peaks of all the hydrogenated silicene systems to appear in the ultraviolet region. Compared with the system without torsional deformation, these peaks exhibit varying degrees of red and blue shifts. The above findings provide guidance for the application of silicene in nanooptoelectronic devices. [ABSTRACT FROM AUTHOR]

The effect of biaxial strain on O-doped monolayers MoS2 has been systematically studied by the first-principles calculations. It is shown that the strain decreases the structural stability of O-doped monolayer MoS2. Between 0% and 12% tensile strains, the bandgap steadily narrows. At different compression strains, the bandgap increases and then decreases. The optical properties analysis shows that the strain causes the peaks of both the real and imaginary parts of the dielectric function to appear in the low energy region. And it affects the absorption and reflection peaks of the doping system so that it has a strong absorption of photons in the ultraviolet region. The doping system shows resonance in the range of 0–10 eV. The results of this study verify that strain can properly regulate the electronic and optical properties of O-doped monolayer MoS2, and provide a theoretical reference for the implementation of MoS2 in optoelectronic devices. [ABSTRACT FROM AUTHOR]

• Shear deformation reduces the structural stability of the doped system. The forbidden band width of the doped system decreases sequentially with increasing shear deformation, while conductivity increases. • The density of states of both intrinsic and doped systems is primarily contributed by the 4d and 3p orbitals of the Mo and S atoms, respectively. • Analysis of the optical properties reveals that shear deformation enhances the static permittivity of the doped systems, leading to an increased ability to bind charges. • Compared to the doped system without shear deformation, absorption peaks of the remaining doped systems shift towards the high energy region, resulting in enhanced utilization of ultraviolet light. The effect of O-atom doping on the electronic and optical properties of monolayer MoS 2 under shear deformation has been systematically investigated using first principles. The results show that shear deformation reduces the structural stability of the doped system. The forbidden band width of the doped system decreases sequentially with increasing shear deformation, while conductivity increases. The density of states of both intrinsic and doped systems is primarily contributed by the 4d and 3p orbitals of the Mo and S atoms, respectively. Analysis of the optical properties reveals that shear deformation enhances the static permittivity of the doped systems, leading to an increased ability to bind charges. Additionally, absorption and reflection peaks of all doped systems occur in the ultraviolet region. Compared to the doped system without shear deformation, absorption peaks of the remaining doped systems shift towards the high energy region, resulting in enhanced utilization of ultraviolet light. In the energy range of 16.7–17.3 eV, peak energy loss of all doped systems decreases sequentially, suggesting that shear deformation can reduce energy loss. These results demonstrate that shear deformation can modulate the optoelectronic properties of O-doped monolayer MoS 2 and provide a theoretical foundation for practical applications in semiconductor devices. Variation of band gap values of intrinsic and O-doped monolayer MoS 2 under different shear deformation [Display omitted] [ABSTRACT FROM AUTHOR]

In the present paper, the effect of different bent angles on structural stability, electronic structure, and optical properties of Na absorbed borophene system is investigated using the density functional theory. The structure of the borophene was almost unchanged and the planar structure was not disrupted after the adsorption of a Na atom. Directly above the bottom B–B bonds is considered as the optimal adsorption position of single. The stability of the Na adsorbed borophene system can be decreased under the condition of different bent angles. The adsorption of Na atoms changes the energy band structure of the intrinsic borophene according to the calculation results of energy band structure and density of states, which resulting the conduction band contains more impurities. The 2p orbital of Na and the 3p orbital of B hybridize between −4 eV and 6 eV. Bending deformation gives rise to the electron transfer between Na atoms and B atoms. In terms of optical properties, the bending deformation improves the absorption of infrared light and the catalytic activity of light in the adsorbed system. • The structure of the borophene was almost unchanged and the planar structure was not disrupted after the adsorption of a Na atom. • The stability of the Na adsorbed borophene system can be decreased under the condition of different bent angles. • The adsorption of Na atoms changes the energy band structure of the intrinsic borophene so that its conduction band contains more impurities. • The bending deformation improves the absorption of infrared light and the catalytic activity of light in the adsorbed system. [ABSTRACT FROM AUTHOR]

A first-principles method was used to explore the influence of tensile strain on the electrical and optical characteristics of Nb-doped MoSe2. The tensile strain has been discovered to have a higher influence on the electrical structure of the Nb-doped MoSe2 system than pure monolayer MoSe2. According to the energy band structure study, the pure monolayer MoSe2 is a direct bandgap semiconductor, but the system doped with Nb instead of Mo atoms is a p-type-doped semiconductor. The bandgap of the Nb-doped MoSe2 system decreases gradually with the increase of tensile strain, but still maintains the p-type semiconductor properties, and the bandgap of the pure monolayer MoSe2 also decreases gradually with the increase of tensile strain. From the density of states analysis, it is found that for the total density of states of the doped system at different tensile strains, it is mainly contributed by the Mo-4d and Se-4p orbitals. The optical properties analysis showed that the doped system under tensile strain had higher absorption coefficient and reflectance peak than the Nb-doped MoSe2 system without tensile strain. Additionally, the doped system showed redshift phenomenon in both the absorption and reflection peaks as the tensile strain increased. [ABSTRACT FROM AUTHOR]

The influence of shear deformation on the electronic and optical properties of the Al-doped arsenene has been investigated using the first-nature principle based on density general function theory. Within this study, the 5.882% doping concentration in the Al-doped arsenene makes it reasonably stable and the doping of Al atoms causes the arsenene to exhibit quasi-metallic properties. The combined energy calculations show that the structural stability of the Al-doped arsenene is not significantly affected by shear deformation. With increased shear deformation, the band gap of intrinsic arsenene reduces, and the band gap of the Al-doped arsenene similarly does. Optical properties analysis indicates that shear deformation redshifts both the absorption and reflection peaks of the doped system. [ABSTRACT FROM AUTHOR]

The effect of biaxial tensile deformation on the optoelectronic properties of Al-doped monolayers SnS2 is explored using density functional theory. We found that the pure SnS2 monolayer is an indirect bandgap semiconductor, and with Al doping it changes to a p-type semiconductor with a lowered bandgap value. After applying biaxial tensile deformation to the doped system, i.e., with the increase of tensile strain, bandgap value decreases. Analyzing the density of states, it is found that the conduction band in a doped system is primarily made of the Sn-5s orbital and the S-3p orbital, and the valence band is primarily made of Sn-5p orbital and S-3p orbital, with the majority of S-3p orbital. The conduction and valence bands change with the rise in tensile strain, and hence the gap in the density of states close to the Fermi energy level shrinks. It is also noticed that the absorption coefficient peaks and reflection peaks of the SnS2 doped system subjected to biaxial tensile strain are blueshifted. The absorption coefficient and reflectance peaks of the doped system show a tendency to increase and then decrease with the increase of tensile strain. [ABSTRACT FROM AUTHOR]

First-principles research has been used to carefully examine the structural stability of the architecture, electronic structure, and optical characteristics of monolayer WS2-doped Mo atoms during shear deformation. Calculations show that the required formation energy gradually increases when shear deformation is increased from 2% to 8%, the bandgap of the system decreases from 1.732eV to 0.922eV, and the static dielectric function increases from 2.59 to 2.74. The absorption peaks are maximum for all doped systems between 11.5eV and 12.5eV. The peak absorption of the deformed system is redshifted compared to the original doped system. With increasing shear deformation, the peak energy loss of the system shows a decrease followed by an increase. [ABSTRACT FROM AUTHOR]

