• Korean Journal Plant Pathology
• /
• v.3 no.4
• /
• pp.252-260
• /
• 1987

Incidence of lettuce drop was observed throughout the growing season in the vinylhouse at the southern part of Korea, Kimhai. Occurrence of this disease was especially severe at the seedling stage. Number of sclerotia in surface soil $(30\times30\times5cm)$ was 22.0 at the seedling stage, and 5.3 at harvest in the infected area. Temperature for mycelial growth ranged from 5 to $30^{\circ}C$ with optimum temperature at $25^{\circ}C$. Sclerotia were formed fewer at low temperature, but their size was larger resulting in heavier dry weight than that at high temperature. The apothecia were formed from the sclerotia that were buried in March, April and September upto 3cm soil depth, but formed from those buried only 1 em soil depth in October. Sclerotia buried in June and December did not form apothecia regardless of soil depth by 90 days. The sclerotia buried in the 5cm of soil depth did not form apothecia. Sclerotia that were embedded in wet or flooded soil at $25^{\circ}C$ and $30^{\circ}C$ for 5 weeks lost their viability. Infection of lettuce was possible with mycelia originated from sclerotia on autoclaved lettuce plant fragments. The fungus was pathogenic on 25 plant species in 8 families in artificial inoculation tests. Lettuce seedlings appeared to be infected by airborne ascospore originated from sclerotia on crops and weeds around paddy fields, because sclerotia existing in soil might perish under long flood conditions during rice cultivation.

• Journal of Marine Bioscience and Biotechnology
• /
• v.2 no.1
• /
• pp.34-39
• /
• 2007

Penaeidins are members of a special family of antimicrobial peptides existing in several species of shrimp and play a crucial role in the immunological defense of shrimp. In this study, we isolated and characterized one EST clone (penaeidin) from cDNA library of fleshy prawn Fenneropenaeus chinensis hemocytes. Amino acids sequence comparison and phylogenetic analysis with other known penaeidins revealed that our clone was completely identical to F. chinensis Penaeidin 3-2 (Accession no. ABC33920), which composed of 71 amino acids with a putative signal peptide (1-19) and a cysteine-rich domain (C-terminal part). The expression and distribution of Penaeidin 3-2 transcripts in shrimp were detected in hemocytes, hepatopancreas, and muscles, and that Penaeidin 3-2 was constitutively expressed mainly in hemocytes. The artificial infection of white spot syndrome virus to F. chinensis resulted in Penaeidin 3-2 mRNA up-regulation in hemocytes, suggesting that the possible role of Penaeidin 3-2 in host defense system of F. chinensis.

• Korean journal of applied entomology
• /
• v.19 no.4 s.45
• /
• pp.193-198
• /
• 1980

This paper deals with the studies on the occurence of a new virus disease of sesame and the identification of the causal virus. The virus disease of sesame has been regarded as a widespread disease in the sesame-growing areas in the southern part of Korea. The disease was found to be caused by watermelon mosaic virus (WMV). During the years since 1978, stunting of sesame plants, with yellow mosaic, necrotic spot, and malformation, were collected from 17 different places. Virus isolates from 27 out of 32 samples were identified as WMV. Natural infection of squash, pumpkin, cucumber, and watermelon by WMV as well as sesame was proved. The virus is inactivated at temperatures of 55 to $60^{\circ}C$, at dilution of $10^{-3}\;to\;10^{-4}$, and in the aging of 10 to 14 days at about $20^{\circ}C$. Sesame, Chenopodium amaranticelor, pea, bean, as well as many plants of the Cucurbitaceae, are susceptible to the sesame-isolates of WMV. In negatively stained preparations, particles of the virus appear under the electron microscope as flexible filaments of about $750\~800nm$ in length. Cylindrical inclusions and virus particles were found in the cytoplasm of mesophyll cells by ultra-thin sections of WMV infected tissues.

• Korean journal of applied entomology
• /
• v.48 no.4
• /
• pp.479-484
• /
• 2009

A leafhopper, Zorka sp. was collected from a persimmon (Diospyrosi kaki, cv SangjuDungsi) orchard in Sangju, Gyeongsangbuk-do, Korea on 15 June, 2008. This leafhopper gave a serious damage to persimmon leaves, being a new pest to persimmon. This leafhopper was tentatively identified as Zorka sp., which has not been recorded in the science. White spots of <1mm-circle occurred around the vein of damaged leaves. Most part of leaf was turned to white when heavy infection occurred. The first symptom occurred from 4 days after introduction of Zorka sp. (4 adults/persimmon leaf). We investigated the occurrence of Zorka sp. in the persimmon orchards in Korea from 2008 to 2009. Total 143 orchards from 11 cities in 6 provinces were observed from July to August. The damage caused by Zorka sp. was found in 22 orchards (15.4%) of the investigated. According to locality, 40.7% of orchards were damaged in Yeongdong, Chungcheongbuk-do and 33.3% in Wanju, Jeollabuk-do. However, no damage was observed from the orchards in Gyeongsangnam-do and Jeju-do, south part of Korea. Especially, 9 of 11 orchards in Youngdong were located close to grapevine yards.

