• Microbiology and Biotechnology Letters
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• v.19 no.1
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• pp.14-20
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• 1991

- The purpose of this work is to investigate the effects of various substrates on biosynthesis of ethylene by the Kudzu strain of Pseudomonas syn'ngae pv. Phaseolicola causing halo blight. In the intact cell of P. sym'ngue, optimal condition for ethylene production was achieved at p1-I 7.5 and $30^{\circ}C$ for 9 to 10 hours of culture. Ethylene was most effectively produced from amino acids such as Asn, Gln, Asp ans Glu, compared to those of various kinds of sugars. While ethylene production from $\alpha$-ketoglutarate ($\alpha$-KG) was gradually increased throughout 51 hours incubation period tested. Ethylene production derived from citrate, $\alpha$-KG and oxalacetate as well as a few amino acids was further enhanced by the addition of histidine or arginine. In cell-free ethylene-forming system, ethylene was most effectively produced from $\alpha$-KG, compared to those from citrate, oxalacetate, Glu, Arg, or Asp, at 0.5 mM among the range from 0.25 mM to 5 mM. Anlinooxyacetate, an inhibitor of a pyridoxal phosphate-linked enzyme, completely inhibited ethylene evolution derived from Glu but not affect that derived from $\alpha$-KG. The results obtained in this work suggest that $\alpha$-KG might be a direct precursor of ethylene production in this organism than any other substrates tested.

• The Korean Journal of Pesticide Science
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• v.10 no.3
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• pp.230-236
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• 2006

Eighty-five percent methanol extract of Agrimonia pilosa has antibacterial activity against Pseudomonas syringae pv. lacrymans (bacterial leaf spot pathogen), Ralstonia solanacearum (tomato bacterial wilt pathogen) and Pseudomonas syringae pv. tabaci (Tobacco wild fire pathogen.). The active substance was purified by silica gel column chromatography and HPLC. The molecular weight of the active compound was determined by LC-Mass as 687.2. With NMR analysis, the active substance was identified as Agrimol B.

• BMB Reports
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• v.38 no.6
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• pp.748-754
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• 2005

Pseudomonas syringae pv. tomato (Pst) causes a bacterial speck disease in tomato and Arabidopsis. In Chinese cabbage, in which host-pathogen interactions are not well understood, Pst does not cause disease but rather elicits a hypersensitive response. Pst induces localized cell death and $H_2O_2$ accumulation, a typical hypersensitive response, in infiltrated cabbage leaves. Pre-inoculation with Pst was found to induce resistance to Erwinia carotovora subsp. carotovora, a pathogen that causes soft rot disease in Chinese cabbage. An examination of the expression profiles of 12 previously identified Pst-inducible genes revealed that the majority of these genes were activated by salicylic acid or BTH; however, expressions of the genes encoding PR4 and a class IV chitinase were induced by ethephon, an ethylene-releasing compound, but not by salicylic acid, BTH, or methyl jasmonate. This implies that Pst activates both salicylate-dependent and salicylate-independent defense responses in Chinese cabbage.

• The Plant Pathology Journal
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• v.32 no.2
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• pp.162-167
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• 2016

Pseudomonas syringae pv. actinidiae, the causal agent of canker in kiwifruit, can be divided into three biovars (biovars 1, 2, and 3). Strains belonging to biovar 1 produce phaseolotoxin and were isolated in Japan and Italy before 2008. Strains of biovar 2 produce coronatine instead of phaseolotoxin and have been isolated only in Korea. Strains belonging to biovar 3 produce neither phaseolotoxin nor coronatine and are responsible for the global outbreak of bacterial canker of kiwifruit in recent years. The biovar 3-specific primer set was developed in a previous work. In this study, two sets of PCR primers specific to strains of biovars 1 and 2, respectively, were developed based on random amplified polymorphic DNA analyses. Primers PsaJ-F and PsaJ-R produced a 481-bp region with genomic DNA of biovar 1 strains, whereas primers PsaK-F and PsaK-R amplified a 413-bp region present only in the genome of biovar 2 strains.

• The Plant Pathology Journal
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• v.32 no.4
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• pp.363-370
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• 2016

Pseudomonas syringae pv. actinidiae (Psa) causes bacterial canker disease in kiwifruit. Antibacterial activity of plant essential oils (PEOs) originating from 49 plant species were tested against Psa by a vapor diffusion and a liquid culture assays. The five PEOs from Pimenta racemosa, P. dioica, Melaleuca linariifolia, M. cajuputii, and Cinnamomum cassia efficiently inhibited Psa growth by either assays. Among their major components, estragole, eugenol, and methyl eugenol showed significant antibacterial activity by only the liquid culture assay, while cinnamaldehyde exhibited antibacterial activity by both assays. The minimum inhibitory concentrations (MICs) of estragole and cinnamaldehyde by the liquid culture assay were 1,250 and 2,500 ppm, respectively. The MIC of cinnamaldehyde by the vapor diffusion assay was 5,000 ppm. Based on the formation of clear zones or the decrease of optical density caused by these compounds, they might kill the bacterial cells and this feature might be useful for managing the bacterial canker disease in kiwifruit.

• The Plant Pathology Journal
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• v.36 no.6
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• pp.608-617
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• 2020

The type III secretion system (T3SS) is a key virulence determinant in the infection process of Pseudomonas syringae pv. tomato DC3000 (Pst DC3000). Pathogen constructs a type III apparatus to translocate effector proteins into host cells, which have various roles in pathogenesis. 4-Hydroxybenozic acid and vanillic acid were identified from root extract of Sedum middendorffianum to have inhibitory effect on promoter activity of hrpA gene encoding the structural protein of the T3SS apparatus. The phenolic acids at 2.5 mM significantly suppressed the expression of hopP1, hrpA, and hrpL in the hrp/hrc gene cluster without growth retardation of Pst DC3000. Auto-agglutination of Pst DC3000 cells, which is induced by T3SS, was impaired by the treatment of 4-hydroxybenzoic acid and vanillic acid. Additionally, 2.5 mM of each two phenolic acids attenuated disease symptoms including chlorosis surrounding bacterial specks on tomato leaves. Our results suggest that 4-hydroxybenzoic acid and vanillic acid are potential anti-virulence agents suppressing T3SS of Pst DC3000 for the control of bacterial diseases.