Context: In this paper, the electronic and optical properties of Cr-doped monolayer MoS2 under uniaxial tensile strain are investigated by first-principle calculations. It is shown that uniaxial tensile strain can significantly change the electronic and optical properties of Cr-doped monolayer MoS2, and the bandgap value of the intrinsic MoS2 system gradually decreases with the increase of tensile strain, while the bandgap value of the Cr-doped MoS2 system is relatively stable. However, when the stretching reaches a certain degree, both the intrinsic and doped systems become metallic. From the analysis of the density of states, it is found that new electronic states and energy levels appear in the intrinsic MoS2 system and all Cr-doped monolayer MoS2 systems with the increase of the tensile strain, but the changes in the density of states diagrams of the Cr-doped monolayer MoS2 system are relatively small, which is mainly attributed to the effect of the Cr-doped atoms. The analysis of optical properties displays that the stretched doped system differs from the intrinsic MoS2 system in terms of dielectric function, absorption and reflection, energy loss function, and refractive index. Our results suggest that uniaxial tensile strain can be used as an effective means to modulate the electronic structure and optical properties of Cr-doped monolayer MoS2. These findings provide a theoretical basis for understanding the optoelectronic properties of MoS2 and its doped systems as well as their applications in optoelectronic devices. Methods: Based on the first principle of density functional theory framework and the CASTEP module in Materials Studio software (Perdew et al. in Phys Rev Lett 77(18):3865–3868, 1996). The structure of Cr atom-doped MoS2 systems and MoS2 systems were optimized using the generalized gradient approximation plane-wave pseudopotential method (GGA) and Perdew-Burke-Ernzerhof (PBE) generalized functions under 3%, 6%, and 9% tensile deformation, and the corresponding formation energy, bond length, electronic structure, and optical properties of the models were analyzed. The Grimme (J Comput Chem 27(15):1787–1799, 2006) vdW correction with 400 eV cutoff was used in Perdew-Burke-Ernzerhof (PBE) functional to optimize the geometry until the forces and energy converged to 0.02 eV/Å and 1.0e-5eV/atom, respectively. For each model structure optimization, the K-point grid was assumed to be 4×4×1, using the Monkhorst-Pack special K-point sampling method. After the MoS2 supercell convergence test, the plane-wave truncation energy was chosen to be 400 eV. Following geometric optimization, the iterative accuracy converged to no less than 1.0×10−5 eV/atom for total atomic energy and less than 0.02 eV/Å for all atomic forces. We created a vacuum layer of 18 Å along the Z-axis to prevent the impact of periodic boundary conditions and weak van der Waals forces between layers on the monolayer MoS2. In this paper, a total of 27 atoms were used for the 3×3×1 supercell MoS2 system, which consists of 18 S atoms and 9 Mo atoms. [ABSTRACT FROM AUTHOR]

The effects of tensile and compressive deformation on the structural stability, electronic structure and optical properties of the Zn atom-adsorbed borophene system, which are exhibited by reflectivity, absorption coefficient, bandgap and adsorption energy, were studied using the first-principles calculations based on density functional theory (DFT). The borophene planes were found to be distorted following Zn atom adsorption. The adsorption energy calculations show that the stability decreases both under tensile and compressive strains. When tensile and compressive loading increase to 5%, respectively, the system loses the stability and the ability of adsorbing Zn atoms on borophene. The band structure and density of states analysis show that the band structure of borophene is changed by the Zn atom adsorption, with a band overlap near the Fermi level and more impurity energy levels in the conduction band. The hybridization is formed between Zn atom and borophene in the range of –12eV to 6eV, with the s and p orbitals both contributing to the conduction and valence bands, but p orbitals make a larger contribution to the total density of states than s orbitals. Studies of optical properties have shown that tensile and compressive strains both increase the dielectric constant of the adsorbed system, with compressive strains causing a redshift in the major peaks of the real and imaginary parts of the spectrum. The tensile strain has little effect on the absorption coefficient and reflectance of the borophene. As the compressive strain increases, the peak absorption coefficient of the adsorbed system is shifted to the blue and the peak reflectance is redshifted. [ABSTRACT FROM AUTHOR]

Bacillus subtilis B3 was found to produce lipopeptides iturins and fengycin that have activity against several plant pathogens such as Fusarium graminearum, Rhizoctonia solani, Rhizoctonia cerealis, and Pyricularia grisea. A 3642-bp genomic region of B. subtilis B3 comprising srfDB3, aspB3, lpaB3, and yczEB3 genes that resulted in biosynthesis of surfactin in B. subtilis 168 was cloned, sequenced, and characterized. Among them, the srfDB3 gene encodes thioesterase, which is required for biosynthesis of surfactin in B. subtilis; the aspB3 gene encodes a putative aspartate aminotransferase-like protein; the lpaB3 encodes phosphopantetheinyl transferase, which shows high identity to the product of lpa-14 gene regulating the biosynthesis of iturin A and surfactin in B. subtilis RB14; the yczEB3 encodes a YczE-like protein with significant similarities in signal peptide and part of the ABC transport system. The genetic regions between the srfD gene and lpa gene from B. subtilis B3 and B. subtilis A13, which produces iturin A, contain an approximate 1-kb nucleotide fragment encoding an aspartate aminotransferase-like protein; however, the relevant regions from B. subtilis 168 and B. subtilis ATCC21332 producing surfactin comprise an approximately 4-kb nucleotide fragment encoding four unknown proteins. There is 73% identity between the Lpa family and the Sfp family, although both are highly conserved. [ABSTRACT FROM AUTHOR]

Summary: The plant rapid alkalinization factor (RALF) peptides function as key regulators in cell growth and immune responses through the receptor kinase FERONIA (FER). In this study, we report that the transcription factor FgPacC binds directly to the promoter of FgRALF gene, which encodes a functional homologue of the plant RALF peptides from the wheat head blight fungus Fusarium graminearum (FgRALF). More importantly, FgPacC promotes fungal infection via host immune suppression by activating the expression of FgRALF. The FgRALF peptide also exhibited typical activities of plant RALF functions, such as inducing plant alkalinization and inhibiting cell growth, including wheat (Triticum aestivum), tomato (Solanum lycopersicum) and Arabidopsis thaliana. We further identified the wheat receptor kinase FERONIA (TaFER), which is capable of restoring the defects of the A. thaliana FER mutant. In addition, we found that FgRALF peptide binds to the extracellular malectin‐like domain (ECD) of TaFER (TaFERECD) to suppress the PAMP‐triggered immunity (PTI) and cell growth. Overexpression of TaFERECD in A. thaliana confers plant resistance to F. graminearum and protects from FgRALF‐induced cell growth inhibition. Collectively, our results demonstrate that the fungal pathogen‐secreted RALF mimic suppresses host immunity and inhibits cell growth via plant FER receptor. This establishes a novel pathway for the development of disease‐resistant crops in the future without compromising their yield potential. [ABSTRACT FROM AUTHOR]

With the development of industrialization, the use of mercury in industry has become more and more widespread, causing serious impacts on the environment. It is therefore urgent to find new effective ways to combat mercury pollution. In this paper, The effect of C, O, P, Ni and Au doping on the adsorption of Hg atoms by WS 2 has been investigated based on the first nature principle of density functional theory. The electronic structures and optical properties of the adsorbed systems were calculated after atomic doping. The results show that the absolute value of the adsorption energy of the intrinsic adsorption system is small and does not favour the adsorption of Hg on WS 2. However, after C, P, Ni and Au doping, the adsorption energy of the system is significantly increased and a strong charge transfer between WS 2 and Hg atoms occurs, as well as a significant change in the band gap of the structure. This suggests that atomic doping favors the adsorption of Hg by WS 2. The effect of O doping on the adsorption system is not significant. In addition, a study of the optical properties revealed that the static dielectric constants of the system appeared to increase to varying degrees after the doping of the atoms. The doping of P, Ni and Au atoms increases the light absorption coefficient and contributes to the photocatalytic efficiency of the structures. The doped atoms cause a red shift in the reflectivity peak of the adsorbed system. In summary, the doping of C, P, Ni and Au enhances the adsorption of Hg atoms on WS 2. O doping has less effect on the adsorption of Hg on WS 2. • In this paper, the effect of C, O, P, Ni and Au doping on the adsorption of Hg atoms by WS2 was investigated. • The results show that atomic doping favors the adsorption of Hg by WS2. • Atomic doping alters the electronic properties of the structure. • Atomic doping alters the optical properties of the structure. [ABSTRACT FROM AUTHOR]

In this paper, we study the effects of different doping concentrations of O, Se, and Te atoms on the electronic structure and optical properties of single layer WS2 based on the density generalization theory of the first principles. The most stable structure. The system doped with Te atoms shows a shift from direct to indirect band gap, and the band gap of the system doped with Se atoms increases slightly. When investigating the optical properties, we also found that the absorption of light in each doped system mostly occurs in the ultraviolet region, and the absorption of light in the system doped with O atoms decreases, while the absorption of light in the system doped with Se and Te atoms changes with different frequencies. The reflectivity is higher than the intrinsic state. [ABSTRACT FROM AUTHOR]

The type VI secretion system (T6SS) of many gram‐negative bacteria injects toxic effectors into adjacent cells to manipulate host cells during pathogenesis or to kill competing bacteria. However, the identification and function of the T6SS effectors remains only partly known. Pantoea ananatis, a gram‐negative bacterium, is commonly found in various plants and natural environments, including water and soil. In the current study, genomic analysis of P. ananatis DZ‐12 causing brown stalk rot on maize demonstrated that it carries three T6SS gene clusters, namely, T6SS‐1, T6SS‐2, and T6SS‐3. Interestingly, only T6SS‐1 secretion systems are involved in pathogenicity and bacterial competition. The study also investigated the T6SS‐1 system in detail and identified an unknown T6SS‐1‐secreted effector TseG by using the upstream T6SS effector chaperone TecG containing a conserved domain of DUF2169. TseG can directly interact with the chaperone TecG for delivery and with a downstream immunity protein TsiG for protection from its toxicity. TseG, highly conserved in the Pantoea genus, is involved in virulence in maize, potato, and onion. Additionally, P. ananatis uses TseG to target Escherichia coli, gaining a competitive advantage. This study provides the first report on the T6SS‐1‐secreted effector from P. ananatis, thereby enriching our understanding of the various types and functions of type VI effector proteins. [ABSTRACT FROM AUTHOR]