• The Plant Pathology Journal
• /
• v.28 no.1
• /
• pp.32-39
• /
• 2012

Efficacy of different control methods was evaluated for disease management of tomato bacterial wilt caused by $Ralstonia$ $solanacearum$. All six chemical pesticides applied to the bacterial suspension showed $in$ $vitro$ bactericidal activities against $R.$ $solanacearum$. Minimal inhibitory concentrations (MICs) of copper hydroxide (CH), copper hydroxide-oxadixyl mixture (CH+O), and copper oxychloride-dithianon mixture (CO+D) were all 200 ${\mu}g/ml$; MIC of copper oxychloride-kasugamycin (CO+K) mixture was 100 ${\mu}g/ml$; MICs of both streptomycin- validamycin (S+V) and oxine copper-polyoxine B mixture (OC+PB) were 10 ${\mu}g/ml$. Among these chemical pesticides, treatment of the detached tomato leaves with the 5 pesticides (1 mg/ml), except for OC+PB delayed early wilting symptom development caused by the bacterial inoculation ($10^6$ and $10^7$ cfu/ml). Four pesticides, CH, CH+O, CO+K and S+V, showed disease protection in pot analyses. Six plant essential oils, such as cinnamon oil, citral, clove oil, eugenol, geraniol and limonene, differentially showed their antibacterial activities $in$ $vitro$ against $R.$ $solanacearum$ demonstrated by paper disc assay. Among those, cinnamon oil and clove oil exert the most effective activity for protection from the wilt disease caused by the bacterial infection ($10^6$ cfu/ml). Treatment with cinnamon oil and clove oil also suppressed bacterial disease by a higher inoculum concentration ($10^7$ cfu/ml). Clove oil could be used for prevention of bacterial wilt disease of tomato plants without any phytotoxicity. Thus, we suggest that copper compounds, antibiotics and essential oils have potency as a controlling agent of tomato bacterial wilt.

• The Plant Pathology Journal
• /
• v.29 no.4
• /
• pp.386-396
• /
• 2013

Reactive oxygen species (ROS) generation in tomato plants by Ralstonia solanacearum infection and the role of hydrogen peroxide ($H_2O_2$) and nitric oxide in tomato bacterial wilt control were demonstrated. During disease development of tomato bacterial wilt, accumulation of superoxide anion ($O_2{^-}$) and $H_2O_2$ was observed and lipid peroxidation also occurred in the tomato leaf tissues. High doses of $H_2O_2$ and sodium nitroprusside (SNP) nitric oxide donor showed phytotoxicity to detached tomato leaves 1 day after petiole feeding showing reduced fresh weight. Both $H_2O_2$ and SNP have in vitro antibacterial activities against R. solanacearum in a dose-dependent manner, as well as plant protection in detached tomato leaves against bacterial wilt by $10^6$ and $10^7$ cfu/ml of R. solanacearum. $H_2O_2$- and SNP-mediated protection was also evaluated in pots using soil-drench treatment with the bacterial inoculation, and relative 'area under the disease progressive curve (AUDPC)' was calculated to compare disease protection by $H_2O_2$ and/or SNP with untreated control. Neither $H_2O_2$ nor SNP protect the tomato seedlings from the bacterial wilt, but $H_2O_2$ + SNP mixture significantly decreased disease severity with reduced relative AUDPC. These results suggest that $H_2O_2$ and SNP could be used together to control bacterial wilt in tomato plants as bactericidal agents.

• Research in Plant Disease
• /
• v.19 no.2
• /
• pp.84-89
• /
• 2013

The incidence factors of Rice stripe virus (RSV) were analyzed by studying the population density and the viruliferous insect rate (VIR) of small brown planthopper (SBPH), the incidence of stripe disease, alternate host, and susceptible cultivar in Chungnam Province. The population of overwintering SBPH had been decreasing, but the VIR of overwintering SBPH had not been differing for three years, 2008 to 2010. No RSV was detected in the natural host plants, such as short awn, annual bluegrass, and barley. In 2009, relatively large population of SBPH with the VIR of 5.4% migrated from China. However, there was no evidence relating of migration large amount of SBPH from China in 2008 and 2010. Also the infection rate of RSV in rice was less than 1% in these periods. The cultivation area of the susceptible varieties had steadily decreased from 41% to 19% from 2007 to 2009. Therefore, the reduction factors of rice stripe disease in Chungnam Province with higher influx of inoculum could be with an appropriate forecasting and chemical control, cultivation of resistant varieties, changes in the cropping system, and the low winter-spring temperature.

