• Research in Plant Disease
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• v.28 no.4
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• pp.209-220
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• 2022

Charcoal canker of oak, which has recently increased in southern Iran, could pose a serious threat to the entire forest ecosystem in the near future. In addition, it seems that climate change and its consequences, such as drought in the southern regions of Iran, have exacerbated this phenomenon. Consequently, the objective of this study was to identify the fungal pathogens that could cause charcoal canker disease in the oak forests of South Zagros. It was also sought to find associations between changes in the occurrence/exacerbation of charcoal canker disease under non and intense drought stress in non-inoculated or inoculated Quercus brantii seedlings. In total, 120 isolates were obtained from eight oak forests located in the Zagros Mountains of Southern Iran, Kohgiluyeh & Boyer-Ahmad and Fars provinces, which were classified as Biscogniauxia mediterranea based on morphological assessment. Subsequently, molecular assay confirmed the result by phylogenetic inference of internal transcribed spacer-rDNA regions, α-actin, and β-tubulin genes. The results of the pathogenicity test showed that the response of isolates of B. mediterranea (Iran-G1 and Iran-M70) was varied in different environments for the measured necrotic lesion length. In comparison with the control moisture treatments (non-stress), the necrotic lesion length in inoculated treatments increased under intense drought stress. In general, inoculated oak seedlings' exposure to water-deficient stress by the pathogen of B. mediterranea could affect the spread/severity of the charcoal canker disease.

• The Plant Pathology Journal
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• v.39 no.1
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• pp.88-107
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• 2023

In the present investigation, bacterial isolates from infected apple trees causing apple canker during winter were studied in the northern Gyeongbuk Province, Korea. The pathogen was identified as Pseudomonas syringae pv. syringae (Pss) through various physiological and biochemical characterization assays such as BIOLOG, gas chromatography of fatty acid methyl esters, and 16S rRNA. Bioassays for the production of phytotoxins were positive for syringopeptin and syringomycin against Bacillus megaterium and Geotrichum candidum, respectively. The polymerase chain reaction (PCR) method enabled the detection of toxin-producing genes, syrB1, and sypB in Pss. The differentiation of strains was performed using LOPAT and GATTa tests. Pss further exhibited ice nucleation activity (INA) at a temperature of -0.7℃, indicating an INA⁺ bacterium. The ice-nucleating temperature was -4.7℃ for a non-treated control (sterilized distilled water), whereas it was -9.6℃ for an INA^- bacterium Escherichia coli TOP10. These methods detected pathogenic strains from apple orchards. Pss might exist in an apple tree during ice injury, and it secretes a toxin that makes leaves yellow and cause canker symptoms. Until now, Korea has not developed antibiotics targeting Pss. Therefore, it is necessary to develop effective disease control to combat Pss in apple orchards. Pathogenicity test on apple leaves and stems showed canker symptoms. The pathogenic bacterium was re-isolated from symptomatic plant tissue and confirmed as original isolates by 16S rRNA. Repetitive element sequence-based PCR and enterobacterial repetitive intergenic consensus PCR primers revealed different genetic profiles within P. syringae pathovars. High antibiotic susceptibility results showed the misreading of mRNA caused by streptomycin and oxytetracycline.

• 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.

• Journal of Microbiology and Biotechnology
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• v.28 no.9
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• pp.1542-1546
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• 2018

Bacterial canker in kiwifruit is caused by Pseudomonas syringae pv. actinidiae (Psa). In this study, the bacteriophage PPPL-1 effective against Psa was characterized. Belonging to the Podoviridae family, PPPL-1 was effective against most Psa strains as well as most Pseudomonas syringae pathovars. PPPL-1 carries a 41,149-bp genome with 49 protein coding sequences and is homologous to the previously reported phiPSA2 bacteriophage. The lytic activity of PPPL-1 was stable up to $40^{\circ}C$, within a range of pH 3-11 and under 365 nm UV light. These results indicate that the bacteriophage PPPL-1 might be useful to control Psa in the kiwifruit field.

• Mycobiology
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• v.30 no.4
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• pp.240-243
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• 2002

Embellisia allii causing bulb canker of white garlic(Allium sativum) has been observed on harvested or stored garlic bulbs. Identification of the fungus was determined based on the symptoms and morphological characteristics on in vitro potato dextrose agar(PDA) and malt extract agar(MEA). Colonies were effuse, blackish brown to black, velvety or powdery. Conidia were solitary, almost straight, most commonly ellipsoidal(or subcylindrical) to ovoid, mid to dark brown, smooth, with very dark 1 to 6 transverse(commonly $3{\sim}4$) and occasionally 1 or 2 oblique or longitudinal septa, and $30.4{\times}13.4{\mu}m$(av.). Conidiophores were simple or branched, straight or flexuous, up to 80 ${\mu}m$ long and $5.1{\sim}10.2{\mu}m$ thick. Chlamydospores were developed through enlargement and repeated cellular division of several adjacent hyphal cells to form a complex of thickwalled cells. The conidial measurements of garlic isolates closely matched the previous description of E. allii.

