• Mycobiology
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• v.50 no.5
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• pp.269-293
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• 2022

Oomycete pathogens that belong to the genus Phytophthora cause devastating diseases in solanaceous crops such as pepper, potato, and tobacco, resulting in crop production losses worldwide. Although the application of fungicides efficiently controls these diseases, it has been shown to trigger negative side effects such as environmental pollution, phytotoxicity, and fungicide resistance in plant pathogens. Therefore, biological control of Phytophthora-induced diseases was proposed as an environmentally sound alternative to conventional chemical control. In this review, progress on biological control of the soilborne oomycete plant pathogens, Phytophthora capsici, Phytophthora infestans, and Phytophthora nicotianae, infecting pepper, potato, and tobacco is described. Bacterial (e.g., Acinetobacter, Bacillus, Chryseobacterium, Paenibacillus, Pseudomonas, and Streptomyces) and fungal (e.g., Trichoderma and arbuscular mycorrhizal fungi) agents, and yeasts (e.g., Aureobasidium, Curvibasidium, and Metschnikowia) have been reported as successful biocontrol agents of Phytophthora pathogens. These microorganisms antagonize Phytophthora spp. via antimicrobial compounds with inhibitory activities against mycelial growth, sporulation, and zoospore germination. They also trigger plant immunity-inducing systemic resistance via several pathways, resulting in enhanced defense responses in their hosts. Along with plant protection, some of the microorganisms promote plant growth, thereby enhancing their beneficial relations with host plants. Although the beneficial effects of the biocontrol microorganisms are acceptable, single applications of antagonistic microorganisms tend to lack consistent efficacy compared with chemical analogues. Therefore, strategies to improve the biocontrol performance of these prominent antagonists are also discussed in this review.

• Research in Plant Disease
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• v.17 no.2
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• pp.169-176
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• 2011

Phytophthora katsurae is the fungus responsible for chestnut ink disease. The objectives of this study were to determine if a single-strand conformation polymorphism (SSCP) analysis of rDNA-ITS region, elongation factor 1 alpha gene and ${\beta}$-tubulin gene could be used for rapid identification and genetic diversity of P. katsurae, and to assess the potential use of the SSCP technique as a diagnostic tool for P. katsurae. Each regions amplified by PCR using primers designed to overlap the genus Phytophthora were characterized for the Phytophthora species. PCR products were denatured and electrophoresed for SSCP analysis. P. katsurae isolates showed an unique pattern in SSCP analysis and were easily distinguished from other Phytophthora species used as the control. This indicates that SSCP analysis is an useful technique for distinguishing Phytophthora species from genetically close relatives, and show that the SSCP analysis of each region is an efficient detection tool for P. katsurae. But PCR-SSCP analysis of single-gene may have difficulty in distinguishing P. katsurae from other Phytophthora species. Therefore, PCR-SSCP analysis of multi-genes can be useful for rapid and effective identification of P. katsurae.

• The Plant Pathology Journal
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• v.15 no.5
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• pp.287-294
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• 1999

A technique based on the polymerase chain reaction (PCR) for the specific detection of genus Phytophthora and Phytophthora cryptogea-P. drechsleri complex group was developed using nucleotide sequence information of ribosomal DNA (rDNA) regions. The internal transcribed spacers (ITS) including 5.8S were sequenced for P. cryptogea-P. drechsleri complex group and its related species. Two pairs of oligonucleotide primers were designed. Primer pair ITS1/Phy amplified ca. 240 bp fragment in 12 out of 13 specie of Phytophthora, but not in Pythium spp., Fusarium spp.and Rhizoctonia solani. Primer pair rPhy/Pcd amplified 549 bp fragment only in P. cryptogea-P. drechsleri complex group, but not in other Phytophthora spp.and other genera. Specific PCR amplification using the primers was successful in detecting Phytophthora and P. cryptogea-P. drechsleri complex group in diseased plants.

