• Journal of Mushroom
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• v.16 no.1
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• pp.31-38
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• 2018

This study investigated the synergistic effect of single inoculation and co-inoculation of phosphate-solubilizing bacteria (PSB) Pantoea rodasil LH-1and Burkholderia stabilis HS-7. Phosphate-solubilizing abilities of these strains were assessed by measuring phosphorus content in culture media that were singly inoculated or co-inoculated with these strains for 7 days. The co-inoculation of P. rodasil LH-1and B. stabilis HS-7 was found to release the highest content of soluble phosphorus ($783.41{\mu}g\;mL^{-1}$) into the medium, followed by single inoculation of B. stabilis HS-7B ($743.90{\mu}g\;mL^{-1}$) and P. rodasil LH-1 ($736.59{\mu}g\;mL^{-1}$). The highest pH reduction, organic acid production, and glucose consumption were also observed in the medium inoculated with both the strains, compared with that in the medium inoculated with the strain alone. Results of a plant growth promotion bioassay showed 7.7% and 15.5% higher leaf and root growth, respectively, in romaine lettuce co-inoculated with P. rodasil LH-1and B. stabilis HS-7 than those inoculated with the strain alone. However, no significant difference was observed between single inoculation and co-inoculation of these strains with respect to phosphorus release and plant growth. Although the results of the present study did remarkdly not show the synergistic effect of phosphate solubilization by co-inoculation of the PSB strains examined, these results indicate that treatment with PSB exerts a beneficial effect on crop growth.

• Journal of Microbiology and Biotechnology
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• v.25 no.6
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• pp.903-909
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• 2015

Indole-3-acetic acid (IAA) production is a typical mechanism of plant growth promotion by some rhizobacteria. However, a functional genomic study is necessary to unravel the function and mechanism of IAA signaling during rhizobacteria-plant interactions. In this study, the expression of SlIAA1 and SlIAA9 among the auxin response genes in tomato was examined during the interaction between IAA-producing Acinetobacter guillouiae SW5 and tomato plants. When 3-day grown tomato seedlings were treated for 30 min with 10~100 µM of IAA produced by bacteria from tryptophan, the relative mRNA levels of SlIAA1 and SlIAA9 increased significantly compared with those of the control, demonstrating that IAA produced by this bacterium can induce the expressions of both genes. Inoculation of live A. guillouiae SW5 to tomato seedlings also increased the expressions of SlIAA1 and SlIAA9, with more mRNA produced at higher bacterial density. In contrast, treatment of tomato seedlings with dead A. guillouiae SW5 did not significantly affect the expression of SlIAA1and SlIAA9. When 3-day bacterial culture in tomato root exudates was administered to tomato seedlings, the relative mRNA level of SlIAA1 increased. This result indicated that the plant may take up IAA produced by bacteria in plant root exudates, which may increase the expression of the auxin response genes, with resulting promotion of plant growth.

• The Korean Journal of Mycology
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• v.33 no.2
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• pp.98-102
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• 2005

In 2003 to 2005, the root rot of Japanese angelica (Aralia elata) was surveyed in nursery beds of Korea, where incidence of the disease often reached up to 100%. Three isolates were obtained from the infected roots, and identified as Phytophthora cactorum on the basis of cultural, morphological characteristics and molecular analysis. The isolates were characterized by having markedly papillate and broadly ovoid deciduous sporangia. The optimum temperature for mycelium growth was at $25^{\circ}C$ on V8 juice agar. Pathogenicity of the isolates was confirmed by soil mixture inoculation. Approximately 900 bp of ITS rDNA was amplified from all 3 isolates and band pattern of restriction fragments observed by Alu I, Msp I, and Taq I digestion also supported the result of the morphological identification when compared with PhytID database.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.4
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• pp.401-408
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• 2016

