• Microbiology and Biotechnology Letters
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• v.32 no.3
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• pp.256-264
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• 2004

A new primer set was developed for the detection and identification of Xanthomonas oryzae pv. oryzae, the bacterial leaf blight (BLB) pathogen in rice plant. The nucleotide sequence of hpaA gene was determined from X. o. pv. oryzae str. KACC10331, and the sequence information was used to design primers for the application of the polymerase chain reaction (PCR). The nucleotide sequence of hpaA from X. o. pv. oryzae str. KACC 10331 was aligned with those of X. campestris pv. vesicatoria, X. campestris pv. campestris, X. axonopodis pv. citri, and X. axonopodis pv. glycines. Based on these results, a primer set(XOF and XOR) was designed for the specific detection of hpaA in X. o. pv. oryzae. The length of PCR products amplified using the primer set was 534-bp. The PCR product was detected from only X. o. pv. oryzae among other Xanthomonas strains and reference bacteria. This product was used to confirm the conservation of hpaA among Xanthomonas strains by Southern-blotting. Furthermore, PCR amplification with XOF and XOR was used to detect the pathogen in an artificially infected leaf. The sensitivity of PCR detection in the pure culture suspension was also determined. This PCR-based detection methods will be a useful method for the detection and identification of X. o. pv. oryzae as well as disease forecasting.

• Journal of Microbiology and Biotechnology
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• v.18 no.9
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• pp.1492-1495
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• 2008

Successful control of Xanthomonas oryzae pv. oryzicola, the causal agent of bacterial leaf streak, requires a specific and reliable diagnostic tool. A pathovar-specific PCR assay was developed for the rapid and accurate detection ofthe plant pathogenic bacterium Xanthomonas oryzae pv. oryzicola in diseased plant. Based on differences in a membrane fusion protein gene of Xanthomonas oryzae pv. oryzicola and other microorganisms, which was generated from NCBI (http://www.ncbi.nlm.nih.gov/) and CMR (http://cmr.tigr.org/) BLAST searches, one pair of pathovar-specific primers, XOCMF/XOCMR, was synthesized. Primers XOCMF and XOCMR from a membrane fusion protein gene were used to amplity a 488-bp DNA fragment. The PCR product was only produced from 4 isolates of Xanthomonas oryzae pv. oryzicola among 37 isolates of other pathovars and species of Xanthomonas, Pectobacterium, Pseudomonas, Burkholderia, Escherichia coli, and Fusarium oxysporum f.sp. dianthi. The results suggested that the assay detected the pathogen more rapidly and accurately than standard isolation methods.

• Korean Journal of Microbiology
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• v.44 no.1
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• pp.1-9
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• 2008

Xanthomonas oryzae pv. oryzae (Xoo) is the causal agent of bacterial blight on rice. In this paper, current status on molecular genetic study of major virulence genes, hypersensitive response and pathogenicity (hrp), productions of extracellular polysaccharide (EPS), extracellular enzymes and lipopolysaccharides (LPS), avr genes were reviewed. The IS elements with 611 copies including 133 ORF IS were inserted in various regions of the Xoo genome and in expecially regions franking virulence genes. Whole genome sequence of X. oryzae pv. oryzae KACC10331 were used for defining genetic organization of the virulence genes. Futhermore, the virulence genes in Xoo genome were compared to those of other Xanthomonas species in Blast GenBank data base.

• Korean Journal Plant Pathology
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• v.10 no.1
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• pp.13-17
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• 1994

A semiselective agar medium (XCO) was developed for the isolation of bacterial blight pathogen, Xanthomonas campestris pv. oryzae, from rice seed. The medium contained yeast extract 1.0 g, peptone 2.0 g, sucrose 5.0 g, sodium glutamate 1.0 g, FeSO4.7H2O 0.05 g, Fe.EDTA 1 mg, cephalexin 20 mg, Evan blue (0.1%) 1.5 ml, bromcresol purple (0.1%) 2.5ml, cycloheximide 100 mg and agar 15.0 g per liter. Colonies of X. c. pv. oryzae were 4~5 mm in diameter, smooth, round, blue (darker center) and convex after 6 days incubation at 28$^{\circ}C$. The recovery of 6 isolates of X. c. pv. oryzae on the XOC medium ranged from 81% to 120% (mean 98.2%) in comparison to Wakimoto's medium. The number of saprophytic bacteria from 10 rice seed lots on XCO medium was reduced to 70.4% of that on Wakimoto's medium. The recovery of X. c. pv. oryzae added to rice seed on XOC medium ranged from 67% to 87% (mean 75.6%) of that on Wakimoto's medium.