• Journal of Life Science
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• v.30 no.1
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• pp.1-9
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• 2020

Pseudomonas syringae pv. actinidiae, the causal agent of a bacterial canker disease in kiwifruit, is subdivided into five genetically distinct populations, namely biovars 1, 2, 3, 5, and 6. Of these, strains belonging to biovar 3 are responsible for a pandemic bacterial canker of kiwifruits since 2008. This study aimed to characterize the structure of the biovar 3 population and investigate the origin of biovar 3 strains isolated in Korea. The genetic variability of fifteen biovar 3 strains, thirteen Korean and two Chinese, were evaluated through random amplified polymorphic DNA (RAPD)-PCR. The RAPD results revealed the presence of eight lineages, designated as subgroups I-VIII, across the biovar 3 strains used in this study. As the strains in subgroups II and III from China were not found in the Korean examples, we concluded that six genetically different biovar 3 subgroups (I, IV, V, VI, VII, and VIII) are present in Korea. In PCR analysis using primers specific to the strains of New Zealand and Europe, Korean strains in subgroups V and VI amplified the relevant DNA bands, suggesting that these were introduced from these two origins, respectively. PCR primers specific to subgroup VIII were developed to monitor the spread of the first biovar 3 strain in Korea, and investigations revealed that this strain was not found in Korea after its first occurrence.

• Journal of Life Science
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• v.31 no.1
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• pp.52-58
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• 2021

Pseudomonas syringae pv. actinidiae, which causes bacterial canker in kiwifruit, is divided into five biovars (1, 2, 3, 5, 6) on the basis of genetic characteristics and toxin productivity. Among them, biovar 3 is responsible for the current global outbreak, and has been isolated in Korea since 2011. Biovar 3 strains isolated from Korea are subdivided into six genetically different lineages (subgroup I, IV, V, VI, VII, and VIII) based on random amplified polymorphic DNA (RAPD) analysis. In this work, the subgroup-specific sequence characterized amplified region (SCAR) primers were developed from sequenced differential RAPD bands. Distribution of the subgroups of the biovar 3 strains collected in Korea from 2011-2017 were examined using these subgroup-specific primer sets. Among the 54 strains tested, 35 strains (64.8%) belonged to subgroup V, 9 strains (16.7%) belonged to subgroup IV, 4 strains (7.4%) belonged to subgroup VI, 3 strains (5.6%) belonged to subgroup VII, 2 strains (3.7%) belonged to subgroup VIII, and 1 (1.9%) strain belonged to subgroup I. Strains belonging to subgroups IV, V, and VI were shown to be related to strains isolated from China, New Zealand, and Chile, respectively. The study revealed that the biovar 3 strains in Korea are genetically diverse and are estimated to have been introduced through pollen sourced from foreign countries.

• Journal of Microbiology and Biotechnology
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• v.26 no.2
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• pp.385-393
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• 2016

Pseudomonas syringae pv. actinidiae causes bacterial canker disease in kiwifruit. Owing to the prohibition of agricultural antibiotic use in major kiwifruit-cultivating countries, alternative methods need to be developed to manage this disease. Bacteriophages are viruses that specifically infect target bacteria and have recently been reconsidered as potential biological control agents for bacterial pathogens owing to their specificity in terms of host range. In this study, we isolated bacteriophages against P. syringae pv. actinidiae from soils collected from kiwifruit orchards in Korea and selected seven bacteriophages for further characterization based on restriction enzyme digestion patterns of genomic DNA. Among the studied bacteriophages, two belong to the Myoviridae family and three belong to the Podoviridae family, based on morphology observed by transmission electron microscopy. The host range of the selected bacteriophages was confirmed using 18 strains of P. syringae pv. actinidiae, including the Psa2 and Psa3 groups, and some were also effective against other P. syringae pathovars. Lytic activity of the selected bacteriophages was sustained in vitro until 80 h, and their activity remained stable up to 50℃, at pH 11, and under UV-B light. These results indicate that the isolated bacteriophages are specific to P. syringae species and are resistant to various environmental factors, implying their potential use in control of bacterial canker disease in kiwifruits.

• Research in Plant Disease
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• v.21 no.2
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• pp.67-73
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• 2015

Bacterial blossom blight of kiwifruit (Actinidia deliciosa) caused by Pseudomonas syringae pv. syringae is known to be largely affected by weather conditions during the blooming period. While there have been many studies that investigated scientific relations between weather conditions and the epidemics of bacterial blossom blight of kiwifruit, no forecasting models have been developed thus far. In this study, we collected all the relevant information on the epidemiology of the blossom blight in relation to weather variables, and developed the Pss-KBB Risk Model that is based on the Maryblyt model for the fire blight of apple and pear. Subsequent model validation was conducted using 10 years of ground truth data from kiwifruit orchards in Haenam, Korea. As a result, it was shown that the Pss-KBB Risk Model resulted in better performance in estimating the disease severity compared with other two simple models using either temperature or precipitation information only. Overall, we concluded that by utilizing the Pss-KBB Risk Model and weather forecast information, potential infection risk of the bacterial blossom blight of kiwifruit can be accurately predicted, which will eventually lead kiwifruit growers to utilize the best practices related to spraying chemicals at the most effective time.