The present study described the isolation of 2-methylbutyric acid (2-MBA) produced from Bacillus pumilus L1, to subsequently investigate its nematicidal activity for the control of the root-knot nematode. The results showed that 2-MBA could be purified by chromatographic techniques and was identified using nuclear magnetic resonance and liquid chromatography-mass spectrometry. Crude extract and partially purified compounds had a significant effect on the inhibition of egg hatchability and second-stage juvenile (J2) mortality. A dose-dependent effect of 2-MBA was observed for J2 mortality and egg hatchability. Egg hatchability was 69.2%, 59.9%, 32.7%, and 0.0% at 125, 250, 500, and $1000{\mu}g\;mL^{-1}$ of 2-MBA after 4 d of incubation, respectively. Meanwhile, J2 mortality was in the range of 24.4%-100.0% after 2 d of incubation, depending on the concentrations of 2-MBA used. A pot experiment also demonstrated that treatment of B. pumilus L1 culture caused a significant reduction in the number of galls, egg masses, and J2 population than that of the tap water (TW) control. However, as the B. pumilus L1 culture concentration was decreased, the efficacy of nematode control by treatment of B. pumilus L1 culture was reduced compared to that of TW. B. pumilus L1 inoculation at different concentrations also promoted cucumber plant growth. Therefore, our study demonstrated the potential of 2-MBA from B. pumilus L1 as a biocontrol agent against the root-knot nematode and a plant growth promoter for cucumber plants.

• The Plant Pathology Journal
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• v.21 no.1
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• pp.68-72
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• 2005

The production of antibiotic substances by Serratia plymuthica A21-4 was greatly enhanced by modifying components of a growth medium. When the minimal medium containing $K_2HPO_4$ 0.7%, $KH_2PO_4$ 0.2%, $(NH_4)_2SO_4$ 0.1%, $MgSO_4$ 0.01% was used as basal medium, the best carbon source for antibiotic production was glycerol and the most favorable nitrogen source was ammonium sulfate. The modified medium for antibiotic production also increased colonization ability of A21-4 on pepper root and in the rhizosphere soil. When the cells of A21-4 were suspended in modified medium, the population density of A21-4 on pepper root was 10-100 times higher than that suspended in 0.1 M $MgSO_4$. The population density of A21-4 on root did not decrease under $10^6$ cfu/groot up to 21 days after treatment although the inoculum of A21-4 was reduced to $10^7$ cell/ml. Similar tendency was also observed in the rhizosphere soil. Consequently, Phytophthora blight of pepper was successfully controlled by A21-4 with $10^7$ cell/ml suspended in the modified buffer solution instead of $10^9$ cfu/ml suspended in 0.1 M $MgSO_4$.

• Journal of Microbiology and Biotechnology
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• v.20 no.11
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• pp.1577-1584
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• 2010

In total, 140 halotolerant bacterial strains were isolated from both the soil of barren fields and the rhizosphere of six naturally growing halophytic plants in the vicinity of the Yellow Sea, near the city of Incheon in the Republic of Korea. All of these strains were characterized for multiple plant growth promoting traits, such as the production of indole acetic acid (IAA), nitrogen fixation, phosphorus (P) and zinc (Zn) solubilization, thiosulfate ($S_2O_3$) oxidation, the production of ammonia ($NH_3$), and the production of extracellular hydrolytic enzymes such as protease, chitinase, pectinase, cellulase, and lipase under in vitro conditions. From the original 140 strains tested, on the basis of the latter tests for plant growth promotional activity, 36 were selected for further examination. These 36 halotolerant bacterial strains were then tested for 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity. Twenty-five of these were found to be positive, and to be exhibiting significantly varying levels of activity. 16S rRNA gene sequencing analyses of the 36 halotolerant strains showed that they belong to 10 different bacterial genera: Bacillus, Brevibacterium, Planococcus, Zhihengliuella, Halomonas, Exiguobacterium, Oceanimonas, Corynebacterium, Arthrobacter, and Micrococcus. Inoculation of the 14 halotolerant bacterial strains to ameliorate salt stress (150 mM NaCl) in canola plants produced an increase in root length of between 5.2% and 47.8%, and dry weight of between 16.2% and 43%, in comparison with the uninoculated positive controls. In particular, three of the bacteria, Brevibacterium epidermidis RS15, Micrococcus yunnanensis RS222, and Bacillus aryabhattai RS341, all showed more than 40% increase in root elongation and dry weight when compared with uninoculated salt-stressed canola seedlings. These results indicate that certain halotolerant bacteria, isolated from coastal soils, have a real potential to enhance plant growth under saline stress, through the reduction of ethylene production via ACC deaminase activity.

