• Korean Journal of Medicinal Crop Science
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• v.14 no.6
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• pp.336-341
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• 2006

The endophytic bacteria were isolated from the rusty-root ginseng. This isolated bacteria were occurred the rusty-root ginseng with artificial inoculation. For the suppressing of rusty-ginseng, disinfectants, antibiotics, kitosan, micro-organisms and metabolites were tested to isolated endophytic bacterium. All of the isolated bacteria strains were sensitive sodium hypochlorite, however, some of isolated bacteria lines were sensitive to other tested materials. For example, D (didecyl dimethyl ammonium bromide), CIO$_2$, ODDA (octyldecyl dimethyl ammonium chloride + diocyul dimethyl ammonium chloride + alkyl diethyl benzyl ammonium chloride), GD (glutaraldehyde + dimethy cocobenzyl ammonium chloride) suppressed some of bacteria strains. Otherwise, some of antibiotics (e.g. ampicillin, chloramphenicol, erythromycin, kanamycin, neomycin, rifampin, streptomycin, tetracycline) were sensitive to the isolated bacteria strains. All of isolated bacteria strainswere inhibitive to the mixed formation with neomycin and streptomycin, and neomycin and tetracycline. Both sodium hypochlorite and antibiotic mixing of neomycin and tetracycline were effective to prevention of rusty-root ginseng of sub-merging ginseng in the ginseng field.

• The Plant Pathology Journal
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• v.17 no.3
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• pp.154-158
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• 2001

A severe root rot of kiwifruit caused by a species of Phytophthora occurred in 1-to 5-year-old vines at the south coast region of Korea in 1997. Infected vines exhibited leaf chlorosis, scorch and defoliation, root and stem rot, and eventual death. The disease was relatively severe in poorly drained lowlands, of which 19 out of 23 fields were damaged by the disease. Meanwhile, only one among 58 upland fields was infected by the disease. Incidence of infected vines reached over 80% in heavily damaged fields and a species of Phytophthora was isolated from inner tissues of roots, stems, and rhizosphere soils of the plants. The causal pathogen was identified as P. drechsleri based on its mycological characteristics. Pathogenicity of the fungus was confirmed by artificial inoculation to seedlings of kiwifruit 'Hayward'. The pathogen was re-isolated from the inoculated plants showing symptoms similar to those observed in the fields. Root rot of kiwifruit caused by P. drechsleri has not been reported previously in Korea.

• Journal of Mushroom
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• v.18 no.3
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• pp.208-213
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• 2020

Burkholderia contaminans PSB-A and Burkholderia ambifaria PSB-B were isolated from button mushroom bed to estimate their phosphate solubility. The phosphate-solubilizing abilities of these strains were assessed by measuring the phosphorus content in a single and co-inoculation medium for 7 days. The co-inoculation of these two strains released the highest content of soluble phosphorus (166.3 ㎍ mL^-1) into the medium, followed by single inoculation of B. contaminans PSB-A (143.73 ㎍ mL^-1) and B. ambifaria PSB-B (127.1 ㎍ mL^-1). The highest pH reduction, organic acid production, and glucose consumption were also observed in the co-inoculation medium. According to the plant growth promotion bioassay, co-inoculation enhanced the growth of romaine lettuce much more than the single inoculation (20.4% for leaf widths and 16.6% for root lengths). Although no significant difference was noted between single and co-inoculation of bacterial strains in terms of phosphorous release and plant growth, co-inoculation of PSB may have a beneficial effect on crop growth due to a synergistic effect between the strains.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.6
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• pp.718-724
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• 1996