• Korean Journal of Soil Science and Fertilizer
• /
• v.41 no.5
• /
• pp.362-368
• /
• 2008

In order to isolate novel oligotrophic bacteria exhibiting antifungal activities, soils were collected from pepper-cultivated fields of Yeongyang, Jecheon, Nonsan, Eumsong and Goesan area in Korea. From soils in pepper cultivated area, a total of 9,354 strains were isolated as oligotrophic bacteria by the R2A dilution method. Among 9,354 oligotrohic bacteria candidates, 1A strain was selected by screening against Phytophthora capsici causing phytophthora blight of hot pepper in the greenhouse and field. The strain was identified as Bacillus vallismortis based on its 16S rDNA sequence and key characteristics as compared with those of authentic cultures of B. vallismortis(KACC 12149) and B. mojavensis(KACC 12096). The strain showed broad spectrum of antibiotic activity in vitro test, as revealed in its strong inhibitory activity to the genera Phytophthora, Collectotrichum, Botrytis and Fusarium, but not to Rhizoctonia and Magnaporthe. In pot experiments, infection rate of hot pepper in the non-treated pots was about 89%, while it was only 29% in the pots treated with 1A strain. The result indicated B. vallismortis 1A is a potential biocontrol agent for phytophthora blight of hot pepper

• Asian-Australasian Journal of Animal Sciences
• /
• v.27 no.10
• /
• pp.1461-1468
• /
• 2014

This study was aimed to examine the antibacterial and antioxidative properties of seven edible plants from Thailand to develop alternative antibiotics as feed additives. The plants include Citrus aurantifolia Swingle (Lime) fruits and its leaves, Sesbania grandiflora L. (Agati sesbania) leaves, Piper sarmentosum Roxb (Wild betal) leaves, Curcuma domestica Valeton (Turmeric) roots, Morinda citrifolia L. (Beach mulberry) leaves, Cassia siamea britt (Siamea cassia) leaves, and Cocos nucifera L. (Coconut) peels. The plants were extracted by methanol, n-hexane, chloroform, ethyl acetate, butanol and water. Antibacterial activities with minimum inhibitory concentration (MIC) were determined by agar diffusion assay against Escherichia coli, Burkholderia sp., Haemopilus somnus, Haemopilus parasuis, and Clostridium perfringens that were considered pathogenic strains in livestock infection. Methanol extracts of C. aurantifolia Swingle fruits and leaves showed the broadest spectrum of antibacterial activities except for C. perfringens. Butanol extract of S. grandiflora L. leaves showed the strongest activity against Burkholderia sp. with MIC, $135{\mu}g/mL$. P. sarmentosum Roxb leaves showed antibacterial activities against E. coli, Burkholderia sp. and H. parasuis. Ethyl acetate and water extracts from C. domesitca Valeton roots showed MIC of $306{\mu}g/mL$ and $183{\mu}g/mL$, respectively against only C. perfringens. Antioxidative activity was determined by 2-diphenyl-2-picryl hydrazyl photometric assay. The methanol extracts of C. aurantifolia Swingle fruits and P. sarmentosum Roxb leaves showed the highest antioxidant activity among all the extracts with 3.46 mg/mL and 2.70 mg/mL effective concentration 50% ($EC_{50}$) values, respectively. Total contents of phenolics and flavonoids were measured from the plant extracts. Methanol extracts of S. grandiflora L. and chloroform extracts of C. domestica Valeton were found to have the highest amount of total phenolics, 41.7 and $47.8{\mu}g/mL$, respectively. Flavonoid content of methanol extracts in S. grandiflora L. T was $22.5{\mu}g/mL$ and the highest among plant extracts tested. These results indicated that C. aurantifolia Swingle, S. grandiflora L., P. sarmentosum Roxb, and C. domestica Valeton have antibacterial and antioxidant activities and can be used as alternative antibiotics or potential feed additives for the control of animal pathogenic bacteria.

• BMB Reports
• /
• v.49 no.10
• /
• pp.554-559
• /
• 2016

Mycobacterium abscessus, a member of the group of non-tuberculous mycobacteria, has been identified as an emerging pulmonary pathogen in humans. However, little is known about the protective immune response of antigen-presenting cells, such as dendritic cells (DCs), which guard against M. abscessus infection. The M. abscessus gene MAB1843 encodes ᴅ-alanyl-ᴅ-alanine dipeptidase, which catalyzes the hydrolysis of ᴅ-alanyl-ᴅ-alanine dipeptide. We investigated whether MAB1843 is able to interact with DCs to enhance the effectiveness of the host's immune response. MAB1843 was found to induce DC maturation via toll-like receptor 4 and its downstream signaling pathways, such as the mitogen-activated protein kinase and nuclear factor kappa B pathways. In addition, MAB1843-treated DCs stimulated the proliferation of T cells and promoted Th1 polarization. Our results indicate that MAB1843 could potentially regulate the immune response to M. abscessus, making it important in the development of an effective vaccine against this mycobacterium.