Iron is an essential element for living organisms that plays critical roles in the process of bacterial growth and metabolism. However, it remains to be elucidated whether piuB encoding iron-uptake factor is involved in iron uptake and pathogenicity of Xanthomonas axonopodis pv. glycines (Xag). To investigate the function of piuB, we firstly generated a piuB deletion mutant (ΔpiuB) by homologous recombination. Compared with the wild-type, the piuB mutant exhibited significantly reduced growth and virulence in host soybean. The mutant displayed markedly increased siderophore secretory volume, and its sensitivity to Fe³⁺, Cu²⁺, Zn²⁺ and Mn²⁺ was significantly enhanced. Additionally, the H₂O₂ resistance, exopolysaccharide yield, biofilm formation, and cell mobility of ΔpiuB were significantly diminished compared to that of the wild-type. The addition of exogenous Fe³⁺ cannot effectively restore the above characteristics of ΔpiuB. However, expressing piuB in trans rescued the properties lost by ΔpiuB to the levels in the wild-type. Taken together, our results demonstrated that PiuB is a potential factor for Xag to assimilate Fe³⁺, and is necessary for Xag to be pathogenic in host soybean.
Iron ; Glycine max ; Virulence ; Xanthomonas axonopodis/genetics* ; Hydrogen Peroxide

In this study, a new Bacillus velezensis strain Bv-303 was identified and its biocontrol effect against rice bacterial-blight (BB) disease caused by Xanthomonas oryzae pv. oryzae (Xoo) was investigated. Cell-free supernatant (CFS) of strain Bv-303 under different growth conditions were prepared to test the antagonistic activity and stability against Xoo by the Oxford-cup method in vitro. The antibacterial effect of strain Bv-303 to BB disease in rice were further analyzed in vivo by spraying the cell-culture broth (CCB), CFS and cell-suspension water (CSW), respectively, on the rice leaves inoculated with Xoo. Additionally, rice seeds germination rate and seedling growth under the strain Bv-303 CCB treatment were tested. The results showed that the strain Bv-303 CFS significantly inhibited Xoo growth by 85.7%‒88.0% in vitro, which was also stable under extreme environment conditions such as heat, acid, alkali and ultraviolet light. As tested in vivo, spraying the CCB, CFS or CSW of strain Bv-303 on the Xoo-infected leaves enhanced rice plant resistance to BB disease, with CCB showing the highest increase (62.7%) in disease-resistance. Notably, CCB does not have negative effects on rice seed germination and seedling growth. Therefore, strain Bv-303 has great potential for biocontrol of the rice BB disease.
Oryza ; Fatigue Syndrome, Chronic ; Bacillus ; Xanthomonas ; Plant Diseases/microbiology*

Aims: This study was aimed to evaluate the potential of several carriers to formulate the phages and retain their activity under various pH and temperature conditions. Methodology and results: The skim milk, rice flour, corn flour and CalnuXan (calcium and magnesium) as carriers to formulate the isolated phage to maintain its activity under extreme pH and temperature conditions. Two phages formulated with carriers retained their viability at pH 5, pH 7 and pH 9 compared to that of the unformulated phages. Besides, the formulated phages also retained a high titre compared to the unformulated phages when they were exposed to 37 °C and 45 °C. Based on the in vitro study of the formulation, it was applied in the glass house. The plant height, leaf chlorophyll and disease scoring were recorded and analyzed. In the glass house, the rice plant treated with formulated phages showed higher plant height and chlorophyll content than those treated with unformulated or untreated phages. Nonetheless, both formulated and unformulated protected the rice plant, which showed lower disease severity than the untreated group. Conclusion, significance and impact of study Phage therapy has been used for treating plant diseases caused by pathogenic bacteria. Despite their effectiveness in killing the pathogen in vitro, the results were not reproducible in the field. Bacteriophages (phages) are sensitive to environmental factors and infection efficiency was dropped when exposed to harmful environments. However, this study successfully formulated two novels Xanthomonas phages, as biocontrol agents against bacterial leaf blight (BLB) disease in rice.
Xanthomonas ; Bacteriophages

