• Korean Journal Plant Pathology
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• v.14 no.5
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• pp.445-451
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• 1998

A severe Phytophthora rot of strawberry caused by a species of Phytophthora has been widely occurred at major cultivation areas of Kimhae on August in 1997. Incidence of the disease was obtained in the range of 69.2~83.6% in surveyed 4 fields and showed an average of 75.2%. A species of Phytophthora was mostly isolated from the crown of infected strawberry plants and all the isolates were identified as P. nicotianae var. nicotianae (=P. parasitica). The fungus showed strong pathogenicity on strawberry by inoculation test. As a result of the leaf inoculation using mycelial disks of the fungus, both leaves and petioles were darkly browned, and were finally blighted. As a result of the root inoculation of zoospore suspension, both roots and crowns were rotten with dark brown. Although the fungus produced sporangia either on V-8 juice agar medium or liquid medium, the sporangia observed on the liquid medium appeared to be broadly turbinate and noncaducous. Moreover the fungus cultured on the liquid medium often produced sporangia having two papilla. The number of zoospores in sporangia was found to be ranged from 3 or 4 to as many as 20 or 25. In addition, the released zoospore from the sporangium became the cystospore during the prolonged culture of the fungus. The sporangia were measured as av. 49$\times$35 ${\mu}{\textrm}{m}$ with l/b ratio of 1.43. All isolates from crowns were heterothallic and A1 mating type since oospores were abundantly formed on clarified V-8 juice agar by dual culture with P. capsici A2 mating type. Aplerotic oospores were sized 24-26 ${\mu}{\textrm}{m}$. Antheridia were always amphigynous and recoreded an average of 12$\times$10 ${\mu}{\textrm}{m}$. Hyphal swlling were easily observed, and terminal or intercalary chlamydospores were abundantly formed on V-8 juice agar as well as in C/Z solution and sized av. 28.2 ${\mu}{\textrm}{m}$. This is the first report of Phytophthora rot of strawberry in Korea.

• Research in Plant Disease
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• v.16 no.2
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• pp.158-162
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• 2010

Four promising biocontrol agents against Phytophthora capsici were selected from 507 bacterial isolates collected from rhizosphere soils and roots of pepper plants. In vitro experiment, these four biocontrol agents inhibited mycelial growth, germination of cystospores, and formation of zoosporangia and zoospores of Phytophthora capsici. In the pot experiment, the four biocontrol agents showed control efficiency higher than 70%. In greenhouse experiment, the isolates G28-6 gave the control value of 79.4%. These four biocontrol agents successfully colonized in the population density beyond 105 cfu/g on roots of pepper in vitro. The isolates G28-6 was identified as Pseudomonas aurantiaca, based on its cultural, morphological, and biochemical characterization and 16S rRNA gene sequence analysis.

• Korean Journal of Plant Tissue Culture
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• v.26 no.3
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• pp.177-182
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• 1999

A fungal infection assay between normal and transgenic potato harboring chitinase gene in cultivar Belchip was investigated. In the first stage of experiment, seven transgenic lines having 12cm tall were tested for their resistance against potato late blight pathogen Phytophthora infestans by infection with the zoospores, artificially, Susceptibility to potato late blight infection could be classified into three types based on the rate. In terms of resistance to the disease, two lines were higher, two lines were more suppressive, and three lines were similar as compared with the control. In the following experiment, only 2 risistant lines and 1 suppressed line were used to confirm the resistance again. The results of both experiments were similar. Furthermore, two highly resistant transgenic lines grown in field exhibited a higher resistance than control under the conditions of natural ocurrence of the fungal disease.

• Korean Journal of Veterinary Service
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• v.34 no.1
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• pp.55-61
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• 2011