• The Korean Journal of Mycology
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• v.38 no.1
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• pp.40-47
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• 2010

To investigate genetic relationships either interspecies or intraspecies of 14 Korean Phytophthora species, sequence analyses of nuclear DNA (ypt gene and rDNA-IGS region) and mitochondrial DNA (Cox gene, $\beta$-tubuline gene, and EF1A gene) were performed. All of 14 Korean Phytophthora species clearly clustered into foreign isolates of each species. These Korean isolates in Phytophthora species also showed no correlation between molecular classification and morphological classification like as in case of foreigners. P. palmivora KACC 40167 reported previously from genetic groups of Phytophthora species in Korea was not consistent with the classification system, and therefore was required re-examination for the genetic group analysis. Korean isolates of P. drechsleri KACC 40195 showed very close relationship with P. cryptogea KACC 40161 above 94% bootstrap value in P. cryptogea-P. drechsleri complex group. Identification of these isolates is still unclear, because P. cryptogea and P. drechsleri were not differentiated in this study. On the other hand, it was required to unify species for these two species, since P. parasitica and P. nicotianae were clustered into a group on the level of 99 to 100% sequence homology. Comparing to the sequences of foreigners, Korean isolates were newly divided to ten groups in the phylogenic system. These results could be prepared useful informations to understand genetic diversity of Phytophthora species in Korea.

• The Korean Journal of Mycology
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• v.22 no.4
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• pp.281-285
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• 1994

Zoospore progenies of Phytophthora cactorum were relatively uniform and similar to their respective parent in the rate of linear extension, whereas oospore progenies were greatly various. Also, the character of colony pattern was quantitatively various in oospore progenies but not zoospore progenies. Therefore, these results suggested that multiple genes were involved in determining growth rate and colony morphology of P. cactorum, and support the hypothesis that species of Phytophthora are diploid during the vegetative phase.

• Korean Journal Plant Pathology
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• v.14 no.6
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• pp.735-737
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• 1998

A severely wilting of strawberry caused by a Phytophthora sp. has occurred houses after planting in vinyl-houses field at Ssanglim and Anlim areas Kyungbuk in Korea from October in 1997. Phytophthora sp. isolated from diseased tissues of the crown of strawberry. Browning rot of inner crown and root resulted in wilt and eventual death of the plant. The causal fungus was identified as Phytophthora cactorum. Sporangia were ovoid, conspicuously papillate, caducous and measured 30.0~56.6$\times$23.8~35.2 (av. 39.3~29.9) ${\mu}{\textrm}{m}$. Sexuality of the fungus was homothallic. Oogonia were sperical and 23.3~32.3 (av. 29.0) ${\mu}{\textrm}{m}$ in size. Most ahteridia were paragynous and measured av. 10.2~12.2 ${\mu}{\textrm}{m}$. Cardinal temperature for growth at minimum, optium, maximum were recorded at 7, 20~25, and 32$^{\circ}C$, respectively. The fungus show strong pathogenicity to strawberry. This is the first report of strawberry caused by Phytophthora cactorum in Korea.

• Plant Disease and Agriculture
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• v.5 no.1
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• pp.58-60
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• 1999

Cultivation of a native wild vegetable, Ligularia fischeri, is hampered by Phytophthora sp. Infected plants showed wilt and eventual death due to rots on the root and basal portion. Eight isolates collected were all identified as P. drechsleri based on their mycological characteristics. The fungi showed relatively strong pathogenicity to L. Fischeri, mild to Aster scaber and Codonoposis lanceolata, and none to Circium setidens and Pimpinella brachycarpa. This is the first report of Phytophthora root rot on wild vegetables in Korea.