Two soybean cultivars, ‘Lee’ and ‘Peking’, were used to evaluate the competition and interaction of rhizobium strains PRC205 (R. fredii, fast-grower) and USDA110 (B. japonicum, slow-grower). Strains were inoculated separately on the root parts of a split-root growth system. Both root sides were inoculated simultaneously with four combinations of strain treatment to evaluate the competition of strains. And to evaluate the interaction of strains one side of split-root system was inoculated a week prior to the other side. Nodule mass and dry weight of the plants were measured 3 weeks after treatments. PRC205 showed no effective nodulation and no competing ability with USDA110 on Lee cultivar, however, contrary results on Peking cultivar. Top dry weight of Lee inoculated with PRC205 was much lower than that of any other inoculation treatments, however, in Peking that with PRC205 was higher than that with USDA110. There were no differences in root dry weight among the inoculation treatments. USDA110 used as primary inoculant suppressed nodule mass of opposite side, secondary inoculant, severely in both cultivars. PRC205 showed same tendency as USDA110 in Peking, but revealed little suppression effects on USDA110 used as secondary inoculant in Lee. USDA110 used as primary inoculant in Lee and PRC205 in Peking showed much more dry weight of soybean plants than that of other treatments.

• The Korean Journal of Mycology
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• v.45 no.1
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• pp.74-82
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• 2017

Lisianthus (Eustoma grandiflorum) is a flowering ornamental plant used widely in Korea. In 2015, wilting, damping-off, stunting, and root rot symptoms were observed in lisianthus plants of Yeoju and Gimhae, Korea. Affected seedlings appeared yellow and showed poor development of root systems in the field and in nursery boxes. Furthermore, affected plants were yellow, stunted, and died at approximately 2-3 months after transplanting. Fusarium species were consistently isolated from the basal stems of diseased plants. Nine isolates were identified as Fusarium solani based on morphological characteristics. Macroconidia of isolates were relatively wide, straight-to-slightly curved, and microconidia formed in false heads on long monophialides. Abundant chlamydospores were produced at the middle or tips of hyphae. To confirm this identification, a molecular analysis of the translation elongation factor 1 alpha (TEF) and RNA polymerase II subunit (RPB2) genes was conducted. The sequences of TEF and RPB2 showed 99.2-99.9% and 98.0-98.1% similarity, respectively, to those of reference F. solani strains in NCBI GenBank. Pathogenicity was tested using root dipping inoculation of healthy lisianthus seedlings. Symptoms were observed within 7 days of inoculation only in inoculated plants. This is the first report of F. solani causing Fusarium root rot on lisianthus in Korea.

• Korean Journal Plant Pathology
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• v.13 no.3
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• pp.160-166
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• 1997

Number of bacterial isolates were collected from high mountainous areas at various locations in the whole country to select promising biocontrol agents. Most of selected isolates belonged to fluorescent pseudomonads. Population densities of fluorescent pseudomonads were examined by DLF method. Alll selected isolates rapidly multiplied on spermosphere after seed inoculation upto 24, and then the population abruptly declined. When seeds were germinated fully, bacteria moved to newly emerging radicle. The good root colonizing isolates, B16 and V13 proliferated on the growing root and moved down to the root tip and lateral roots. but the poor root colonizing isolates, MC07 and X01 moved much slower. Scanning electron microscopic observations showed that the cells of the good colonizing isolates were arranged linearly on the growing root and parallel to growing root axis and continuously existed on the root tip, Whereas the cells of poorly colonizing isolates were gathered and scattered randomly on the root surface.

• Journal of Plant Biotechnology
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• v.29 no.1
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• pp.31-36
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• 2002

The patterns of adventitious root formation from cotyledons for each cultivar of soybeans were compared. The results of adventitious root formation in cultivars are classified as two groups; the first group showed the direct adventitious root formation, and the second group resulted in the callus and adventitious root formation. The cultivars that have much callus formation had less the adventitious root formation. The adventitious root formation in the cotyledonary explants was occured only at the inoculation of adaxial side. When adaxial and abaxial side was inoculated simultaneously, the adventitious roots were formed at the adaxial side. Thus, it suggests that there must be direction to some extent. Starch in the cotyledonary explants were more abundant at the 4 days after induction than at the early stage of the adventitious root formation, but the starch was not observed after 7 days, that the growth stage of adventitious roots.