Xanthomonas albilineans (Ashby) Downson is a quarantine pest for importing plants to China that causes leaf scald bacterial disease on sugarcane. X. albilineans produces a potent phytotoxin/antibiotic called albicidin. As a pathogenic factor, albicidin causes typical white leaf stripes by inhibiting plastid DNA gyrase and disturbing chloroplast differentiation. Meanwhile, the antibacterial activity of albicidin gives X. albilineans a competitive advantage against rival bacteria during their colonization. Furthermore, albicidin has a rapid bactericidal activity against a variety of Gram-positive and Gram-negative pathogenic bacteria of human species at nanomolar concentrations, making it a potential antimicrobial drug for clinical application. This article reviews the advances of albicidin from the aspects of its molecular structure, traditional extraction methods, mechanism of action, biosynthetic genes and processes, chemical synthesis method and improvement, in order to provide insights into the prevention and treatment of the sugarcane leaf scald disease, and the development of new antibiotics.
Anti-Bacterial Agents/pharmacology* ; China ; Humans ; Organic Chemicals ; Xanthomonas/genetics*

MarR family transcription regulators are ubiquitous among bacteria and archaea. They extensively control multiple cellular processes and elaborately regulate the expression of genes involved in virulence, stress response and antibiotics at translational level. In Xanthomonas campestris pv. campestris, insertional inactivation of MarR family transcription regulator HpaR (XC2827) resulted in significantly decrease in virulence and increase in the production of the extracellular proteases. Here, we reported that the genome of Xcc 8004 encodes nine MarR family transcription regulators. The MarR family transcription regulators, HpaR (XC2827) and XC0449, were heterologous expressed and purified. In vitro MST and Pull-down assay confirmed the physical interaction between HpaR and XC0449. Phenotypical assay determined that deletion of XC0449 resulted in substantial virulence attenuation. In vitro EMSA, in vivo qRT-PCR and GUS activity assay identified that HpaR and XC0449 coordinately act as the transcriptional activator to regulate the expression of the virulence-associated gene XC0705, and eventually control the bacterial virulence and the production of extracellular proteases.
Bacterial Proteins ; Gene Expression Regulation, Bacterial ; Transcription Factors ; Virulence ; Xanthomonas campestris

Culture filtrates of six different edible mushroom species were screened for antimicrobial activity against tomato wilt bacteria Ralstonia solanacearum B3. Hericium erinaceus, Lentinula edodes (Sanjo 701), Grifola frondosa, and Hypsizygus marmoreus showed antibacterial activity against the bacteria. Water, n-butanol, and ethyl acetate extracts of spent mushroom substrate (SMS) of H. erinaceus exhibited high antibacterial activity against different phytopathogenic bacteria: Pectobacterium carotovorum subsp. carotovorum, Agrobacterium tumefaciens, R. solanacearum, Xanthomonas oryzae pv. oryzae, X. campestris pv. campestris, X. axonopodis pv. vesicatoria, X. axonopodis pv. citiri, and X. axonopodis pv. glycine. Quantitative real-time PCR revealed that water extracts of SMS (WESMS) of H. erinaceus induced expressions of plant defense genes encoding beta-1,3-glucanase (GluA) and pathogenesis-related protein-1a (PR-1a), associated with systemic acquired resistance. Furthermore, WESMS also suppressed tomato wilt disease caused by R. solanacearum by 85% in seedlings and promoted growth (height, leaf number, and fresh weight of the root and shoot) of tomato plants. These findings suggest the WESMS of H. erinaceus has the potential to suppress bacterial wilt disease of tomato through multiple effects including antibacterial activity, plant growth promotion, and defense gene induction.
1-Butanol ; Agaricales* ; Agrobacterium tumefaciens ; Bacteria ; Glycine ; Grifola ; Lycopersicon esculentum* ; Oryza ; Pectobacterium carotovorum ; Plants ; Ralstonia solanacearum ; Real-Time Polymerase Chain Reaction ; Seedlings ; Shiitake Mushrooms ; Water* ; Xanthomonas

To explore the enzymatic route of cefatrizine synthesis, alpha-amino acid ester hydrolase (AEH) gene was cloned from the whole genome of Xanthomonas rubrillineans, and expressed heterologously in Escherichia coli BL21 (DE3). The effects of temperature, pH and substrates' molar ratio upon the transformation yield of cefatrizine by purified recombinant AEH were investigated. The monomer of AEH was determined as 70 kDa by SDS-PAGE. The optimal pH and temperature reaction were (6.0 +/- 0.1) and 36 degrees C for cefatrizine synthesis. The transformation yield was 64.3% under 36 degrees C, pH (6.0 +/- 0.1), when the concentrations of two substrates were about 30 mmol/L (7-ATTC) and 120 mmol/L (HPGM x HCl), respectively, and the enzyme consumption was 22 U/mL. The results pave the way for optimization of the industrial enzymatic synthesis of cefatrizine.
Carboxylic Ester Hydrolases ; biosynthesis ; genetics ; Catalysis ; Cefatrizine ; metabolism ; Cloning, Molecular ; Escherichia coli ; genetics ; metabolism ; Kinetics ; Recombinant Proteins ; biosynthesis ; genetics ; Xanthomonas ; enzymology