The gram‐positive bacterium Bacillus velezensis strain DMW1 produces a high level of antimicrobial metabolites that can suppress the growth of phytopathogens. We investigated the mechanism used by degQ and the degS/degU two‐component system to regulate the biocontrol characteristics of DMW1. When degQ and degU were deleted, the biofilm formation, cell motility, colonization activities, and antifungal abilities of ΔdegQ and ΔdegU were significantly reduced compared to wild‐type DMW1. The expression levels of biofilm‐related genes (epsA, epsB, epsC, and tasA) and swarming‐related genes (swrA and swrB) were all down‐regulated. We also evaluated the impact on secondary metabolites of these two genes. The degQ and degU genes reduced surfactin and macrolactin production and up‐regulated the production of fengycin, iturin, bacillaene, and difficidin metabolites. The reverse transcription‐quantitative PCR results were consistent with these observations. Electrophoretic mobility shift assay and microscale thermophoresis revealed that DegU can bind to the promoter regions of these six antimicrobial metabolite genes and regulate their synthesis. In conclusion, we provided systematic evidence to demonstrate that the degQ and degU genes are important regulators of multicellular behaviour and antimicrobial metabolic processes in B. velezensis DMW1 and suggested novel amenable strains to be used for the industrial production of antimicrobial metabolites. [ABSTRACT FROM AUTHOR]

Plants cannot avoid environmental challenges and are constantly threatened by diverse biotic and abiotic stresses. However, plants have developed a unique immune system to defend themselves against the invasion of various pathogens. Melatonin, N‐acetyl‐5‐methoxytryptamine has positive physiological effects in plants that are involved in disease resistance. The processes underlying melatonin‐induced pathogen resistance in plants are still unknown. The current study explores how melatonin regulates the plant‐disease interaction in maize. The results showed that 400 μM melatonin strongly reduced the disease lesion on maize stalks by 1.5 cm and corn by 4.0 cm caused by Fusarium graminearum PH‐1. Furthermore, after treatment with melatonin, the plant defense enzymes like SOD significantly increased, while POD and APX significantly decreased compared to the control. In addition, melatonin can also improve maize's innate immunity, which is mediated by melatonin treatments through the salicylic acid signaling pathway, and up‐regulate the defense‐associated expression of PR1, LOX1, OXR, serPIN, and WIPI genes in maize. Melatonin not only inhibits the disease in the maize stalks and corn, but also down‐regulates the deoxynivalenol (DON) production‐related expression of genes Tri1, Tri4, Tri5, and Tri6 in maize. Overall, this study sheds new light on the mechanisms by which melatonin regulates antioxidant enzymes and defense‐related genes involved in plant immunity to effectively suppress plant diseases. [ABSTRACT FROM AUTHOR]

Rhizoctonia solani and Xanthomonas oryzae pv. oryzae (Xoo) are the two major diseases affecting the quality and quantity of rice production. In the current study, volatile organic compounds (VOCs) of Bacillus spp. were used as green biocontrol agents for plant diseases. In in vitro experiments, Bacillus spp. FZB42, NMTD17, and LLTC93‐VOCs displayed strong antimicrobial volatile activity with inhibition rates of 76, 66, and 78% for R. solani and 78, 81, and 76% for Xoo, respectively, compared to control. The synthetic VOCs, namely Pentadecane (PDC), Benzaldehyde (BDH), 1,2‐Benz isothiazol‐3(2H)‐one (1,2‐BIT), and mixture (MIX) of VOCs showed high volatile activity with inhibition rates of 86, 86, 89, and 92% against R. solani and 81, 81, 82, and 86%, respectively, against Xoo as compared to control. In addition, the scanning and transmission electron microscopes (SEM and TEM) analyses were performed to examine the effect of Bacillus and synthetic VOC treatments on R. solani and Xoo morphology. The analysis revealed the deformed and irregularized morphology of R. solani mycelia and Xoo cells after VOC treatments. The microscopic analysis showed that the rapid inhibition was due to severe oxidative productions inside the R. solani mycelia and Xoo cells. By using molecular docking, it was determined that the synthetic VOCs entered the active binding site of trehalase and NADH dehydrogenase proteins, causing R. solani and Xoo cells to die prematurely and an accumulation of ROS. In the greenhouse experiment, FZB42, NMTD17, and LLTC93‐VOCs significantly reduced the lesions of R. solani 8, 7, and 6 cm, and Xoo 7, 6, and 6 cm, respectively, then control. The synthetic VOCs demonstrated that the PDC, BDH, 1,2‐BIT, and MIX‐VOCs significantly reduced R. solani lesions on leaves 6, 6, 6, and 5 cm and Xoo 6, 5, 5, and 4 cm, respectively, as compared to control. Furthermore, plant defence‐related genes and antioxidant enzymes were upregulated in rice plants. These findings provide novel mechanisms by which Bacillus antimicrobial VOCs control plant diseases. [ABSTRACT FROM AUTHOR]

Volatile organic compounds (VOCs), produced by a variety of microbial species and used as biological agents, have been demonstrated to play a significant role in controlling phytopathogens. In continuation of our previous studies, we aim to elucidate the underlying mechanisms and pathways involved in interactions between pathogens and microbial VOCs. In the current study, we tested how VOCs produced by Bacillus velezensis FZB42 affect the growth of Ralstonia solanacearum TBBS1 in vitro.Query The result showed that the colony growth of R. solanacearum was reduced with an inhibition rate of 0.83 ± 0.043 as compared to the control 1.7 ± 0.076, respectively. The number of viable cells of R. solanacearum was significantly decreased to 7.68 CFU/mL as compared to the control (9.02 CFU/mL). In addition, transcriptomic analysis of R. solanacearum in response to VOCs produced by FZB42 was performed to better understand the effect of VOCs on R. solanacearum. The transcriptional response of R. solanacearum to FZB42-VOCs was determined using an Illumina RNA-seq approach. The results revealed significant changes in the expression of 2094 R. solanacearum genes, including 593 upregulated and 1501 downregulated genes. To validate the RNA-seq results, the expression of 10 genes was quantified using RT-qPCR. Furthermore, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases were used to functionally annotate differentially expressed genes. Significant changes were observed in genes directly or indirectly related to virulence, including those related to bacterial invasion, motility, chemotaxis, and secretion systems. Overall, RNA-seq profiling provides new insights into the possible fundamental molecular mechanisms that are responsible for the reduction in growth and virulence of R. solanacearum upon application of FZB42-VOC. [ABSTRACT FROM AUTHOR]

In this study, 2,6-diacetylpyridine dioxime was synthesized from 2,6-diacetylpyridine and hydroxylamine hydrochloride as raw materials and bonded into the molecular chain of waterborne polyurethane as an alcohol chain extender, Subsequent addition of Cu2+ interacted with the Schiff base structure in the WPU molecular chain to generate room-temperature self-healing polymeric materials with multiple dynamic bonds based on ligand bonds, oxime carbamates, and hydrogen bonds. Due to the synergistic effect of multiple dynamic bonds, DWPU-Cu0.25 exhibited excellent mechanical properties (tensile strength of 11.9 MPa and elongation at break of 1620%) and excellent room temperature self-healing ability (healing efficiencies of 89.1% and 95.8% for elongation at break and tensile strength, after 72 h of room temperature healing). Additionally, antibacterial experiments showed that DWPU-Cu films can release copper ions and create antibacterial zones around polyurethane films, demonstrating their use in the field of antibacterial coatings. By introducing covalent bonds and non-covalent dynamic bonds into the waterborne polyurethane to improve the healing ability of the material, and this internal self-healing method avoids the disadvantages of the external self-healing method, such as irreversibility, complex operation and poor compatibility. This self-healing mechanism based on the dynamic bond inside the material can not only realize repeated self-healing, but also have excellent basic properties, and can also expand other functions on the basis of self-repair, and realize the application of multifunctional materials. [ABSTRACT FROM AUTHOR]

