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

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*

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

The dominant gene Xa21 with broad-spectrum and high resistance to Xanthomonas oryzae pv. oryzae (Xoo) was transferred into C418, an important restorer line of japonica hybrid rice in China using double right-border (DRB) T-DNA binary vector through Agrobacterium-mediated transformation. 17 transgenic lines were Xa21-positive with high resistance to the race P6 of Xoo through PCR analysis and resistance identification, among the total 27 independent primary transformants (T0) obtained. The subsequent analysis of the T1 progenies of these 17 T0 lines through PCR-assisted selection and resistance investigation showed that four Xa21 transgenic T0 lines could produce selectable marker-free (SMF) progenies. The frequency of primary transformants producing SMF progenies was 15%. In addition, PCR analysis also revealed these SMF progenies did not contain vector backbone sequence, and they were named as SMF and vector backbone sequence-free (SMF-VBSF) Xa21 transgenic plants. The further molecular and phenotypic analysis of the T2 and T3 progenies testified the homozygous SMF-VBSF Xa21 transgenic plants were obtained with high resistance to Xoo.
DNA, Bacterial ; genetics ; Genetic Vectors ; Oryza ; genetics ; Plant Proteins ; genetics ; Plants, Genetically Modified ; genetics ; Protein-Serine-Threonine Kinases ; genetics ; Rhizobium ; genetics ; Transformation, Genetic ; Xanthomonas

The mutant population of Xanthomonas oryzae pv oryzae strain differential to rice bacterial blight resistance gene Xa23 has been constructed mediated by transposon in vivo . The results of PCR amplification with specific primers and analysis of flanking sequence of mutants indicated that the foreign DNA has been integrated into X. oryzae pv oryzae genome. Four mutants with changed avirulent activity to Xa23 gene have been identified by artificial inoculation. It is possible to clone genes that are required for AvrXa23 avirulence activity using this new strategy.
Bacterial Proteins ; genetics ; Base Sequence ; DNA Transposable Elements ; Gene Expression Regulation, Plant ; Genes, Plant ; Molecular Sequence Data ; Mutation ; Oryza ; genetics ; microbiology ; Plant Diseases ; microbiology ; Plants, Genetically Modified ; genetics ; microbiology ; Virulence ; Xanthomonas ; genetics ; pathogenicity ; physiology

In October 2003, a new bacterial disease with symptoms similar to those caused by Xanthomonas axonopodis pv. poinsettiicola was observed on poinsettia leaves at a flower nursery in Zhejiang Province of China. Three Xanthomonas strains were isolated from infected plants and classified as X. axonopodis. They were differentiated from the pathotype strain LMG849 of X. axonopodis pv. poinsettiicola causing bacterial leaf spot of poinsettia by comparison of pathogenicity, substrate utilization and BOX-PCR genomic fingerprints.
Cell Differentiation ; China ; Euphorbia ; microbiology ; Plant Diseases ; microbiology ; Plant Leaves ; microbiology ; Species Specificity ; Xanthomonas ; classification ; genetics ; isolation & purification ; pathogenicity

Xanthomonas campestris pv. campestris (Xcc), the pathogenic agent of black rot disease in cruciferous plants, produces large amount of extracellular polysaccharide (EPS), which has found wide applications in industry. For the great commercial value of the xanthan gum, many of the genes involved in EPS biosynthesis have been cloned and the mechanism of EPS biosynthesis also has been studied. In order to clone genes involved in EPS biosynthesis, Xcc wild-type strain 8004 was mutagenized with transposon Tn5 gusA5, and a number of EPS-defective mutants were isolated in our previous work. The Tn5 gusA5 inserted sites of these mutants were located by using thermal asymmetric interlaced PCR, and results showed that two EPS-defective mutants were insertion mutants of the gene wxcA which involved in lipopolysaccharide (LPS) biosynthesis. The gene wxcA involved in lipopolysaccharide biosynthesis but dose not extracellular polysaccharide in others' report. wxcA::Tn5 gusA5 mutant 021C12, the polar mutant, was complemented with recombinant plasmid pLATC8570 harboring an intact wxcA gene in this work, but the yield of EPS of the wxcA::Tn5 gusA5 mutant was not restored. In order to identify the function of wxcA gene of Xcc 8004 strain, the gene wxcA was deleted by gene replacement strategy, and the no-polar mutant of wxcA was obtained. DeltawxcA mutant strain, named Xcc 8570, was confirmed by using both PCR and southern analysis. Beside the LPS biosynthesis of deltawxcA mutant was affected, The EPS yield of deltawxcA mutant strain reduced by 50% as compared with the wild-type strain 8004. DeltawxcA mutant could be complemented in trans with the intact wxcA gene, and the EPS yield of the mutant was restored. The combined data showed that wxcA gene not only involved in LPS biosynthesis but also EPS yield in Xcc 8004 strain.
Cell Proliferation ; Genes, Bacterial ; physiology ; Lipopolysaccharides ; biosynthesis ; Mutation ; Polysaccharides, Bacterial ; biosynthesis ; Xanthomonas campestris ; genetics