Dermatopathologic findings on cutaneous streptothricosis (bovine dermatophilosis) were conducted in Dinajpur of Bangladesh for one year. The animals were examined clinically at hospital during the physical visit of the affected animals and clinical manifestations and patients' history were recorded. The gross lesions were systematically examined, noted and categorized. An impression smear was made by the skin scraps, stained with Gram's stain and examined microscopically for the presence of causative bacteria. The suitable sizes of skins of 3 animals typically affected with dermatophilosis were collected surgically from the animals, and prepared for the histopathological study. The cardinal clinical features and gross lesions were characterized as paint-brush cutaneous surface with matted hairs, scab and crust formation, roughened coat; istopathologically as hyperkeratosis, parakeratosis, typical "palisading encrustations", extensive proliferation of coccoid shaped, bluish coloured bacteria (zoospores) in the cells of the outer rootsheath of the hair follicles, separation of keratinized layer from the epidermal epithelium, epidermal hyperplasia, densely cellular dermis with moderate destruction of glandular structures. Coccoid shaped gram positive organisms which form multidimensional arrangement were also observed by impression smear. The clinical signs, gross lesions, morphology of the organisms, staining properties, and histopathological features of the affected skin were diagnostic criteria for the bovine cutaneous streptothricosis.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.5
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• pp.315-322
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• 2007

Kjellmaniella crassifalia Miyabe is one of the valuable seaweed crops cultured in the Korean coastal waters of the East Sea. Unfortunately recent environmental changes have adversely influenced its growth, prompting the need to develop techniques for species restoration. To obtatin biological information, the growth of the species was monitored for one year. The maximum blade length, $110{\pm}45cm$, was attained in July, and zoospores were released in November. The optimum culture conditions allowing juvenile sporophytes to grow to young blades consisted of $20{\mu}mol/m^2s\;at\;10^{\circ}C$ under which the blade length grew to $1,732.5{\pm}143.3{\mu}m$ in 42 days. Sporangial sori started to form in September, reaching 85% maturity in November and 89% maturity in December. Examining the growth of the species according to depth, the individuals growing at 5 meters grew the most, reaching a blade length of $75.9{\pm}18.9cm$ in August.

• Korean Journal of Environmental Biology
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• v.31 no.4
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• pp.347-352
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• 2013

Outdoor cultivation experiment was conducted with artificial seeds using free-living gametophytes and zoospores of Ecklonia cava to develop FLG (free-living gametophyte) seeding technique. Growth of thalli between FLG and zoospore seeding groups was compared monthly from May to October 2009 at culture farm in Wando, Korea. In September 2009, thalli in the FLG seeding experimental group were $35.9{\pm}0.8$ cm in length, $24.1{\pm}2.62$ g in weight, $2.32{\pm}0.26$ kg $m^{-1}$ in biomass and $22.0{\pm}2.8$ individuals $m^{-1}$ in density. There were no significant differences in length, weight, biomass and density between FLG and zoospore seeding group. Therefore, the FLG seeding technique could replace the zoospore seeding method which would eventually contribute in restoration and conservation of natural resources.

• The Plant Pathology Journal
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• v.36 no.3
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• pp.244-254
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• 2020

Gom-chwi (Ligularia fischeri) is severely infected with Phytophthora drechsleri, the causal organism of Phytophthora root rot, an economically important crop disease that needs management throughout the cultivation period. In the present study, Phytophthora root rot was controlled by using bacterial isolates from rhizosphere soils collected from various plants and screened for antagonistic activity against P. drechsleri. A total of 172 bacterial strains were isolated, of which, 49 strains showed antagonistic activities by dual culture assay. In the seedling assay, six out of the 49 strains showed a predominant effect on suppressing P. drechsleri. Among the six strains, the ObRS-5 strain showed remarkable against P. drechsleri when treated with seed dipping or soil drenching. The ObRS-5 strain was identified as Enterobacter asburiae based on 16S ribosomal RNA gene sequences analysis. The bacterial cells of E. asburiae ObRS-5 significantly suppressed sporangium formation and zoospore germination in P. drechsleri by 87.4% and 66.7%, respectively. In addition, culture filtrate of E. asburiae ObRS-5 also significantly inhibited sporangium formation and zoospore germination by 97.0% and 67.6%, respectively. Soil drenched bacterial cells, filtrate, and culture solution of E. asburiae ObRS-5 effectively suppressed Phytophthora root rot by 63.2%, 57.9%, and 81.1%, respectively. Thus, E. asburiae ObRS-5 could be used as a potential agent for the biological control of Phytophthora root rot infecting gom-chwi.