Simple Summary: Microbial volatile organic compounds (VOCs) play a crucial role in promoting plant growth and causing systemic resistance to a variety of diseases caused by fungus, bacteria, nematodes, and oomycetes. However, the role of Bacillus VOCs in growth promotion is still limited. In the present work, we aim to examine the growth promotion mechanisms of cold-tolerant Bacillus strains RJGP41 and GBAC46 from the Qinghai-Tibet Plateau and the well-known PGPR strain FZB42 and their VOCs on tomato plants. Our experiment results revealed that both Bacillus isolates and their pure VOCs positively improve PGPR activities in tomato plants by triggering antioxidant enzyme activity and expression of the PGPR genes. In our future research, the selected Bacillus strains and their novel pure VOCs will be further explored to find the possible mechanisms for the safe and green control of tomato disease in sustainable agriculture. The interaction between plant and bacterial VOCs has been extensively studied, but the role of VOCs in growth promotion still needs to be explored. In the current study, we aim to explore the growth promotion mechanisms of cold-tolerant Bacillus strains GBAC46 and RJGP41 and the well-known PGPR strain FZB42 and their VOCs on tomato plants. The result showed that the activity of phytohormone (IAA) production was greatly improved in GBAC46 and RJGP41 as compared to FZB42 strains. The in vitro and in-pot experiment results showed that the Bacillus VOCs improved plant growth traits in terms of physiological parameters as compared to the CK. The VOCs identified through gas chromatography-mass spectrometry (GC-MS) analysis, namely 2 pentanone, 3-ethyl (2P3E) from GBAC46, 1,3-cyclobutanediol,2,2,4,4-tetramethyl (CBDO) from RJGP41, and benzaldehyde (BDH) from FZB42, were used for plant growth promotion. The results of the partition plate (I-plate) and in-pot experiments showed that all the selected VOCs (2P3E, CBDO, and BDH) promoted plant growth parameters as compared to CK. Furthermore, the root morphological factors also revealed that the selected VOCs improved the root physiological traits in tomato plants. The plant defense enzymes (POD, APX, SOD, and CAT) and total protein contents were studied, and the results showed that the antioxidant enzymes and protein contents significantly increased as compared to CK. Similarly, plant growth promotion expression genes (IAA4, ARF10A, GA2OX2, CKX2, and EXP1) were significantly upregulated and the ERF gene was downregulated as compared to CK. The overall findings suggest that both Bacillus isolates and their pure VOCs positively improved plant growth promotion activities by triggering the antioxidant enzyme activity, protein contents, and relative gene expressions in tomato plants. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the effects of Bacillus licheniformis and combined herbs extracts on the physiological and immune characteristics, intestinal microbiota, and vibriosis resistance of sea cucumber Apostichopus japonicus. The sea cucumbers were fed with basal diets supplemented with B. licheniformis (B group), combined herbs extracts (C group), or both (BC group). The BC group exhibited the better growth performance and higher digestive and immune enzyme activities, whereas the lowest parameters appeared in the control group. This revealed that dietary B. licheniformis and combined herbs extracts in combination could improve digestion, food intake, phosphatase-responsiveness, and oxidation resistance more efficiently compared with the other groups. The BC group was also more capable of regulating intestinal flora balance of sea cucumbers by increasing the beneficial bacteria related to energy synthesis and metabolic conversion, and inhibiting the potential pathogens associated with organic damage and metabolic disorders. Furthermore, the BC group showed greater ability of improving disease resistance by reducing the cumulative mortality rates and the counts of Vibrio splendidus. These results collectively demonstrated that dietary B. licheniformis and combined herbs extracts could improve the physiological and immune parameters, optimize the microbial community, and enhance the resistance to vibriosis of sea cucumbers, and the health-promoting effects were more obvious by supplying them in combination. [ABSTRACT FROM AUTHOR]

The plant parasitic nematode Aphelenchoides besseyi is a major pest that poses serious threats to different vegetables and crop plants. In the present study, volatiles isolated from Bacillus spp. were utilized as green biocontrol agents to overcome nematodes. In in vitro experiment, Bacillus spp. GBSC56, SYST2, and FZB42 showed the strongest nematicidal activity with killing rates of 80.78%, 75.69%, and 60.45%, respectively, as compared with control. The selected synthetic volatile organic compounds (VOCs), namely albuterol, benzaldehyde (BDH), 1,2‐benzisothiazol‐3(2H)‐one (1,2‐HIT), dimethyl disulfide (DMDS), 2‐undecanone (2‐UD), and 1,3‐propanediole (1,3‐PD), exhibited strong nematicidal activity, with A. besseyi killing rate of 85.58%, 82.65%, 81.75%, 80.36%, 84.45%, and 82.36%, respectively, at 400 μg/mL. Microscopic analysis proved that the rapid mortality was due to the production of reactive oxygen species (ROS). Molecular docking attributed this ROS production to the nematicidal effect of synthetic VOCs on NADH DEHYDROGENASE SUBUNIT 2, which is known to play a critical role in the suppression of ROS in nematode models. In a greenhouse experiment, the Bacillus strains GBSC56, SYST2, and FZB42 and their synthetic VOCs significantly improved the physiological parameters in terms of growth promotion traits. In addition, selected genes related to growth promotion and defense genes showed a significant upregulation of their expression in rice seedlings treated with those synthetic VOCs. Overall, these findings revealed that the selected Bacillus strains and their synthetic VOCs possess high potential against A. besseyi. Moreover, this study also sheds new light on the mechanisms by which specific Bacillus nematicidal VOCs influence important genes involved in rice plant growth promotion and could effectively be used to suppress plant parasitic nematodes. [ABSTRACT FROM AUTHOR]

Background: Psoriasis is a common skin inflammatory disease. Dysregulated growth and differentiation of keratinocytes are the main characteristics of psoriasis. Diosmetin is a naturally occurring flavonoid with antioxidant, anti-inflammatory, and antibacterial properties. However, the anti-psoriatic role and mechanism of diosmetin remain unclear. Objectives: To investigate anti-psoriatic role and mechanism of diosmetin. Methods: Human immortalized epidermal cells (HaCaT) were treated with tumor necrosis factor-alpha (TNF-α) to establish the cell model of psoriasis. Mice were treated with imiquimod (IMQ) to establish the animal model of psoriasis. Cell viability and apoptosis were detected by methyl thiazolyl tetrazolium and flow cytometry, respectively. Reverse transcription-quantitative polymerase chain reaction and ELISA assays were performed to detect the expression of interleukin (IL)-6 and IL-8. Hematoxylin and eosin staining was used to detect the skin lesion. Results: Diosmetin reduced cell viability and promoted the apoptosis of TNF-α-induced HaCaT. Protein expression of Bax in TNF-α-induced HaCaT was up-regulated, while Bcl-2 was down-regulated by diosmetin. Diosmetin attenuated TNF-α-induced increase in IL-6 and IL-8 in HaCaT. The enhanced protein expression of toll-like receptor 4 (TLR 4) (toll-like receptor 4), p65 and IκBα phosphorylation, as well as reduced IκBα in TNF-α-induced HaCaT were restored by diosmetin. Diosmetin improved IMQ-induced skin lesion and attenuated inflammatory response in psoriasis-like mouse model. Conclusion: Diosmetin exerted anti-inflammatory and pro-apoptotic effects on TNF-α-induced HaCaT and IMQ-induced mice through inactivation of TLR4/nuclear factor kappa B pathway. [ABSTRACT FROM AUTHOR]

The plant parasitic nematode, Aphelenchoides besseyi, is a serious pest causing severe damage to various crop plants and vegetables. The Bacillus thuringiensis (Bt) strains, GBAC46 and NMTD81, and the biological strain, FZB42, showed higher nematicidal activity against A. besseyi, by up to 88.80, 82.65, and 75.87%, respectively, in a 96-well plate experiment. We screened the whole genomes of the selected strains by protein-nucleic acid alignment. It was found that the Bt strain GBAC46 showed three novel crystal proteins, namely, Cry31Aa, Cry73Aa, and Cry40ORF, which likely provide for the safe control of nematodes. The Cry31Aa protein was composed of 802 amino acids with a molecular weight of 90.257 kDa and contained a conserved delta-endotoxin insecticidal domain. The Cry31Aa exhibited significant nematicidal activity against A. besseyi with a lethal concentration (LC50) value of 131.80 μg/mL. Furthermore, the results of in vitro experiments (i.e., rhodamine and propidium iodide (PI) experiments) revealed that the Cry31Aa protein was taken up by A. besseyi, which caused damage to the nematode's intestinal cell membrane, indicating that the Cry31Aa produced a pore-formation toxin. In pot experiments, the selected strains GBAC46, NMTD81, and FZB42 significantly reduced the lesions on leaves by up to 33.56%, 45.66, and 30.34% and also enhanced physiological growth parameters such as root length (65.10, 50.65, and 55.60%), shoot length (68.10, 55.60, and 59.45%), and plant fresh weight (60.71, 56.45, and 55.65%), respectively. The number of nematodes obtained from the plants treated with the selected strains (i.e., GBAC46, NMTD81, and FZB42) and A. besseyi was significantly reduced, with 0.56, 0.83., 1.11, and 5.04 seedling mL−1 nematodes were achieved, respectively. Moreover, the qRT-PCR analysis showed that the defense-related genes were upregulated, and the activity of hydrogen peroxide (H2O2) increased while malondialdehyde (MDA) decreased in rice leaves compared to the control. Therefore, it was concluded that the Bt strains GBAC46 and NMTD81 can promote rice growth, induce high expression of rice defense-related genes, and activate systemic resistance in rice. More importantly, the application of the novel Cry31Aa protein has high potential for the efficient and safe prevention and green control of plant parasitic nematodes. [ABSTRACT FROM AUTHOR]

