• Journal of Sericultural and Entomological Science
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• v.18 no.2
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• pp.83-88
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• 1976

A study was made on the interstrain difference in dose-infection response and induction response of silkworm to the two strains of cytoplasmic polyhedrosis virus to obtain some informations on screening the leading strains. Comparison of dose-infection responses of larvae following the inoculation of the inclusion body of cytoplasmic polyhedrosis virus revealed that there is no significance in the resistance to dose-infection and any of strains were more resistant at advanced stage(4th instar) than younger stage(2nd instar). In the pathogenicity between cytoplasmic polyhedrosis virus with hexagonal and tetragonal outline, the hexagonal polyhedra showed higher pathogenicity than the tetragonal polyhedra. However, the averages of $LC_{50}$ of cytoplasmic polyhedrosis virus with hexagonal outline to larvae of parental inbred line were 6.12${\times}$10$\^$6//$m\ell$ at 2nd instar and 1.57${\times}$10$\^$7//$m\ell$ at 4th instar in spring and those to their hybrids were 1.28${\times}$10$\^$6//$m\ell$ at 2nd ins tar and 4.99${\times}$10$\^$6//$m\ell$ at 4th ins tar in autumn. Meanwhile the $LC_{50}$ averages of tetragonal polyhedra. to larvae of parental inbred line were 2.06${\times}$10$\^$7//$m\ell$ at 2nd instar and 5.67${\times}$10$\^$7//$m\ell$ at 4th instar in spring and those to their hybrids were 9.84${\times}$10$\^$6//$m\ell$ at 2nd instar and 3.86${\times}$10$\^$7//$m\ell$ at 4th instar in autumn, respectively. In comparison of induction response of silkworm larvae to inoculation of tetragonal polyhedra of cytoplasmic polyhedrosis virus, the induction rate of hexagonal polyhedra was remarkably higher in the treatment of inoculation at 2nd instar than at 4th instar and at the concentration of 1.3${\times}$10$\^$6//$m\ell$ than at any others. Most of induction showed a mixed infection with hexagonal and tetragonal polyhedra of cytoplasmic polyhedrosis virus.

• Korean Journal of Agricultural Science
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• v.6 no.2
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• pp.105-111
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• 1979

This experiment was carried out to define the affinity of alfalfa varieties to nodule bacteria and the effects of nodule bacteria on the growth of alfalfa varieties. The results obtained are summarized as follows; 1. The ability of nodule formation on the roots of alfalfa was significantly different among the strains of nodule bacteria, Rhizobium meliloti SU 47 formed nodules on the roots of two alfalfa varieties, Luna and Von arnims altd bost. Nodules were not formed at the roots of all varieties by inoculation of Rhizobium meliloti M1 but a lot of nodules were formed at the roots of all varieties by inoculation of Rhizobium meliloti M14. 2. When the Rhizobium meliloti M14 was inoculated in the media, the largest numbers of nodules were formed on the roots of alfalfa cultivar Franks hangmeiler and the least numbers of nodules were formed on the roots of cultivar Elga. 3. The plant height and the dry matter weight of all alfalfa cultivars were significantly increased by inoculation of Rhizobium meliloti M14, and also those were increased by applying nitrogen, but when the alfalfa cultivars were grown on the media inoculated Rhizobium M1, the plant height and the dry matter weight of alfalfas were not increased and they were same as those grown on check media. 4. The significant correlation were not detected between the number of nodules formed on the, roots of alfalfa cultivars and the plant height or the dry matter weight of alfalfa cultivars.

• Korean Journal of Veterinary Research
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• v.46 no.4
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• pp.327-335
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• 2006

A stable and reliable Helicobacter pylori (H. pylori) infection animal model would be necessary for evaluating vaccine efficacy and helpful for understanding the pathological mechanism of the organism. The aim of the present study is to investigate the effect of ethanol treatment prior to H. pylori inoculation on associated gastric mucosal injury and to establish ethanol-pretreating animal model to study H. pylori infection. Male Mongolian gerbils were used for the study. H. pylori was orally inoculated after 12 h fasting. 3 h prior to H. pylori inoculation, a group of gerbils was orally treated with absolute ethanol, 60% and 40% ethanol respectively. Another group of animals was treated either with H. pylori culture media alone or with different concentrations of ethanol plus culture media. Gerbils were killed 4 or 8 weeks after H. pylori inoculation. The colonization of H. pylori was confirmed by both histological examination and rapid urease test. Mucosal damage was evaluated grossly and histologically according to the criteria. The colonization of H. pylori and pathological changes in gastric mucosa of the animals were also observed. Although no significant change to the gastric mucose was observed in the animals treated either with H. pylori culture media alone or with different concentrations of ethanol plus culture media, persistent H. pylori infection was seen in the mucosa and mucosal leucocyte infiltration and severe epithelial damage was observed in the Helicobacter and ethanol + Helicobacter groups after 4 weeks. The gross and histological scores were higher in the ethanol + Helicobacter than in the Helicobacter alone group. As the results, ethanol-pretreatment with 60% concentration induced severe pathogenic changes by H. pylori infection in 5 weeks-old Mongolian gerbils. These results suggested that ethanol-pretreatment before H. pylori inoculation could increase the severity of gastric mucosal inflammation and enhance the colonization of H. pylori. The established ethanol-pretreating animal model would contribute to screen new drugs against H. pylori and be used as an useful tool for various animal experiments with H. pylori strains.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.10
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• pp.1390-1394
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• 2004