• The Plant Pathology Journal
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• v.22 no.3
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• pp.211-214
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• 2006

In 2004 and 2005, Phytophthora rot on Luffa cylindrica which had not been reported in Korea occurred in the experimental field at Gyeongsangnam-do Agricultural Research and Extension Services. The disease initiated on leaves and fruits of the plant with small watersoaked dark brown spots and progressed rapidly. The causal pathogen isolated from diseased tissues was identified as a Phytophthora sp. because of aseptate mycelia and zoospores released directly from sporangia. The fungus grew well on PDA and 10% V-8 juice agar showing an arachnoid or rosaceous colony pattern. Sporangia formed abundantly in water and were conspicuously papillate, noncaducous, ovoid to globose, and sized $26\sim62\times19\sim38{\mu}m$. The fungus was heterothallic as producing sexual reproduction structures only when mated with only A2 standard mating type strain. Oogonia and oospores were spherical, smooth walled, and measured as $20\sim28{\mu}m\;and\;16\sim24{\mu}m$, respectively. Oospores were aplerotic and antheridia were amphigynous, unicellula and spherical. Chlamydospores were globose and $20\sim38{\mu}m$ in diameter. Optimum temperature for growth was around $28\sim30^{\circ}C$. The fungus caused similar symptoms on artificially inoculated plant and could be re-isolated thereby proving Koch's postulation. Based on the mycological criteria investigated in this study, the causal fungus of Luffa sylindrica rot was identified as Phytophthora nicotianae. This is the first report of Phytophthora rot of Luffa cylindrica caused by P. nicotianae in Korea.

• The Plant Pathology Journal
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• v.30 no.4
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• pp.331-342
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• 2014

Given the lack of a resistant genetic pool in host plants, the introduction of exotic invasive pathogens can result in epidemics that affect a specific ecosystem and economy. Plant quarantine, which is designed to protect endemic plant resources, is a highly invaluable safeguard that should keep biosecurity with increasing international trade and global transportation. A total of 34 species of plant pathogens including Phytophthora infestans were documented as introduced from other countries into Korea from 1900 to 2010. The genus Phytophthora, classified in oomycetes, includes more than 120 species that are mostly recognized worldwide as highly invasive plant pathogens. After 2000, over 50 new species of Phytophthora were identified internationally as plant pathogens occurring in crops and forest trees. In Korea, Phytophthora is also one of the most serious plant pathogens. To date, 22 species (about one-fifth of known species) of the genus have been identified and reported as plant pathogens in the country. The likelihood of new exotic Phytophthora species being introduced into Korea continues to increase, thus necessitating intensive plant quarantine inspections. As new potential threats to plant health in Korea, six Phytophthora species, namely, P. alni, P. inundata, P. kernoviae, P. pinifolia, P. quercina, and P. ramorum, are discussed in this review with focus on history, disease, biology, management, and plant quarantine issues.

• Research in Plant Disease
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• v.11 no.1
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• pp.72-76
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• 2005

In 2002 and 2003, Phytophthora blight on Daphne odora occurred in fields at Waryong Mountain, Sacheon city, Korea. The disease usually initiated on the root and crown of the plant. Crown lesions began with light brown as water-soaking. Infection rate of the disease reached up to 60% in a heavily infested fields. The causal fungus was identified as Phytophthora nicotianae based on following mycological characteristics. Sporangium: readily formed in water, papillate, noncaducous, ovoid to spherical, 23~$56{\times}$~34 $\mu\textrm{m}$ in size. Oogonium: spherical, smooth walled, 18~26 $\mu\textrm{m}$ in size. Oospore: aplerotic, globose, 16~24 $\mu\textrm{m}$ in size. Antheridium: amphigynous, unicellula, spherical. Chlamydospore: abundant, spherical, 16~32 $\mu\textrm{m}$ in size. Sexuality: heterothallic. Optimum growth temperature was about 25~$30^{\circ}C$. Pathogenicity of the isolate was confirmed on host plant and the fungus was identified as Phytophthora nicotianae. This is the first report of Phytophthora blight of Daphne odora in Korea.