Aquaculture pond sediments have a notable influence on the ecosystem balance and farmed animal health. In this study, microalgal-bacterial immobilization (MBI) was designed to improve aquaculture pond sediments via synergistic interactions. The physicochemical characteristics, bacterial communities, and the removal efficiencies of emerging pollutants were systematically investigated. The consortium containing diatom Navicula seminulum and Alcaligenes faecalis was cultivated and established in the free and immobilized forms for evaluating the treatment performance. The results indicated that the immobilized group exhibited superior performance in controlling nutrient pollutants, shaping and optimizing the bacterial community compositions with the enrichment of functional bacteria. Additionally, it showed a stronger positive correlation between the bacterial community shifts and nutrient pollutants removal compared to free cells. Furthermore, the immobilized system maintained the higher removal performance of emerging pollutants (heavy metals, antibiotics, and pathogenic Vibrios) than free group. These findings confirmed that the employment of immobilized N. seminulum and A. faecalis produced more synergistic benefits and exerted more improvements than free cells in ameliorating aquaculture pond sediments, suggesting the potential for engineering application of functional microalgal-bacterial consortium in aquaculture. [Display omitted] • The cooperative interactions of MBI for reducing nutrient pollutants were explored. • MBI performed better in improving physicochemical properties than free system. • The bacterial communities were shaped and optimized by MBI more significantly. • MBI exhibited a higher emerging pollutants removal performance than free system. [ABSTRACT FROM AUTHOR]

The rhizospheric bacterium Pseudomonas protegens Pf-5 can colonize the seed and root surfaces of plants, and can protect them from pathogen infection. Secondary metabolites, including lipopeptides and polyketides produced by Pf-5, are involved in its biocontrol activity. We isolated a crude extract from Pf-5. It exhibited significant surface activity and strong antibacterial activity against Pantoea ananatis DZ-12, which causes maize brown rot on leaves. HPLC analysis combined with activity tests showed that the polyketide pyoluteorin in the crude extract participated in the suppression of DZ-12 growth, and that the lipopeptide orfamide A was the major biosurfactant in the crude extract. Further studies indicated that the pyoluteorin in the crude extract significantly suppressed the biofilm formation of DZ-12, and it induced the accumulation of reactive oxygen species in DZ-12 cells. Scanning electron microscopy and transmission electron microscopy observation revealed that the crude extract severely damaged the pathogen cells and caused cytoplasmic extravasations and hollowing of the cells. The pathogenicity of DZ-12 on maize leaves was significantly reduced by the crude extract from Pf-5 in a dose-dependent manner. The polyketide pyoluteorin had strong antibacterial activity against DZ-12, and it has the potential for development as an antimicrobial agent. [ABSTRACT FROM AUTHOR]

Bacillus spp. has been widely used as a biocontrol agent to control plant diseases. However, little is known about mechanisms of the protein MAMP secreted by Bacillus spp. Herein, our study reported a glycoside hydrolase family 30 (GH30) protein, BpXynC, produced by the biocontrol bacteria Bacillus paralicheniformis NMSW12, that can induce cell death in several plant species. The results revealed that the recombinant protein triggers cell death in Nicotiana benthamiana in a BAK1-dependent manner and elicits an early defense response, including ROS burst, activation of MAPK cascades, and upregulation of plant immunity marker genes. BpXynC was also found to be a glucuronoxylanase that exhibits hydrolysis activity on xlyan. Two mutants of BpXynC which lost the glucuronoxylanase activity still retained the elicitor activity. The qRT-PCR results of defense-related genes showed that BpXynC induces plant immunity responses via an SA-mediated pathway. BpXynC and its mutants could induce resistance in N. benthamiana against infection by Sclerotinia sclerotiorum and tobacco mosaic virus (TMV). Furthermore, BpXynC-treated tomato fruits exhibited strong resistance to the infection of Phytophthora capsica. Overall, our study revealed that GH30 protein BpXynC can induce plant immunity response as MAMP, which can be further applied as a biopesticide to control plant diseases. • A potential protein MAMP BpXynC was isolated from Bacillus paralicheniformis NMSW12. • BpXynC elicits defense response in N. benthamiana through a BAK1 pathway. • BpXynC induces plant immunity independent of its glucuronoxylanase activity. • BpXynC doesn't impair plant growth and reduces significantly plant disease severity. [ABSTRACT FROM AUTHOR]

Phytophthora capsici is a destructive oomycete pathogen that mainly threatens solanaceous and cucurbitaceous vegetable crops, resulting in severe economic losses annually. Paenibacillus polymyxa , a typical biological control agent (BCA), has been widely used to control plant diseases due to its efficacy and environmentally friendly properties. However, the application of P. polymyxa to control pathogenic oomycete P. capsici during the postharvest period has not been reported. In this study, we found that P. polymyxa NX20 exhibited the best inhibitory effect on the mycelial growth of P. capsici among 160 cultivable isolates, and the lipopeptide fusaricidin was the main factor in its antagonistic action. Fusaricidin exhibited good inhibition activity against P. capsici with an EC 50 value of 2.46 mg L−1. Both zoospore production and germination were suppressed by fusaricidin in a dose-dependent manner. According to the microscopy observation and cell membrane permeability assay, fusaricidin was proved to impaired the plasma membrane structure and led to cell death in P. capsici. Additionally, after exposure to fusaricidin, the reactive oxygen species accumulation was induced and DNA/protein synthesis was inhibited in P. capsici. RNA-Seq analysis revealed that fusaricidin treatment could potentially affect plasma membrane integrity, transmembrane transport, energy metabolism, and signal transduction in P. capsici. Furthermore, fusaricidin exhibited good control efficacy against P. capsici on watermelon, pepper, and cherry tomato fruit. Overall, these findings elucidated the anti-oomycete mechanism of fusaricidin and highlighted the potential of P. polymyxa strain NX20 on vegetable protection and preservation. • A novel isolate Paenibacillus polymyxa NX20 displayed good biocontrol ability. • Fusaricidin was the active factor of NX20 against Phytophthora capsici. • Fusaricidin disrupted the cell plasma membrane and induced ROS accumulation. • Fusaricidin reduced significantly disease severity caused by Phytophthora capsici. [ABSTRACT FROM AUTHOR]

Summary: Biofilms are architecturally complex communities of microbial cells held together by a self‐produced extracellular matrix. Considerable research has focused on the environmental signals that trigger or inhibit biofilm formation by affecting cellular signalling pathways; however, response to soil cues in plant‐associated Bacillus has remained largely unaddressed. Therefore, we aimed to investigate the effect of Zn(II) ions in biofilm formation of Bacillus amyloliquefaciens FZB42. We demonstrated that the biofilm formation of B. amyloliquefaciens FZB42 was abolished by Zn(II) at non‐deleterious concentrations. Moreover, Zn(II) blocked matrix exopolysaccharide and TasA accumulations. Furthermore, the presence of Zn(II) suppressed expression of the response regulator Spo0F but not of sensor histidine kinases KinA‐D. Suppression of phosphorelay by excess Zn interferes with sinI induction under biofilm‐inducing conditions, leading to repression of transcription of operons epsA‐O and tapA‐sigW‐tasA. Addition of Zn(II) decreased the intracellular Mn(II) level by competing for binding to the solute‐binding protein MntA during Mn(II) uptake. These results suggest that the metal ion Zn(II) has a negative effect on biofilm formation in the plant growth promoting and biocontrol bacterium B. amyloliquefaciens FZB42. [ABSTRACT FROM AUTHOR]