• The Plant Pathology Journal
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• v.36 no.6
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• pp.600-607
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• 2020

Phytophthora capsici Leonian is a major pathogen of pepper worldwide and few resistance sources to this pathogen have been identified so far. The goals of this study were to identify new sources of resistance against P. capsici in Capsicum landraces and analyze the relationship between the resistance indicator of plant symptoms and some plant phenotype parameters of plant height, stem width, leaf length and leaf width. Thirty-two landraces of pepper were collected from fourteen states in Mexico. From each population, 36 plants were inoculated with 10,000 zoospores of P. capsici under controlled conditions. This experiment was repeated twice. Out of the 32 landraces, six showed high level of resistance, four showed intermediate resistance and five showed low level of resistance when compared with the susceptible control 'Bravo' and the resistant control 'CM334', indicating that these landraces are promising novel sources of resistance to P. capsici. There was no correlation between the symptoms and plant phenotype parameters. However, these parameters were not affected in the group classified as highly resistant, indicating that P. capsici does not affect the growing of these resistant pepper landraces. The other resistant groups were significantly affected in a differently manner regarding their phenotype, indicating that this pathogen reduce their growth in different ways. This study reports novel resistance sources with great potential that could be used in breeding programs to develop new pepper cultivars with durable resistance to P. capsici.

• The Korean Journal of Malacology
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• v.26 no.3
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• pp.211-215
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• 2010

The genus Perkinsus are parasitic protozoans that cause massive inflammatory responses in infected marine shellfish worldwide. This ultimately leads to great economic losses. This study examined the effects of water temperature and salinity on the formation of prezoosporangia and zoosporangia in order to understand the ecology of the pathogens. The induction of prezoosporangia from trophozoites occurred readily at higher water temperatures (20 and $30^{\circ}C$) and they had larger diameters than those incubated at lower temperatures (4 and $10^{\circ}C$). The formation of zoospores in prezoosporangia was also strongly influenced by water temperature and salinity; prezoosporangia exposed to water temperatures of 20 and $30^{\circ}C$ and salinities of 20 and 30 ppt had high rates of zoosporulation, while no or very low rates of zoosporulation were observed at temperatures below $10^{\circ}C$ or salinity below 10 ppt. Our data will be useful for the development of strategies to counter P. olseni proliferation in Korean waters.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.1
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• pp.46-54
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• 2014

This study was conducted to investigate the effects of eucalyptus (E. Camaldulensis) crude oils (EuO) supplementation on voluntary feed intake and rumen fermentation characteristics in swamp buffaloes. Four rumen fistulated swamp buffaloes, body weight (BW) of $420{\pm}15.0$ kg, were randomly assigned according to a $2{\times}2$ factorial arrangement in a $4{\times}4$ Latin square design. The dietary treatments were untreated rice straw (RS) without EuO (T1) and with EuO (T2) supplementation, and 3% urea-treated rice straw (UTRS) without EuO (T3) and with EuO (T4) supplementation. The EuO was supplemented at 2 mL/h/d in respective treatment. Experimental animals were kept in individual pens and concentrate mixture was offered at 3 g/kg BW while roughage was fed ad libitum. Total dry matter and roughage intake, and apparent digestibilites of organic matter and neutral detergent fiber were improved (p<0.01) by UTRS. There was no effect of EuO supplementation on feed intake and nutrient digestibility. Ruminal pH and temperature were not (p>0.05) affected by either roughage sources or EuO supplementation. However, buffaloes fed UTRS had higher ruminal ammonia nitrogen and blood urea nitrogen as compared with RS. Total volatile fatty acid and butyrate proportion were similar among treatments, whereas acetate was decreased and propionate molar proportion was increased by EuO supplementation. Feeding UTRS resulted in lower acetate and higher propionate concentration compared to RS. Moreover, supplementation of EuO reduced methane production especially in UTRS treatment. Protozoa populations were reduced by EuO supplementation while fungi zoospores remained the same. Total, amylolytic and cellulolytic bacterial populations were increased (p<0.01) by UTRS; However, EuO supplementation did not affect viable bacteria. Nitrogen intake and in feces were found higher in buffaloes fed UTRS. A positive nitrogen balance (absorption and retention) was in buffaloes fed UTRS. Supplementation of EuO did not affect nitrogen utilization. Both allantoin excretion and absorption and microbial nitrogen supply were increased by UTRS whereas efficiency of microbial protein synthesis was similar in all treatments. Findings of present study suggested that EuO could be used as a feed additive to modify the rumen fermentation in reducing methane production both in RS and UTRS. Feeding UTRS could improve feed intake and efficiency of rumen fermentation in swamp buffaloes. However, more research is warranted to determine the effect of EuO supplementation in production animals.