• 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.

• Research in Plant Disease
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• v.22 no.4
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• pp.276-283
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• 2016

Bacterial canker caused by Pseudomonas syringae pv. actinidiae (Psa) occurred at 202 kiwifruit orchards for the survey period of 2013-2016, of which Psa biovar 2 (Psa2) and Psa biovar 3 (Psa3) were detected at 73 and 129 kiwifruit orchards, respectively. The number of kiwifruit orchards infected by Psa3 in 2016 increased nearly two times compared to 2015. Psa3 was detected from all the kiwifruit cultivars except some kiwiberry cultivars growing in Korea. Yellow-fleshed cultivars Hort16A and Jecy-gold and red-fleshed cultivar Hongyang were highly susceptible to Psa3. Our epidemiological and random amplification of polymorphic DNA analyses indicated that the first Psa3 incidence on Hongyang orchard in Sacheon, Gyoungnam might result from an introduction of Psa3-contaminated pollens from China for artificial pollination in 2014 and recent outbreaks of Psa3 in Sacheon and Goseong, Gyoungnam in 2016 might be due to rapid spread of bacterial canker by secondary infection of Psa3 from Hongyang orchard to neighboring Jecy-gold and Hayward orchards.

• The Plant Pathology Journal
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• v.28 no.4
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• pp.423-427
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• 2012

Pseudomonas syringae pv. actinidiae strains, the causal agents of bacterial canker on kiwifruit, were isolated from Korea and Italy in 2011. Among 87 isolates, a total of six representative strains, three from Korea and three from Italy, were identified on the basis of biochemical and physiological tests. Identities were confirmed by PCR using P. syringae pv. actinidiae-specific primers PsaF1/R2, which amplified a 280-bp DNA fragment. The strains isolated from Korea in this study displayed BOX-PCR patterns similar to those isolated from Italy but different from those isolated previously in Korea or the pathotype P. syringae pv. actinidiae strain. The effector hopA1 and hopH1 genes, which are known to be present in strains isolated recently from France and Italy, were also present in P. syringae pv. actinidiae strains, SYS1, SYS2 and SYS4, isolated from Korea in this work. However, no amplicons of the expected size were obtained from strains previously isolated from Korea and Japan. In addition, the Korean strains isolated in this work belonged to haplotype I for the cts gene identical to those strains isolated from recent outbreaks in Italy. These results suggest that P. syringae pv. actinidiae strains isolated from Korea and examined in this work are a new type of strain similar to those found from recent outbreaks in Italy. This is the first report on the occurrence of cts haplotype I strains of P. syringae pv. actinidiae affecting kiwifruit plants in Korea.

• The Plant Pathology Journal
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• v.33 no.6
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• pp.554-560
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• 2017

After 20 years of steady increase, kiwifruit industry faced a severe arrest due to the pandemic spread of the bacterial canker, caused by Pseudomonas syringae pv. actinidiae (Psa). The bacterium penetrates the host plant primarily via natural openings or wounds, and its spread is mainly mediated by atmospheric events and cultural activities. Since the role of sucking insects as vectors of bacterial pathogens is widely documented, we investigated the ability of Metcalfa pruinosa Say (1830), one of the most common kiwifruit pests, to transmit Psa to healthy plants in laboratory conditions. Psa could be isolated both from insects feeding over experimentally inoculated plants, and from insects captured in Psa-infected orchards. Furthermore, insects were able to transmit Psa from experimentally inoculated plants to healthy ones. In conclusion, the control of M. pruinosa is recommended in the framework of protection strategies against Psa.

• Korean Journal Plant Pathology
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• v.12 no.3
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• pp.324-330
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• 1996