Many representatives of the Bacillus subtilis species complex are known as plant growth-promoting rhizobacteria (PGPR) and are widely used in agriculture as biofertilizers and biocontrol agents. Two bacterial strains, "Korea isolate" and ZL918, taxonomically classified as being Bacillus amyloliquefaciens, isolated from disease-damaged plant organs, were alleged to cause bacterial rot in starchy storage plant organs. The aim of this study was to elucidate whether these findings have consequences for the general use of beneficial Bacilli in agriculture. Whole genome sequencing revealed that the pathogenic ZL918 was a representative of Bacillus velezensis. B. velezensis FZB42 and other representatives of the B. subtilis species complex caused the same symptoms of bacterial rot only when injected inside of potato tubers and onion bulbs, but not when inoculated onto the surface of the storage organs. It seemed that the pathogenic effect was due to starch hydrolyzing activity that likely stimulates propagation of endophytic bacteria inside of starchy tissues. After removing the inherent microbiota via Co60 γ-ray irradiation, the storage organs inoculated by either FZB42 or purified α-amylase did not develop rot symptoms. Two opportunistic pathogens, Pantoea ananatis and Pantoea agglomerans, isolated from the rotted area, were shown to cause bacterial rot in x-ray treated potato tuber and onion starchy tissues when the proteobacteria were applied in high concentration. This suggests that opportunistic pathogenic bacteria residing inside of the starchy storage organ are the causal agents of bacterial soft rot disease in potato tubers and other starchy plant storage organs. [ABSTRACT FROM AUTHOR]

Summary: Nearly 1400 Bacillus strains growing in the plant rhizosphere were sampled from different sites on the Qinghai–Tibetan Plateau. Forty‐five of the isolates, selected due to their biocontrol activity, were genome‐sequenced and their taxonomic identification revealed that they were representatives of the Bacillus subtilis species complex (20) and the Bacillus cereus group (9). Majority of the remaining strains were found closely related to Bacillus pumilus, but their average nucleotide identity based on BLAST and electronic DNA/DNA hybridization values excluded closer taxonomic identification. A total of 45 different gene clusters involved in synthesis of secondary metabolites were detected by mining the genomes of the 45 selected strains. Except eight mesophilic strains, the 37 remaining strains were found either cold‐adapted or psychrophilic, able to propagate at 10°C and below (Bacillus wiedmannii NMSL88 and Bacillus sp. RJGP41). Pot experiments performed at 10°C with winter wheat seedlings revealed that cold‐adapted representatives of B. pumilus, B. safensis and B. atrophaeus promoted growth of the seedlings under cold conditions, suggesting that these bacilli isolated from a cold environment are promising candidates for developing of bioformulations useful for application in sustainable agriculture under environmental conditions unfavourable for the mesophilic bacteria presently in use. [ABSTRACT FROM AUTHOR]

Summary: Oligosaccharide, a typical danger‐associated molecular pattern (DAMP), has been studied and applied as plant defence elicitor for several years. Here, we report a novel oligosaccharide, mannan oligosaccharide (MOS) with a degree of polymerization of 2–6, which was hydrolysed from locust bean gum by a newly reported enzyme, BpMan5. The MOS treatment can significantly enhance the generation of signalling molecules such as intracellular Ca2+ and reactive oxygen species. Subsequent defence events like stomata closure and cell death were also caused by MOS, eventually leading to the prevention of pathogen invasion or expansion. Transcriptional expression assay indicated that MOS activated mitogen‐activated protein kinase cascades in tobacco and rice via different cascading pathways. The expression levels of the defence‐related genes PR‐1a and LOX were both up‐regulated after MOS treatment, suggesting that MOS may simultaneously activate salicylic acid and jasmonic acid‐dependent signalling pathways. Furthermore, liquid chromatography‐mass spectrometry analysis showed that MOS led to the accumulation of four phytoalexins (momilactone A, phytocassane A, phytocassane D, and phytocassane E) in rice seedling leaves within 12–24 h. Finally, MOS conferred resistance in rice and tobacco against Xanthomonas oryzae and Phytophthora nicotianae, respectively. Taken together, our results indicated that MOS, a novel DAMP, could trigger multiple defence responses to prime plant resistance and has a great potential as plant defence elicitor for the management of plant disease. [ABSTRACT FROM AUTHOR]

• Genetic marker development and LC-MS analysis rapidly detected antimicrobial compounds in 47 Bacillus strains. • Only 19 Bacillus strains possessed antimicrobial compounds among the screened strains. • Bacillus strains and their methanolic extracts showed suppression of Sclerotinia sclerotiorum during in vitro assays. Bacillus strains are well studied for antagonistic effect against fungal pathogens, but the selection of potential antifungal strains is laborious and time-consuming process. Newly developed genetic markers and LC-MS based detection was undertaken simultaneously to detect eight antimicrobial compounds viz., surfactin, bacillomycin, iturin, fengycin/plipastatin, bacilysin, bacillaene, bacillibactin and plantazolicin in forty-seven Bacillus strains. Out of these strains, 19 were positive for the presence of marker genes encoding antimicrobial compounds. Bacillus strains FZB42, EZ1509, EZ1507, VM10, GBAC46, VM49 and LLCG43 possessed genes for maximum number of antimicrobial compounds. LC-MS analysis of antimicrobial compounds showed corresponding results except OKB105 and 168. Contrary to marker-based detection of genes, LC-MS analysis revealed that OKB105 can produce surfactin but unable to synthesize fengycin, while 168 was deficit in both compounds. To assay antifungal potential, 19 Bacillus strains and their methanolic extracts were tested in vitro to inhibit mycelial growth of S. sclerotiorum. Results revealed that EZ1509, VM10, GBAC46, VM49 and FZB42 showed highest inhibitory activity. A bioassay on detached rapeseed leaves demonstrated that strains VM10, EZ1509, FZB42 and GBAC46 were excellent in reducing lesion diameter, while, OKB105 and 168 were completely ineffective to control S. sclerotiorum. Interestingly, antifungal activity of Bacillus strains was positively co-related to the number of antimicrobial genes, indicating their role in antifungal activity of Bacillus strains. Our findings suggest that combining genetic markers and LC-MS analysis can rapidly screen Potential Bacillus strains with antifungal attributes and this screening method can serve as foundation for the development of new biopesticides. [ABSTRACT FROM AUTHOR]

Summary : Xanthomonas oryzae pv. oryzae (Xoo) causes a damaging bacterial leaf blight disease in rice. Cold shock proteins (Csps) are highly conserved nucleic acid‐binding proteins present in various bacterial genera, but relatively little is known about their functions in Xanthomonas. Herein, we identified four Csps (CspA–CspD) in the Xoo PXO99A strain. Deletion of cspA decreased cold adaptation and a few known pathogenic factors, including bacterial pathogenicity, biofilm formation and polysaccharide production. Furthermore, we performed transcriptomic and chromosome immunoprecipitation (ChIP) experiments to identify direct targets of CspA and to determine its DNA‐binding sequence. Integrative data analysis revealed that CspA directly regulates two genes, PXO_RS11830 and PXO_RS01060, by binding to a conserved CCAAT sequence in the promoter region. We generated single‐deletion mutants of each gene and the results indicate that both are responsible for Xanthomonas pathogenicity. In addition, quantitative real‐time polymerase chain reaction and western blotting showed that CspA suppressed the expression of its direct targets. In summary, our study clarifies the characteristics of Csps in Xanthomonas and greatly advances our understanding of the mechanisms underlying the contribution of CspA to bacterial virulence. [ABSTRACT FROM AUTHOR]

Plants live in close association with large communities of microbes, some of which are foliar pathogens that invade tissues, primarily via stomata on the leaf surface. Stomata are considered part of an integral, innate immunity system capable of efficiently preventing pathogens from entering the host plant. Although Bacillus, a typical plant growth-promoting rhizobacterium, is known to induce stomatal closure, the substances participating in this closure and the mechanism involved in its regulation remain poorly understood. Here, we screened a mutant library and conducted site-specific mutagenesis experiments in order to identify such substances. We found that acetoin and 2,3-butanediol from B. amyloliquefaciens FZB42 induced stomatal closure in Arabidopsis thaliana and Nicotiana benthamiana. These two components could function either via root absorption or volatilization to restrict stomatal apertures, but root absorption was more efficient. Both substances invoked the salicylic acid and abscisic acid signaling pathways to close the stomata and stimulated accumulation of hydrogen peroxide and nitric oxide. The results present comprehensive evidence of how soil rhizobacteria may affect plant stomata, in a way that reinforces the evolved mutualism between the two groups of organisms, and provide potential alternative avenues of research towards reducing the incidence of disease in crops. [ABSTRACT FROM AUTHOR]