• The Plant Pathology Journal
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• v.16 no.1
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• pp.52-54
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• 2000

Pitch canker of Pinus rigida, caused by Fusarium subglutinans f. sp. pini, was first noticed in Inchon, Korea, and is now being spread into other plantations of pines. Typical symptoms re resin flows from canders on the shoots, branches, and trunks, and resin-soaking of the sap wood under the bark. Pathogenic fungi were isolated from the infected shoots, branches, and sees on Fusarium-selective medium. Mycelial growth and microscopic characteristics were examined. Pathogenicity test was carried out by inoculating four common species of pines (P. rigida, P. densiflora, P. thunbergii, and P. koraiensis) in Korea. P. rigida and P. thunbergii showed symptoms identical to those of naturally infected trees, while P. densiflora and P. koraiensis remained free symptomless.

• Korean Journal Plant Pathology
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• v.13 no.2
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• pp.125-128
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• 1997

Reactions of Pseudomonas syringae pv. actinidiae to 95 carbon sources in a 96-well microplate (BiOLOG GN MicroPlateTM) were investigated. The bacterium used 9 carbon sources such as D-mannitol, sucrose, etc., but did not use 62 carbon sources such as $\alpha$-cyclodextrin, dextrin, etc. Based on the reactions, a user data base for identification of P. syringae pv. actinidiae was constructed in Biolog program (BiOLOG MicroLogTM 2 system). P. syringae pv. actinidiae isolates collected from kiwifruits could be identified automatically with high similarity using the user data base, which could diagnose rapidly and easily whether the tree was infected with bacterial canker or not.

• Mycobiology
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• v.43 no.3
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• pp.366-370
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• 2015

Acanthopanax divaricatus, a member of the Araliaceae family, has been used as an invigorant in traditional Korean medicine. During disease monitoring, a stem with small, irregular, brown lesions was sampled at a farm in Cheonan in 2011. The symptoms seen were sunken cankers and reddish-brown needles on the infected twig. The isolated fungal colonies were whitish, having crenated edges and aerial mycelium on the surface, and with black gregarious fruiting bodies. The reverse plate was creamy white. Conidia were $17{\sim}22{\times}3.5{\sim}4.2{\mu}m$, fusiform, 4-septate, and straight to slightly curved. The nucleotide sequence of the partial translation elongation factor 1 alpha gene of the fungal isolate, shares 99% sequence identity with that of known Pestalotiopsis ellipsospora. Based on the results of the morphological and molecular analyses, the fungal isolate was identified as P. ellipsospora. In Korea, this is the first report of canker on A. divaricatus.

• The Plant Pathology Journal
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• v.37 no.5
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• pp.489-493
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• 2021

Bacterial canker is a devastating disease of kiwifruit caused by the bacterium Pseudomonas syringe pv. actinidiae. Canker disease of kiwifruit in Korea has been controlled using streptomycin for more than two decades. Four streptomycin-resistant strains, belonging to biovar 2, which are found only in Korea, were collected between 2013 and 2014 from different orchards located in Jeju, Korea. The genetic background for streptomycin resistance among P. syringe pv. actinidiae strains were determined by examining the presence of strA-strB or aadA, which are genes frequently found in streptomycin-resistant bacteria, and a point mutation at codon 43 in the rpsL gene. All four streptomycin-resistant strains of P. syringe pv. actinidiae investigated in this study contained strA-strB as a resistant determinant. The presence of the aadA gene and a mutation in codon 43 of the rpsL gene was not identified.

• Korean journal of applied entomology
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• v.9 no.2
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• pp.81-84
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• 1970

The occurence of apple canker in the three main apple growing areas including Yesan, Chungju and Taegu was investigated during the four years from 1967 to 1970. According to the survey, about 30 percent of apple plants was infected with canker organisms and more the disease occurred in older plants in comparison with younger ones. Jonathan was said to be highly susceptible among five varieties observed. Main trunks or main branches had more canker lesions than those of twigs or of side branches. The survey showed that application of higher nitrogenous fertilizer without boric acid predisposed to the disease together with sandy soil.