We have achieved efficient transformation system for forage-type tall fescue plants by Agrobacterium tumefaciens. Mature seed-derived embryogenic calli were infected and co-cultivated with each of three A. tumefaciens strains, all of which harbored a standard binary vector pIG121Hm encoding the neomycin phosphotransferase II (NPTII), hygromycin phosphotransferase (HPT) and intron-containing $\beta$-glucuronidase (intron-GUS) genes in the T-DNA region. Transformation efficiency was influenced by the A. tumefaciens strain, addition of the phenolic compound acetosyringone and duration of vacuum treatment. Of the three A. tumefaciens strains tested, EHA101/pIG121Hm was found to be most effective followed by GV3101/pIG121Hm and LBA4404/pIG121Hm for transient GUS expression after 3 days co-cultivation. Inclusion of 100 $\mu$M acetosyringone in both the inoculation and co-cultivation media lead to an improvement in transient GUS expression observed in targeted calli. Vacuum treatment during infection of calli with A. tumefaciens strains increased transformation efficiency. The highest stable transformation efficiency of transgenic plants was obtained when mature seed-derived calli infected with A. tumefaciens EHA101/pIG121Hm in the presence of 100 $\mu$M acetosyringone and vacuum treatment for 30 min. Southern blot analysis indicated integration of the transgene into the genome of tall fescue. The transformation system developed in this study would be useful for Agrobacterium-mediated genetic transformation of tall fescue plants with genes of agronomic importance.

• Research in Plant Disease
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• v.10 no.1
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• pp.63-68
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• 2004

Twenty-three strains of Serratia sp., isolated from surface-sterilized rice roots collected in Chonbuk and Chungnam province, were identified and characterized. They were Gram-negative, rod shaped and red pigmented typically and their endophytism was confirmed by inoculation and reisolation of the strains in planta. Their antifungal activity against 4 rice pathogenic fungi was compared and ranged from 62.4 to 85.2％ against Rhizoctonia solani and 68.0 to 88.5％ against Pyricularia grisea. Among the 23 strains tested, strain Rsm220 showed the strongest inhibition activity against 4 pathogenic fungi. The strain was, therefore, selected as a biocontrol candidate for both the pathogens and its bacteriological characteristics and 165 rDNA sequences were analyzed. Phenotypic and biochemical characteristics of the selected Rsm220 were highly related to the type strain of S. marcescens and 165 rDNA sequencing of Rsm220 showed a homology of 98.2％ to the type strain of S. marcescens. The strain Rsm220 was identified as S. marcescens and the inhibition result of this endophytic strain indicates that it is a potential biocontrol agent for R. solani and R grisea.

• Journal of Korean Society of Forest Science
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• v.87 no.2
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• pp.253-259
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• 1998

The stimulated secretion of golden varnish sap by the infection of microorganisms on the bark of Dendropanax morbifera Lev. was observed in the natural habitats. Four candidate strains of such microorganisms(i.e., Sb1, Sb2, Sb3 and Sb4) were isolated from the bark of D. morbifera which was infected in natural. Of them, Sb3 and Sb4 strains showed stimulated secretion of golden vernish sap with the greatest stimulation by Sb4 strains. The yield of golden varnish sap from the bark of D. morbifera was boosted about 3.4~7.7 times by the inoculation of Sb4 strain in compassion with that collected from lacquer tree(Rhus verniciflua Stokes) by the traditional method. The mycelium color of Sb4 strain was grayish white. The optimum growth temperatures and pH were ranged from 30 to $35^{\circ}C$ and from pH 6.5 to 7.0.