Recent investigations have demonstrated that bacteria employ the volatile compounds they produce during interactions with other organisms, such as plants, fungi, nematodes and bacteria. However, studies focused on the antibacterial activity of plant growth-promoting rhizobacteria (PGPR) volatiles against bacterial phytopathogens are still rare. In this study, Bacillus strain D13, which is antagonistic to Xanthomonas oryzae pv. oryzae ( Xoo), was isolated and screened. Volatile compounds emitted from strain D13 reduced the colony diameter and cell motility of Xoo cultured in divided Petri plates. Transmission electron micrograph analysis showed concentration in cytoplasm and altered surface morphology in the majority of Xanthomonas cells after co-cultivation with strain D13. Transcriptional expression of virulence-associated genes in Xoo was repressed. Based on gas chromatography/mass spectrometry (GC/MS) analysis, 12 volatile compounds specifically produced by strain D13 were identified. Among them, decyl alcohol and 3,5,5-trimethylhexanol inhibited the growth of Xoo at minimum inhibitory amounts of 0.48 and 2.4 mg, respectively. Furthermore, transcriptional expression of virulence-associated genes was also repressed by decyl alcohol and 3,5,5-trimethylhexanol. These results are useful for a better understanding of the biocontrol mechanisms of Bacillus. [ABSTRACT FROM AUTHOR]

Histone H3 lysine 36 methylation (H3K36me) is generally associated with activation of gene expression in most eukaryotic cells. However, the function of H3K36me in filamentous fungi is largely unknown. Set2 is the sole lysine histone methyltransferase (KHMTase) enzyme responsible for the methylation of H3K36 in Saccharomyces cerevisiae . In the current study, we identified a single ortholog of S. cerevisiae Set2 in Fusarium verticillioides . We report that FvSet2 is responsible for the trimethylation of H3K36 (H3K36me3). The FvSET2 deletion mutant (ΔFvSet2) showed significant defects in vegetative growth, FB 1 biosynthesis, pigmentation, and fungal virulence. Furthermore, trimethylation of H3K36 was found to be important for active transcription of genes involved in FB 1 and bikaverin biosyntheses. These data indicate that FvSet2 plays an important role in the regulation of secondary metabolism, vegetative growth and fungal virulence in F. verticillioides. [ABSTRACT FROM AUTHOR]

In this study, a cost effective activated carbon was prepared using peanut shells as precursor material, which was used for treatment of soil eluent containing explosive contaminants. The effects of temperature, contact time, adsorbent dosage and pH were optimized by response surface methodology (RSM). The Langmuir and Freundlich adsorption isotherm models were used to fit the adsorption process of chemical oxygen demand (COD). The results showed that the maximum COD removal was obtained when temperature, time, absorbent dosage and pH were at 15 °C, 236 min, 6.06 g and 4, respectively. The adsorption of COD on activated carbon was in accord with Freundlich isotherm. Pseudo-second-order model can be used to describe the adsorption kinetics of COD. After adsorption at the optimized conditions, the chrominance reduced from 400 to 5°, COD decreased from 1012.60 to 73.51 mg L −1 , with COD removal of 92.74%, the concentrations of the two main contaminants 2, 4-dinitrotoluene-3-sulfonate (2, 4-DNT-3-SO 3 - ) and 2, 4-dinitrotoluene-5-sulfonate (2, 4-DNT-5-SO 3 - ) reduced from and 332.66 and 14.24 mg L −1 to 0 mg L −1 , respectively. The activated carbon produced from peanut shells could be a potential cost effective adsorbent for treatment of soil eluent containing explosive pollutants. [ABSTRACT FROM AUTHOR]

Plant growth-promoting rhizobacteria (PGPR) are beneficial soil microorganisms that colonize plant roots for nutritional purposes and benefit plants by increasing plant growth or reducing plant disease. To clarify the complex mechanisms underlying plant-PGPR interactions, transcriptomic analyses of the response of rice ( Oryza sativa ) 9311 to Bacillus amyloliquefaciens FZB42 were carried out using RNA-Seq technology. This resulted in the identification of 379 differentially expressed genes in rice roots and 719 in rice leaves following FZB42 interaction that are likely to be related to plant-PGPR interactions, plant stress-resistance, pathogen-resistance, growth and development and basic and energy metabolism. We focused on plant disease-resistance mechanisms induced by FZB42. Variations in the expression of crucial genes COI1 , MEKK1 , WRKY, and PR that are involved in signal transduction following plant-pathogen interaction at different interaction time points were examined. Significantly up-regulated expression of PR , LOX, and ERF genes involved in the salicylic acid, jasmonic acid, and ethylene signal transduction pathways, respectively, were detected, suggest that defense reactions in rice were induced following interaction with FZB42. Phytoalexin changes in rice induced by FZB42 were examined and momilactone A, phytocassane A, phytocassane D, phytocassane E levels were low at 12 h, rose between 24 and 48 h, suggesting a PGPR-mediated mechanism of plant pathogen resistance. The study indicated that plant responses to PGPR in multi-metabolism pathways, which includes improving plant pathogen-resistance by mediating multi-signal transduction that regulates the expression of PRs and other defense genes, as well as influencing fundamental metabolic pathways to enhance the plant’s physical condition. [ABSTRACT FROM AUTHOR]

Cyclodipeptides, formed from two amino acids by cyclodehydration, are produced naturally by many organisms, and are known to possess a large number of biological activities. In this study, we found that cyclo ( l-Pro- l-Pro) and cyclo ( d-Pro- d-Pro) (where Pro is proline) could induce defence responses and systemic resistance in Nicotiana benthamiana. Treatment with the two cyclodipeptides led to a reduction in disease severity by Phytophthora nicotianae and Tobacco mosaic virus (TMV) infections compared with controls. Both cyclopeptides triggered stomatal closure, induced reactive oxygen species production and stimulated cytosolic calcium ion and nitric oxide production in guard cells. In addition, the application of cyclodipeptides significantly up-regulated the expression of the plant defence gene PR-1a and the PR-1a protein, and increased cellular salicylic acid (SA) levels. These results suggest that the SA-dependent defence pathway is involved in cyclodipeptide-mediated pathogen resistance in N. benthamiana. We report the systemic resistance induced by cyclodipeptides, which sheds light on the potential of cyclodipeptides for the control of plant diseases. [ABSTRACT FROM AUTHOR]

Root colonization is important for the application of Plant Growth-Promoting Rhizobacteria (PGPR). Previously, chemotaxis was believed to be the major trait for colonization. However, because chemotaxis defective mutants are usually swarming impaired at the same time, in this study we clarified the roles played by swarming motility and chemotaxis in tomato root colonization by Bacillus subtilis SWR01. Tomato seeds were treated with B. subtilis SWR01 or mutants before being sown in Simons’ gnotobiotic system, and the colonization efficacy at root tips were observed after 2 weeks. Both microscopy and plate counts showed that the colonization efficacy of swarming defective and chemotaxis proficient mutants ( ΔswrA , ΔminJ and ΔsrfAC ) was about 5%–15% that of the parental strain SWR01, while the colonization efficacy of the swarming normal and chemotaxis impaired mutant ΔcheV was 78.9% that of the wild-type bacteria. These results demonstrate that while both chemotaxis and swarming motility are important in root colonization, and the role played by swarming is greater than that of chemotaxis. In addition, non-flagellated mutants ( Δhag ) showed 0.47% colonization efficacy relative to that of B. subtilis SWR01, suggesting more than 99% root colonization requires the presence of flagella. This study indicates new ways to enhance PGPR rhizoplane colonization, which is useful in agricultural applications. [ABSTRACT FROM AUTHOR]

Heavy metal remediation, such as cadmium (Cd2+) by microbial strains is efficient and environment-friendly. In this current study, we exploited the potential of Bacillus strains (Cd2+-tolerant; NMTD17, GBSW22, and LLTC96) to regulate Cd2+ biosorption mechanisms and improve rice seedling growth. The results showed that initial concentration and contact time affected Cd2+ biosorption, and the kinetic models of pseudo orders were effective in the elaborate biosorption process. Mainly, the bacterial cell wall had the potential for Cd2+ biosorption, and we found non-significant biosorption alterations among bacterial strains' inner and outer surfaces of cell membranes. Furthermore, the Fourier transform infrared (FTIR) spectroscopy analysis identified the differences in functional groups, such as C–N, PO 2 , –SO 3 , C O, COOH, C–O, C–N, –OH, and –NH that interact in biosorption by Bacillus strains. The scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) examination revealed that the binding of Cd2+ to microbes was mostly based on ion exchange pathways. Moreover, the Bacillus strains responded to Cd2+ stress in rice under pot experiment at various concentrations (0, 0.25, and 0.50 mg kg−1), and they also influenced the chlorophyll contents and antioxidants activities were studied. The analysis of physio-morphological parameters was observed to be increased, which indicated that all Bacillus strains showed significant effects on rice growth under Cd2+ stress. These results revealed that the selected strains had the capability for additional use in the development of Cd2+ bioremediation methods. These strains also provided plant growth-promoting (PGP) traits that can alleviate the harmful effects of Cd2+ in rice plants. [Display omitted] • Bacillus sp. increased adsorption of Cd2+ on the cell wall. • Lterations in functional groups that were involved in Bacillus -Cd2+ biosorption. • Bacillus microbial strains increased Cd2+ immobilization in soil. • Microbial strains reduced Cd2+ content and improved plant growth. • Suitable microbial species that may be modified to enhance Cd2+ biosorption. [ABSTRACT FROM AUTHOR]

