• Research in Plant Disease
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• v.9 no.1
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• pp.32-35
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• 2003

Pink rot of potato (Solanum tuberosum L.) occurred at Pyeongchang in Gangwon and at Bosung in Junnam province since 1999. The disease incidence in the surveyed areas was about 5% of harvested potatoes in 2002. Affected tubers showed a dull brown appearance and the lenticels and eyes on tubers turned dark brown. The cut surface of the diseased tuber colored faint pink and the entire surface of the diseased tuber becomes deep salmon pink within 30 min. The pathogen isolated from the diseased tubers was identified as Phytophthora erythroseptica based on morphological and cultural characteristics. Mycelial mat was fairly fluffy, rosette or stellate patterns and rounded or angular hyphal swellings were farmed in water, Temperature for mycelial growth was ranged from 5 to 3$0^{\circ}C$ and optimal temperature was $25^{\circ}C$. Non-papillate sporangia were persistent on stalk and ellipsoid, ovoid, obpyriform or distorted in shape, often with a constriction distal in the middle. Size of sporangia was 41.3~69.6$\times$26.8~47.4 (av, 55.5$\times$37.1) ${\mu}{\textrm}{m}$. Sexuality of Phytophthora erythroseptica was homothallic. Oogonia were 30~46 ${\mu}{\textrm}{m}$ in diameter and oospores were 28~35 ${\mu}{\textrm}{m}$ in diameter, Elongated or cyclindrical antheridia were all amphigynous. This is the first report on potato pink rot caused by Phytophthora erythroseptica in Korea.

• The Plant Pathology Journal
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• v.15 no.4
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• pp.228-235
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• 1999

Genetic diversity of ninety-five Korean isolates of Phytophthora was investigated on the basis of PCR-RFLP of ribosomal DNA. The isolates were previously identified as following fifteen species by mycological and cultural characteristics; P. boehmeriae, P. cactorum, P. cambivora, P. capsici, P. cinnamoni, P. citricola, P. citrophthora, P. cryptogea, P. drechsleri, P. erythroseptica, P. infestans, P. megasperma, P. nicotianae, P. palmivora and P. sojae. The regions of small subunit (SSU) and internal transcribed spacer (ITS) of rDNA were amplified with primer pair, NS1 and ITS4, by polymerase chain reaction (PCR) and digested with nine restriction enzymes. P. boehmeriae, P. cactorum, P. cambivora, P. capsici, P. cinnamomi, P. citricola, P. citrphthora, P. infestans, P. nicotianae and P. palmivora showed specific band patterns for each species. However, P. sojae and P. erythroseptica presented identical band patterns and P. cryptogea, P. drechsleri and P. megasperma were divided into six groups, which were not compatible with delineation of the species. A group originated from cucurbits showed distinct band patterns from other groups, but the other five groups were closely related within 96.0% similarity, forming one complex group. Consequently, Korean isolates of Phytophthora were divided into thirteen genetic groups and each group was readily differentiated by comparing digestion patterns of AvaII, HaeIII, MboI, HhaI and MspI. Therefore, PCR-RFLP of rDNA using the five enzymes can be used to differentiate or identify the Phytophthora species reported in Korea so far.

• The Plant Pathology Journal
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• v.16 no.1
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• pp.29-35
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• 2000

The internal transcribed spacer regions (ITS I, 5.8S and ITS II) of the ribosomal DNAs were amplified from Korean isolates of Phytophthora spp. and sequenced to characterize them. Sequences from 33 isolates previously identified as P. boehmeriae, P. cactprum, P. cambivora, P. capsici, P. cinnamomi, P. erythroseptica, P. infestans, P. megasperma, P. melonis, P. nicotianae, P. palmivora and P. sojae were compared with published sequences, and a phylogenetic tree was produced. All isolates belonging to 10 species, P. cactorum, P. cambivora, P. capsici, P. cinnamomi P. citricola, P. infestans, P. nicotianae, P. palmivora and P. sojae were clearly clustered into published isolates of each species above 97% bootstrap value. Cucurbits isolates of Phytophthora previously identified as either P. melonis or P. drechsleri showed distinct evolutionary lineages from the P. megasperma was closely related to isolates of P. cryptogea-P. drechsleri showed distinct evolutionary lineages from the P. cryptogea-P. drechsleri complex group, indicating that P. melonis is a valid species. A Korean isolate of P. megasperma was closely related to isolates of P. erythroseptica showed distant genetic relationship with published isolates of P. erythroseptica (CBS 956.87). It is probable that the two Korean isolates could be genetically different from foreign isolates or misidentified. A grouping of species according to ITS sequence divergence matched, to some degree, the broad classification based on type of papilla. However, a separation of semi-papillate species and papillate species was not wvident in this study.

• Korean Journal Plant Pathology
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• v.14 no.5
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• pp.519-525
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• 1998

Intraspecific genetic diversity of Korean isolates of Phytophthora drechsleri was investigated based on PCR-RFLP of rDNA along with closely related species in the genus; P. cryptogea, P. melonis, P. erythroseptica, P. cinnamomi, P. cambivora and P. cactorum. Gene regions of nuclear small subunit and internal transcribed spacer (ITS) in rDNA were amplified with polymerase chain reaction and digested with 9 restriction enzymes. Phytophthora species was readily differentiated from each other based on the digestion patterns, however, P. cryptogea was not separable from some isolates of P. drechsleri. Twenty one isolates of P. drechsleri originated from 15 host plants were divided into three distinct groups designated as PdG1, PdG2 and PdG3, respectively. Four isolates in PdG1 were originated from green vegetables and tomato and nine isolates in PdG2 were mainly isolated from medicinal plants. The two groups showed 95.3% homology and four isolates of P. cyptogea came under the groups. However, Eight isolates in PdG3 collected from cucurbits were clearly differentiated from those of PdG1 and PdG2 by 66.5% homology, but completely matched with a Taiwan isolate of P. melonis. Results indicated that three distinct groups exist in Korean isolates of P. drechleri and each group has host preference. In addition, reclassification of the cucurbits isolates are reserved because of their distinct genetic characters from other intraspecific groups in P. drechsleri.

• The Plant Pathology Journal
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• v.15 no.1
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• pp.28-33
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• 1999

Phytophthora root rot of Chniese cabbage and spinach is reported for the first time in Korea. The diseases ocurred at Yangju, Seosan and Yeocheon in Korea from 1995 through 1998, mainly in lowland and submerged areas. Symptoms consisted of stunt, yellows, wilt and eventual death due to root rot. Fourteen isolates collected from naturally infected plants were all identified as P. drechsleri based on mycological characteristics. PCR-RFLP analysis of rDNA of the isolates confirmed the above result, since the restriction band patterns of the small subunit and internal transcribed spacers were identical to P. drechsleri and P. cryptogea, but distinct from closely related species of P. erythroseptica, P. cambivora, P. sojae and P. megasperma. The pathogen showed strong pathogenicity to Chinese cabbage, moderate to spinach, radish, cabbage and tomato, and weak or none to brown mustard, kale, chicory and pepper in pathogenicity tests.