• The Plant Pathology Journal
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• v.17 no.6
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• pp.336-341
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• 2001

The distribution of citrusphages and phage types of Xanthomonas axonopodis pv. citri was investigated in Korea. Forty-eight strains of the bacterial pathogen and 28 bacteriophage strains were isolated from citrus leaves showing the citrus canker symptom. Only a single bacteriophage group, named CPK, was identified based on their aggressiveness to the bacterial pathogen. The bacterial strains were differentiated into two Iysotypes based on their sensitivity to CPK. Lysotype I, which was sensitive to CPK, was more predominant (96%), while only 4% belonged to Iysotype II, which was resistant to CPK. Among the 13 xanthomonads including Iysotype A and Iysotype B of X axonopodis pv. citri, CPKs were only aggressive to BC 83 (=Xc 62) strain of X. axonopodis pv, citri reported as Iysotype A. Thus, bacterial pathogens and citrusphages related to citrus plants mainly distributed in Korea were presumed as Iysotype A of X. axonopodis pv, citri, and Iysotype A-infecting CP$_1$ respectively.

• The Plant Pathology Journal
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• v.22 no.4
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• pp.314-317
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• 2006

A phage technique for detection of Xanthomonas axonopodis pv. citri, a causal bacterium of canker on Sastuma mandarin fruits was developed. Phage and ELISA techniques were compared for their sensitivity for detection of Xanthomonas axonopodis pv. citri on orange fruits. Both of techniques revealed a similar efficiency for the bacterial detection; the pathogenic bacteria were observed in pellet from the fruits with over one canker spot with below 2 mm in diameter. In field assays, the increase of phage population(120%) on surface of the fruits related to the disease development one month later indicated that the bacterial pathogens inhabit on the surface. The procedure will be effectively used for detection of only living bacterial pathogen on fruit surfaces of Satsuma mandarin and for the disease forecasting.

• The Plant Pathology Journal
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• v.19 no.4
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• pp.205-209
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• 2003

Dispersal of citrus bacterial canker caused by Xanthomonas axonopodis pv. citri on Unshiu orange was investigated in naturally infested nursery plot at Seogwipo in Jeju island, Korea. Based on phage detection, over 2% of the bacterial pathogen over-wintered in canker lesions and started to multiply in late May. However, symptoms were first observed 1 month after the phage detection. The disease dispersed non-directionally to nearby plants possibly because of indirect dissemination of the bacterium by rain splashes. The disease increased from late June to late August and decreased thereafter. Population of phage increased constantly, however, disease occurrence somewhat fluctuated due to environmental factors. Disease incidence and severity were correlated with rainfall with wind that occurred 14-32 days earlier from late May to late August.

• The Plant Pathology Journal
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• v.24 no.4
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• pp.423-432
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• 2008

The difference of carbon source utilization and fatty acid composition between the pathotypes of Xanthomonas strains, which causing citrus bacterial canker was compared, and the physiochemical characteristics were used to analyze relationship of the strains for the first time. The pattern of several carbon sources utilization and fatty acids composition reliably discriminated the pathotypes of Xanthomonas strains. The dendrogram which was constructed by 95 carbon source utilization profiles differentiated X. axonopodis pv. citri A, $A^*$ and $A^w$ from the other pathotypes. When the dendrogram was drawn by combined analysis of carbon source utilization pattern and fatty acid composition, X. axonopodis pv. aurantifolii B, C and X. axonopodis pv. citrumelo formed a distinct cluster. The difference of carbon source utilization and fatty acid composition could be used effectively for the identification of pathotypes of citrus bacterial canker. The physiochemical characteristics strongly indicated that the strains isolated in Korea belong to X. axonopodis pv. citri A type. The cluster analysis by the band patterns of ERIC-, BOX- and REP-PCR allowed the discrimination of the pathotypes isolated from Korea. However, the rep-PCRs could not differentiate X. axonopodis pv. citri A types from $A^*$ and $A^w$ types. The overall results of metabolic profiles and rep-PCRs strongly indicated that the Korean isolates are X. axonopodis pv. citri A type.