A novel thermostable mannanase from a newly isolated Bacillus pumilus GBSW19 has been identified, expressed, purified and characterized. The enzyme shows a structure comprising a 28 amino acid signal peptide, a glycoside hydrolase family 5 (GH5) catalytic domain and no carbohydrate-binding module. The recombinant mannanase has molecular weight of 45 kDa with an optimal pH around 6.5 and is stable in the range from pH 5–11. Meanwhile, the optimal temperature is around 65 °C, and it retains 50% relative activity at 60 °C for 12 h. In addition, the purified enzyme can be activated by several ions and organic solvents and is resistant to detergents. Bpman5 can efficiently convert locus bean gum to mainly M2, M3 and M5, and hydrolyze manno-oligosaccharides with a minimum DP of 3. Further exploration of the optimum condition using HPLC to prepare oligosaccharides from locust bean gum was obtained as 10 mg/ml locust bean gum incubated with 10 U/mg enzyme at 50 °C for 24 h. By using this enzyme, locust bean gum can be utilized to generate high value-added oligosaccharides with a DP of 2–6. [ABSTRACT FROM AUTHOR]

Bacillus amyloliquefaciens strains FZBREP and FZBSPA were derived from the wild-type FZB42 by replacement of the native bacilysin operon promoter with constitutive promoters P and P from plasmids pMK3 and pLOSS, respectively. These strains contained two antibiotic resistance genes, and markerless strains were constructed by deleting the chloramphenicol resistance cassette and promoter region bordered by two lox sites ( lox71 and lox66) using Cre recombinase expressed from the temperature-sensitive vector pLOSS-cre. The vector-encoded spectinomycin resistance gene was removed by high temperature (50 °C) treatment. RT-PCR and qRT-PCR results indicated that P and especially P significantly increased expression of the bac operon, and FZBREP and FZBSPA strains produced up to 170.4 and 315.6 % more bacilysin than wild type, respectively. Bacilysin overproduction was accompanied by enhancement of the antagonistic activities against Staphylococcus aureus (an indicator of bacilysin) and Clavibacter michiganense subsp. sepedonicum (the causative agent of potato ring rot). Both the size and degree of ring rot-associated necrotic tubers were decreased compared with the wild-type strain, which confirmed the protective effects and biocontrol potential of these genetically engineered strains. [ABSTRACT FROM AUTHOR]

Bacterial leaf pustule (BLP), caused by Xanthornonas axonopodis pv. glycines (Xag), is a worldwide disease of soybean, particularly in warm and humid regions. To date, little is known about the underlying molecular mechanisms of BLP resistance. The only single recessive resistance gene rxp has not been functionally identified yet, even though the genotypes carrying the gene have been widely used for BLP resistance breeding. Using a linkage mapping in a recombinant inbred line (RIL) population against the Xag strain Chinese C5, we identified that quantitative trait locus (QTL) qrxp–17–2 accounted for 74.33% of the total phenotypic variations. We also identified two minor QTLs, qrxp–05–1 and qrxp–17–1, that accounted for 7.26% and 22.26% of the total phenotypic variations, respectively, for the first time. Using a genome-wide association study (GWAS) in 476 cultivars of a soybean breeding germplasm population, we identified a total of 38 quantitative trait nucleotides (QTNs) on chromosomes (Chr) 5, 7, 8, 9,15, 17, 19, and 20 under artificial infection with C5, and 34 QTNs on Chr 4, 5, 6, 9, 13, 16, 17, 18, and 20 under natural morbidity condition. Taken together, three QTLs and 11 stable QTNs were detected in both linkage mapping and GWAS analysis, and located in three genomic regions with the major genomic region containing qrxp_17_2. Real-time RT-PCR analysis of the relative expression levels of five potential candidate genes in the resistant soybean cultivar W82 following Xag treatment showed that of Glyma.17G086300, which is located in qrxp–17–2, significantly increased in W82 at 24 and 72 h post-inoculation (hpi) when compared to that in the susceptible cultivar Jack. These results indicate that Glyma.17G086300 is a potential candidate gene for rxp and the QTLs and QTNs identified in this study will be useful for marker development for the breeding of Xag-resistant soybean cultivars. [ABSTRACT FROM AUTHOR]

Highlights: [•] We introduce a new soybean lectin gene (lec-s) into tobacco plants. [•] We examine transgenic tobacco plants’ resistance to pathogens and pests [•] The transgenic plants could resist to the infection of Phytophthora nicotianae. [•] The transgenic plants reduce the weight gain of Spodoptera exigua larvae. [•] The transgenic plants retard S. exigua larvae's development and metamorphosis. [Copyright &y& Elsevier]

This study elaborates inter-kingdom signaling mechanisms, presenting a sustainable and eco-friendly approach to combat biotic as well as abiotic stress in wheat. Fusarium graminearum is a devastating pathogen causing head and seedling blight in wheat, leading to huge yield and economic losses. Psychrophilic Bacillus atrophaeus strain TS1 was found as a potential biocontrol agent for suppression of F. graminearum under low temperature by carrying out extensive biochemical and molecular studies in comparison with a temperate biocontrol model strain Bacillus amyloliquefaciens FZB42 at 15 and 25 °C. TS1 was able to produce hydrolytic extracellular enzymes as well as antimicrobial lipopeptides, i.e., surfactin, bacillomycin, and fengycin, efficiently at low temperatures. The Bacillus strain-induced oxidative cellular damage, ultrastructural deformities, and novel genetic dysregulations in the fungal pathogen as the bacterial treatment at low temperature were able to downregulate the expression of newly predicted novel fungal genes potentially belonging to necrosis inducing protein families (fgHCE and fgNPP1). The wheat pot experiments conducted at 15 and 25 °C revealed the potential of TS1 to elicit sudden induction of plant defense, namely, H2O2 and callose enhanced activity of plant defense-related enzymes and induced over-expression of defense-related genes which accumulatively lead to the suppression of F. graminearum and decreased diseased leaf area. [ABSTRACT FROM AUTHOR]

Fusarium graminearum and Fusarium verticillioides are fungal pathogens that cause diseases in cereal crops, such as Fusarium head blight (FHB), seedling blight, and stalk rot. They also produce a variety of mycotoxins that reduce crop yields and threaten human and animal health. Several strategies for controlling these diseases have been developed. However, due to a lack of resistant cultivars and the hazards of chemical fungicides, efforts are now focused on the biocontrol of plant diseases, which is a more sustainable and environmentally friendly approach. In the present study, the lipopeptide mycosubtilin purified from Bacillus subtilis ATCC6633 significantly suppressed the growth of F. graminearum PH-1 and F. verticillioides 7600 in vitro. Mycosubtilin caused the destruction and deformation of plasma membranes and cell walls in F. graminearum hyphae. Additionally, mycosubtilin inhibited conidial spore formation and germination of both fungi in a dose-dependent manner. In planta experiments demonstrated the ability of mycosubtilin to control the adverse effects caused by F. graminearum and F. verticillioides on wheat heads and maize kernels, respectively. Mycosubtilin significantly decreased the production of deoxynivalenol (DON) and B-series fumonisins (FB1, FB2 and FB3) in infected grains, with inhibition rates of 48.92, 48.48, 52.42, and 59.44%, respectively. The qRT-PCR analysis showed that mycosubtilin significantly downregulated genes involved in mycotoxin biosynthesis. In conclusion, mycosubtilin produced by B. subtilis ATCC6633 was shown to have potential as a biological agent to control plant diseases and Fusarium toxin contamination caused by F. graminearum and F. verticillioides. [ABSTRACT FROM AUTHOR]

Fusarium graminearum is a destructive fungal pathogen that threatens the production and quality of wheat, and controlling this pathogen is a significant challenge. As the cost-effective homolog of melatonin, 5-methoxyindole showed strong activity against F. graminearum. In the present study, our results showed the strong adverse activity of 5-methoxyindole against F. graminearum by inhibiting its growth, formation, and conidia germination. In addition, 5-methoxyindole could induce malformation, reactive oxygen species (ROS) accumulation, and cell death in F. graminearum hyphae and conidia. In response to 5-methoxyindole, F. graminearum genes involved in scavenging reactive oxygen species were significantly downregulated. Overall, these findings reveal the mechanism of antifungal action of melatonin-homolog 5-methoxyindole. To the best of our knowledge, this is the first report that a novel melatonin homolog confers strong antifungal activity against F. graminearum, and 5-methoxyindole is a potential compound for protecting wheat plants from F. graminearum infection. [ABSTRACT FROM AUTHOR]