The preliminary role of respiratory burst oxidase homolog (Rboh) in plant immune response is defined, but the exact function of OsRboh gene in rice immune response and its expression pattern is yet unclear. In order to clarify the role of OsRboh in rice immune response, we screened seven OsRboh genes from the latest rice genome annotation database. The result of tissue specific expression analysis demonstrated that OsRbohD was expressed only in spike and calli, and OsRbohE and OsRbohF were only expressed in calli. The rest of OsRboh genes were constitutively expressed in rice. In addition, the expression level of OsRboh gene family was analyzed in the rice leaves respectively treated with salicylic acid (SA), methyl jasmonic acid (MeJA) and Xanthomonas oryzae PV. oryzae (Xoo) PXO99 strain by Real-time PCR, and H2O2 content was also quantified by spectrophotometry after the three treatments. The result shows that the expression of OsRbohA, B, C and D was increased under the treatments of SA, the expression of OsRbohA, B, C and G was increased under the treatments of MeJA, and the expression of OsRbohA and OsRbohB was induced by Xoo PXO99 strain. However, the levels of expression and responsive times of these genes were different. Moreover, all three treatments led to H2O2 accumulation. These OsRboh genes have functional roles in rice native immune response.
Acetates ; pharmacology ; Amino Acid Sequence ; Cyclopentanes ; pharmacology ; Hydrogen Peroxide ; metabolism ; Molecular Sequence Data ; Multigene Family ; NADPH Oxidases ; genetics ; immunology ; metabolism ; Oryza ; genetics ; immunology ; metabolism ; Oxylipins ; pharmacology ; Plant Immunity ; genetics ; Salicylic Acid ; pharmacology ; Xanthomonas ; pathogenicity

As the pathogenic bacterial virulence and avirulence factors, transcription activator like (TAL) effectors of Xanthomonas can resulted in the host diseases or resistance responses. TAL effectors can specifically bind the target DNA of host plant with a novel protein-DNA binding pattern in which two amino acids recognize one nucleotide. The complexities of TAL-DNA binding have the feasibility in use of gene therapy through homologous recombination and site-specific mutation. By using the molecular recognition code between TAL-effectors and host target genes, we can exploit both the susceptible and resistance genes; broad spectrum resistance induced by multiple TAL effectors could also be manipulated. Deeper insight in the area of protein-DNA binding mechanism will benefit the application in the biomedical engineering and agricultural engineering. This article reviews the findings and functions of TAL effectors, the binding specificity and recognition code between TAL-effectors and host target genes. The possible applications and future prospects of the molecular recognition code have been discussed.
Base Sequence ; DNA, Plant ; metabolism ; Genes, Plant ; Genetic Code ; genetics ; Host-Pathogen Interactions ; Molecular Sequence Data ; Plant Diseases ; genetics ; prevention & control ; Transcriptional Activation ; Virulence Factors ; genetics ; metabolism ; Xanthomonas ; genetics ; pathogenicity

Rice bacterial leaf streak,caused by Xanthomonas oryzae pv. oryzicola is a destructive bacterial disease in China. Single-gene resistance to X. oryzae pv. oryzicola has not been found in rice germplasm. A cloned non-host gene from maize with resistance to bacterial leaf streak, Rxo1, was transferred into four Chinese rice varieties through an Agrobacterium-mediated system, including Zhonghua11, 9804, C418 and Minghui86. PCR and Southern analysis of the transgenic plants revealed the integration of the Rxo1 gene into the rice genomes. The integrated Rxo1 was stably inherited, and segregated in a 3:1 (Resistance:Susceptible) ratio in the selfed T1 generations derived from some T0 plants, indicating that Rxo1 inherited as a dominate gene in rice. Transgenic T0 plants and PCR-positive T1 plants were resistant to X. oryzae pv. oryzicola on the basis of artificial inoculation.
Bacterial Proteins ; genetics ; metabolism ; Genes, Plant ; genetics ; Oryza ; genetics ; Plant Diseases ; genetics ; microbiology ; Plants, Genetically Modified ; genetics ; Rhizobium ; genetics ; Transformation, Genetic ; Xanthomonas ; genetics ; Zea mays ; genetics ; microbiology