암수 딴그루인 참다래 품종 중에서 우리나라에서 재배되고 있는 대표적인 결실수(암나무)인 Hayward와 수분수(숫나무)인 Matua에서 궤양병의 발생 차이를 조사한 결과 Hayward의 이병엽율은 18.0%인 반면에 Matua의 이병엽율은 2.4%였다. 또한 Hayward와 Matua의 잎에 형성된 병반에서 분리된 궤양병균의 균총수는 생체중 1 g당 각각 1.8$\times$10\ulcorner개와 2.1$\times$10\ulcorner개로 Hayward에서 Matua보다 약 10배 가량 많은 궤양병균이 검출되었다. Hayward 신초에 존재하는 궤양병균의 밀도를 조사한 결과 줄기 조직보다는 잎 조직에서 많은 궤양병균이 검출되었으며 새로 나온 잎일수록 궤양병균의 밀도는 낮게 검출되었다. 궤양병 방제를 위하여 스트렙토마이신 수간주입에 의한 궤양병 치료효과는 50.7~53.7%였다. 수간주입시 약량을 주당 2 L에서 3 L와 4 L로 증가시킴에 따라 치료효과도 32.3%에서 58.1%와 71.0%로 각각 증대되었는데, 수간주입 약제와 수간주입 방법의 개선을 통하여 궤양병 치료효과를 더욱 증대시킬 수 있을 것으로 기대된다.

• Research in Plant Disease
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• v.24 no.1
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• pp.1-8
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• 2018

Bacterial diseases such as bacterial canker and bacterial leaf spot and fungal diseases such as gray mold, powdery mildew, side rot and leaf spots are major diseases damaging leaves of kiwifruit in Korea. In this review, we summarize symptoms and epidemiological characteristics of the major bacterial and fungal leaf diseases of kiwifruit and propose proper control methods of the diseases that can be practically utilized at the farmers' kiwifruit orchards in order to prevent the diseases on the basis of our research works and field experiences and important research products conducted during the last three decades in the world.

• Research in Plant Disease
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• v.11 no.1
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• pp.80-84
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• 2005

Bacterial canker of sweet cherry (Prunus avium L.) was observed in farmers\' orchards in Goesan, Chungbuk in 2003. Typical canker symptoms occurred on the branches or twigs of sweet cherry in early spring and bacterial exudates oozed out of the cracked barks of diseased trees. Watersoaked brown symptoms appeared on the leaves and severe infection caused thorough defoliation on the branches or twigs of sweet cherry. When severely infected branches or twigs were cut, irregular and rusty-colored symptoms in sapwood and heartwood were clearly found, indicating that they can serve as specific symptoms of bacterial canker of sweet cherry. The causal bacterium responsible for the symptoms was isolated purely from the infected sapwood of sweet cherry. Based on its morphological, physiological and biochemical characteristics, the causal bacterium was identified as Pseudomonas syringae pv. morsprunorum. The bacterium was pathogenic on sweet cherry and Japanese apricot, but not on peach, cherry, and kiwifruit. It is proposed that the disease be named as bacterial canker of sweet cherry.

• The Plant Pathology Journal
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• v.34 no.2
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• pp.143-149
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• 2018

Flowers of kiwifruit are morphologically hermaphroditic and survivable binucleate pollen is produced by the male flowers. In this study, we investigated microbial diversity in kiwifruit pollens by analyzing amplicon sequences of 16S rRNA. Four pollen samples were collected: 'NZ' was imported from New Zealand, 'CN' from China in year of 2014, respectively. 'KR13' and 'KR14' were collected in 2013' and 2014' in South Korea. Most of the identified bacterial phyla in the four different pollens were Proteobacteria, Actinobacteria and Firmicutes. However, the imported and the domestic pollen samples showed different aspects of microbial community structures. The domestic pollens had more diverse in diversity than the imported samples. Among top 20 OTUs, Pseudomonas spp. was the most dominant specie. Interestingly, a bacterial pathogen of kiwifruit canker, Pseudomonas syringae pv. actinidiae was detected in 'NZ' by the specific PCR. This study provides insights microbial distribution and community structure information in kiwifruit pollen.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2000.10a
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• pp.47.1-47
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• 2000

• Research in Plant Disease
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• v.10 no.4
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• pp.310-312
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• 2004

Pseudomonas syringae pv. actinidiae is the causative agent of bacterial canker in kiwifruit. A nested PCR detection method that uses primers designed from the cfl gene, involved in production of the phytotoxin coronatine, was applied on soil samples. These primers yielded 665 and 310-bp fragments in consecutive PCR amplification step with DNA from soil inoculated with Korean strain of P. syringae pv. actinidiae. This system was applied to survey soil samples from a kiwifruit orchard destroyed by bacterial canker. A specific 310-bp PCR product was obtained from all six samples of soil tested.