• The Plant Pathology Journal
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• v.31 no.1
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• pp.25-32
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• 2015

Pseudomonas coronafaciens causes halo blight on oats and is a plant quarantine bacterium in many countries, including the Republic of Korea. Using of the certificated seed is important for control of the disease. Since effective detection method of P. coronafaciens is not available yet, PCR and TaqMan PCR assays for specific detection of P. coronafaciens were developed in this study. PCR primers were designed from the draft genome sequence of P. coronafaciens LMG 5060 which was obtained by the next-generation sequencing in this study. The PCR primer set Pc-12-F/Pc-12-R specifically amplified 498 bp from the 13 strains of P. coronafaciens isolated in the seven different countries (Canada, Japan, United Kingdom, Zimbabwe, Kenya, Germany, and New Zealand) and the nested primer set Pc-12-ne-F/Pc-12-ne-R specifically amplified 298 bp from those strains. The target-size PCR product was not amplified from the non-target bacteria with the PCR and nested primer sets. TaqMan PCR with Pc-12-ne-F/Pc-12-ne-R and a TaqMan probe, Pc-taqman, which were designed inside of the nested PCR amplicon, generated Ct values which in a dose-dependent manner to the amount of the target DNA and the Ct values of all the P. coronafaciens strains were above the threshold Ct value for positive detection. The TaqMan PCR generated positive Ct values from the seed extracts of the artificially inoculated oat seeds above 10 cfu/ml inoculation level. PCR and TaqMan PCR assays developed in this study will be useful tools to detect and identify the plant quarantine pathogen, P. coronafaciens.

• Research in Plant Disease
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• v.29 no.4
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• pp.433-439
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• 2023

Bacterial leaf blight in carrot is one of the most important diseases in the worldwide. In the past decade, its introduction into Korea is causing great concern due to the potential damage to carrot crops domestically. This bacterial disease is caused by Xanthomonas hortorum pv. carotae (Xhc). This study aimed to isolate and identify bacterial strains from the soil of carrot farms in Jeju Island. The bacterial isolates showing characteristics similar with those of Xhc were selected when cultured on artificial media. Through DNA sequencing and analysis based on NCBI data, some of the selected bacterial strains were identified as Xhc. Furthermore, the bacterial strains caused the typical symptom of bacterial leaf blight after inoculation on carrot leaves. The results of this study showed the potential establishment of Xhc in the soil of Jeju Island and it may be valuable data for establish a strategy preventing the domestic spread of carrot bacterial leaf blight in the future.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.4
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• pp.345-350
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• 1986

In order to select suitable strains for utilization as soybean inoculants, the affinity between Rhizobium japonicum strains isolated from the domestic field and the several soybean varieties being distributed as recommended species was investigated by cross-inoculation experiments. The results obtained are as follows: 1. Rhizobium japonicum R-214 and R-138 showed broad affinity range to varies soybean species in terms of the nodule forming ability, the nitrogen fixing activity and the amount of total nitrogen absorption. In contrast, Rhizobium japonicum R-224 showed very low affinity to the same soybean groups. 2. The affinity of Hwang-Keum Kong and Jang-Paeck Kong to the rhizobium strains was the most signigicant, and that of Jang-Yeop Kong, Dong-Buk Tae, Paeck-Woon Kong and Dan-Yeop Kong was also significant. On the other hand, Pang-Sa Kong showed low affinity to the strains. 3. In general, the strains having high nitrogen-fixing activity seemed to possess the broad affinity range to the soybean hosts.

• Research in Plant Disease
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• v.22 no.1
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• pp.1-8
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• 2016

Elsinoe fawcettii causing citrus scab was suppressed by rhizobacterial strains such as Burkholderia gladioli MRL408-3, TRH423-3 and Pseudomonas fluorescens THJ609-3, TRH415-2 having antifungal activity. The leaf surface of Satsuma mandarin, which was pre-treated with the rhizobacterial strains, was observed by a scanning electron microscope (SEM) after inoculation with E. fawcettii. The number of lesions was reduced on the leaves pre-treated with the rhizobacterial strains compared to those of untreated leaves. Especially, the lesions numbers was apparently reduced on the leaves pre-treated with B. gladioli MRL408-3. The observation by SEM revealed that not only the germination rate but also the length of germ tube of the pathogen were decreased on the rhizobacterial strains pre-treated leaves. These inhibition of the fungal growth was more strongly expressed on the leaves pre-treated with commercial fungicide imibenconazole, by which the lesions was rarely found on the leaves. Based on these results, it was suggested that rhizobacterial strains may inhibit the germination and growth of the E. fawcettii on the surface of citrus leaves, resulting in decrease of disease severity.