• Journal of the Korean Society of Tobacco Science
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• v.30 no.1
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• pp.1-7
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• 2008

Bacterial wilt caused by Ralstonia solanacearum has become a severe problem on tobacco in Korea. No effective single control measure is available at present time. One of the most potential way for controlling the bacterial wilt on tobacco is growing tobacco cultivars resistant to the bacterial wilt. In this study, optimal conditions for screening tobacco cultivars resistant to the bacterial wilt were examined to provide reproducible and efficient methods in growth chamber testing and field experiments for evaluating plant disease resistance. For this, already-known inoculation methods, inoculum densities, and incubation temperature, and plant growth stages at the time of inoculation were compared using tobacco cultivars resistant (Nicotiana tabacum cv, NC95), moderately resistant (N. tabacum cv. SPG70), and susceptible (N. tabacum BY4) to the bacterial disease. It was determined that root-dipping of tobacco seedlings at six true leaf stage into the bacterial suspension with inoculum level of $10^8$ colony-forming units (CFU)/ml for 20 min before transplanting was simple and most efficient in testing for resistance to the bacterial wilt of tobacco caused by R. solanacearum, for which disease incidences and severities were examined at 2 weeks of plant growth after inoculation at $20{\sim}25^{\circ}C$ in a growth chamber. These experimental conditions could discriminate one tobacco cultivar from the others by disease severity better than any other experimental conditions. In field testing, the optimum time for examining the disease occurrence was late June through early July. These results can be applied to establishing a technical manual for the screening of resistant tobacco cultivars against the bacterial wilt caused by R. solanacearum.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.1
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• pp.51-58
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• 2012

Salinity is one of the most relevant abiotic factor limiting crop yield and its net primary productivity. In addition, salinity induces an increased stress ethylene synthesis in plants which, in turn, exacerbate the responses to the stressor. Bacterial single or co-inoculation effect was tested using previously characterized plant growth promoting (PGP) bacteria Brevibacterium iodinum RS16 and Methylobacterium oryzae CBMB20 on maize and sorghum-sudan grass hybrid under different concentrations of NaCl. Non-inoculated maize and sorghum-sudangrass hybrid showed 33.4% and 20.0% reduction in seed germination under highest NaCl (150 mM) level tested. However, under the same NaCl concentration, co-inoculation with B. iodinum RS16 and M. oryzae CBMB20 PGP strains increased the seed germination in maize (16.7%) and sorghum-sudangrass hybrid (4.4%). In Gnotobiotic growth pouch experiments conducted for maize and sorghum-sudangrass hybrid, co-inoculation of PGP B. iodinum RS16 and M. oryzae CBMB20 mitigated the salinity stress and promoted root length by 22.9% and 29.7%, respectively. Thus the results of this study could help in development of potential bioinoculants that may be suitable for crop production under saline conditions.

• The Plant Pathology Journal
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• v.22 no.4
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• pp.348-352
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• 2006

Barley mild mosaic virus(BaMMV) is a soilborne Bymovirus vectored by root-infecting fungus, Polymyxa graminis. Mechanism of cultivar's resistance to BaMMV in field tests are difficult to assess since resistance could be either due to the virus or to P. graminis, or both. Whereas, available mechanical inoculation methods for BaMMV and other related viruses are labor intensive, give inconsistent results and generally result in low infection rates. Inoculation method using stick with gauze(SWG) was developed for BaMMV. The improved method proved to be simple, efficient, and reliable. The infected leaf tissues were preserved by drying in a frozen state under high vaccum(freeze dried barley infected leaves) to circumvent reduction of virus infectivity during storage. Five Korean barley cultivars were mechanically inoculated with BaMMV-infected sap by the improved method. Infection rates obtained were compared with natural infection. Cultivar Naehanssalbori showed resistance to BaMMV in the field trials but was found highly susceptible in the greenhouse tests by mechanical inoculation, indicating that the field resistance may be possibly due to resistance to P. graminis.