• Research in Plant Disease
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• v.10 no.2
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• pp.94-99
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• 2004

'Shiranuhi' citrus cultivar bred by crossing 'Kiyomi' tangor and 'Nakano No.3' ponkan is cultivated in polyethylene film house, and the number of cultivating farmers is rapidly increasing in recent years. Recently, some diseases are taking place on 'Shiranuhi' fruit in some orchards, and were to be big problem in some case. It was surveyed that six diseases were mainly taken place in 'Shiranuhi' cultivating orchards in Jeju Island. They were Phytophthora citrophthora, Alternaria sp., Penicillium digitatum, Botrytis cinerea, Diaporthe citri and Xanthomonas axonopodis pv. citri.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.135.1-135
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• 2003

A technique for detection of Xanthomonas axonopodis pv. citri, a causal bacterium of canker on Unshiu orange fruits, was developed using bacteriophage. Procedure for the detection was designed on the basis of the previous reports that one group(CPI) of X. axonopodis pv. citri bacteriophage and corresponding two Iysotypes distributed in Korea. First, fruit surface was washed with sterile distilled water and pellet was obtained from centrifugation. The pellet was resuspended in Wakimoto's potato semi-synthetic broth medium and divided equally into two parts. One part was heated in boiling water to kill bacterial cells. Bacteriophages(CP$_1$) were respectively added into two parts and 0.1 ml from each part was mixed with soft agar medium. After incubation for 18 hrs at 25$^{\circ}C$, the causal bacterium of canker was determined based on plaques formed on the medium. This procedure can be effectively used for detection of living bacterial pathogen on fruit surfaces of Unshiu orange.

• The Plant Pathology Journal
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• v.18 no.6
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• pp.333-337
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• 2002

Bacteriophage of Xanthomonas axonopodis pv. citri, a causal agent of citrus canker disease, was studied for its cultural characteristics. The relative efficiency of plat-ing (EOP) of 11 phages used to 13 strains off, axonopodis pv. citri tested ranged from 0.8 to 1, indicating that the phages are homogeneous. Homogeneity of the phages suggests that citrusphage belongs to a single group CPK as reported in a previous study. Typical one-step growth of a phage P5 selected from the citrusphages was observed. The EOP of the P5 was dependent upon the media, pH, and temperature. It was observed that multiplication of the phage cultured in Wakimotos potato semisynthetic media at $25^{\circ}C$ was more effective than that in other temperatures, regardless of the bacterial strains and media used. It was observed that pH 6.5 is optimal for multiplication of the phage. In comparison of the EOP among citrusphages $CP_1$, $CP_2$, and P5, multiplicative characteristic of phage P5 in the bacteria on time-course was similar with that of phage $CP_1$. Thus, it was concluded that citrusphage group CPK from Korea is $CP_1$ based on host specificity of the phage as described in a previous study, homogeneity, and its multiplication pattern.

• Research in Plant Disease
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• v.18 no.2
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• pp.129-132
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• 2012

Citrus bacterial canker is an economically important disease affecting citrus production in many citrusgrowing areas and several pathotypes have been recognized within the Xanthomonas pathogens causing canker. In view of the containment of the disease, accurate identification of the causal bacterium is important. In this study, triplex PCR method was developed by using the previously reported primers. Two groups of primer combination, such as, one group including primers 2/3, J-pth1/J-pth2 and XACF/XACR, and another group 2/3, J-pth1/J-pth2 and Xac01/Xac02, were suitable for the detection and differentiation of X. a. pv. citri $A^w$, X. a. pv. aurantifolii B and C, and X. a. pv. citrumelo E strains. Moreover, the primer combination of Xac01 and J-pth2 promised us to use as a specific primer set to detect X. a. pv. citrumelo E strain. The PCR methods developed in this study could be used for the rapid differentiation of Xanthomonas pathotypes of citrus.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 1999.10a
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• pp.64.1-64
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• 1999

• 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.