• The Plant Pathology Journal
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• v.27 no.1
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• pp.26-32
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• 2011

Plant-pathogenic bacteria including Xanthomonas spp. carry genetic diversity in composition of avirulence genes for interaction with their host plants. Previously, we reported genetic diversity of avirulence genes in X. axonopodis pv. glycines. In this study, we determined genetic diversity of five avirulence genes, avrBs1, avrBs2, avrBs3, avrBs4, and avrRxv, in three other Xanthomonas species isolated in Korea by genomic southern hybridization. Although Korean races of X. campestris pv. vesicatoria that were isolated from year 1995 to 2002 had the same avirulence gene patterns as those that already reported, there was race shift from race 3 to race 1 by acquisition of avrBs3 genes. X. campestris pv. campestris isolated from Chinese cabbage, but not from cabbage or radish, carried two avrBs3 genes, and one of them affected HR-eliciting ability of this bacterium in broccoli. X. oryzae pv. oryzae carried eight to thirteen avrBs3 gene homologs, and this bacterium showed dynamic changes of resistance patterns in rice probably by losing or obtaining avrBs3 genes. These results indicate that avrBs3 gene is more diverse in Xanthomonas spp. than other four avirulence genes and also host ranges of these bacteria can be easily changed by loss or acquisition of avrBs3 genes.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.55 no.4
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• pp.306-311
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• 2010

The multiplication and movement of Xanthomonas oryzae pv. oryzae in rice leaves of seven near-isogenic lines(NILs) derived from different genetic sources and from the susceptible cultivar Toyonishiki were examined. The bacterium populations increased rapidly in susceptible cultivar leaves of the inoculation sites but increased gradually in NIL leaves. X oryzae pv. oryzae were detected at 20cm above the leaves of the inoculated sites in IRBB 103 and Toyonishiki but were not detected in the other NILs at 25 days after inoculation. These results support that resistant genes restrict bacterial movement not multiplication.

• The Plant Pathology Journal
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• v.20 no.3
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• pp.229-233
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• 2004

The bacterial leaf blight, which is caused by Xantho-monas oryzae pv. oryzae, is the most damaging and intractable disease of rice. To identify the genes involved in the virulence mechanism of transposon TnS complex, which possesses a linearized transposon and transposase, was successfully introduced into X. oryzae pv. oryzae by electroporation. The transposon mutants were selected and confirm the presence of transposition in X. oryzae pv. oryzae by the PCR amplification of transposon fragments and the Southern hybridization using these mutants. Furthermore, transposon insertion sites in the mutant bacterial chromosome were deter-mined by direct genomic DNA sequencing using transposon-specific primers with ABI 3100 Genetic Analyzer. Efficiency of transposition was influenced mostly by the competence status of X. oryzae pv. oryzae cells and the conditions of electroporation. These results indicated that the insertion mutagenesis strategy could be applied to define function of uncharacterized genes in X. oryzae pv. oryzae.

• Korean Journal Plant Pathology
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• v.1 no.1
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• pp.61-66
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• 1985

Seventy-one strains collected from Korea were classified into three serovars (designated A, B-I and B-II) by using agar gel diffusion test with the antisera produced against Xanthomonas campestris pv. oryzae isolates Q7472 and Q7502. Of 71 isolates tested, 65 isolates belonged to serovar A, 5 isolates were serovar B-I, and one isolate was serovar B-II. The isolates of serovar B-I and B-II could be distinguished clearly from those of serovar A showing marked autoagglutination. Xanthomonas campestris pv. oryzae was serologically diagnosed in rice leaves by agar gel diffusion tests, possibly being distinguished from Xanthomonas campestris pv. olyzicola and E. herbicola. The pathogen could be also serologically detected from the extracts of diseased leaves, squeezed immediately, heated at $100^{\circ}C$ or incubated in PSA. Serological detection of Xanthomonas campestris pv. oryzae is a more reliable and less time-comsuming method.

• Journal of Microbiology and Biotechnology
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• v.23 no.9
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• pp.1287-1292
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• 2013

Extracellular biogenic synthesis of silver nanoparticles with various shapes using the rice bacterial blight bacterium Xanthomonas oryzae pv. oryzae BXO8 is reported. The synthesized silver nanoparticles were characterized by UV-Vis spectroscopy, powder X-ray diffractometry (XRD), scanning electron microscopy, energy dispersive X-ray spectrometry, and high-resolution transmission electron microscopy (HR-TEM). Based on the evidence of HR-TEM, the synthesized particles were found to be spherical, with anisotropic structures such as triangles and rods, with an average size of 14.86 nm. The crystalline nature of silver nanoparticles was evident from the bright circular spots in the SAED pattern, clear lattice fringes in the high-resolution TEM images, and peaks in the XRD pattern. The FTIR spectrum showed that biomolecules containing amide and carboxylate groups are involved in the reduction and stabilization of the silver nanoparticles. Using such a biological method for the synthesis of silver nanoparticles is a simple, viable, cost-effective, and environmentally friendly process, which can be used in antimicrobial therapy.

• Plant Resources
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• v.7 no.1
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• pp.65-68
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• 2004

We used an amplified fragment length polymorphism (AFLP) analysis, a novel PCR-based technique, to differentiate Xanthomonas oryzae pv. oryzae (Xoo) of Korean races. The 6 strains of Xoo K1, K2, K3 races were tested with 81 AFLP primer combinations to identify the best selective primers. The primer combinations were selected according to their reproducibility, number of polymorphic bands and polymorphism detected among Xoo strains. 18 strains of Xoo K1, K2 and K3 races were analyzed with the selected combinations of primer set. Some primer combinations (Eco R I +1 / Mse I+1) could differentiate Xoo of Korean races that were not distinguished by other fingerprinting analysis. Thus AFLP fingerprinting permitted very fine discrimination among different races.