• Journal of Korean Society of Forest Science
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• v.79 no.3
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• pp.322-329
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• 1990

A group of Pinus densiflora trees attacked by Rhizina root rot were observed at Kangnung. Diseased roots are characterized by rot patches, radial rot traces or formation of adhesive soil masses. The damage has proceeded about 6m per annum, and the pathogen in the infected soil was detected by trap logs. Ascospores of Rhizina undulata was germinated by heat shock at $37^{\circ}C$ for 24 hours or at $40^{\circ}C$ for 17 hours. The mycerial growth was optimum on PDA medium at $25-30^{\circ}C$and pH 5.6-6.3. Coniferous trees were more susceptible than non-coniferous trees in inoculation test in vitro.

• Research in Plant Disease
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• v.14 no.1
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• pp.64-67
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• 2008

In 2005 and 2007, petiole and root rot of Spathiphyllum spp. was occurred at commercial greenhouse during summer (June-September) in Koyang city and Yongin city, Kyunggi-do, Korea. The pathogenic fungus was isolated from diseased plants and the cultural and morphological chracteristic were observed. Conidia were rod in shape, 1-3 septa and $67.5-95.0{\times}4.8-6.5\;{\mu}m$ (av. $82.0{\times}6.0\;{\mu}m$) in size. The optimum temperature for the mycelial growth of the isolates was $27^{\circ}C$. According to result the pathogenicity test, first disease symptoms appeared five days after inoculation. On the basis of mycological characteristics and pathogenicity test on host plants, the fungus was identified as Cylindrocladium spathiphylli. This is the first report on Spathiphyllum spp. caused by C spathiphylli in Korea.

• The Plant Pathology Journal
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• v.35 no.3
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• pp.219-233
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• 2019

Soybean cultivars susceptible to Phytophthora root and stem rot are vulnerable to seed rot and damping-off of seedlings and young plants following an infection by Phytophthora sojae. In this study, the disease responses of Japanese soybean cultivars including currently grown main cultivars during the early growth stages were investigated following infections by multiple P. sojae isolates from Japanese fields. The extent of the resistance to 17 P. sojae isolates after inoculations at 14, 21, and 28 days after seeding varied significantly among 18 Japanese and two US soybean cultivars. Moreover, the disease responses of each cultivar differed significantly depending on the P. sojae isolate and the plant age at inoculation. Additionally, the treatment of 'Nattosyo-ryu' seeds with three fungicidal agrochemicals provided significant protection from P. sojae when plants were inoculated at 14-28 days after seeding. These results indicate that none of the Japanese soybean cultivars are completely resistant to all tested P. sojae isolates during the first month after sowing. However, the severity of the disease was limited when plants were inoculated during the later growth stages. Furthermore, the protective effects of the tested agrochemicals were maintained for at least 28 days after the seed treatment. Japanese soybean cultivars susceptible to Phytophthora root and stem rot that are grown under environmental conditions favorable for P. sojae infections require the implementation of certain practices, such as seed treatments with appropriate agrochemicals, to ensure they are protected from P. sojae during the early part of the soybean growing season.

• The Korea Journal of Herbology
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• v.24 no.3
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• pp.13-19
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• 2009

Objectives : This study was aimed to define the protective effect of Tissue Cultured Root of Wild Ginseng (CWG) against doxorubicin (Doxo) toxicity, and investigate the anti-tumor synergic effect of CWG in combination with Doxo in tumor-bearing C57BL/6 mice. Methods : Tumor-bearing mice were established by single inoculation with B16/F10 melanoma cells (2$\times$10$^6$/ml) subcutaneously. Tumor-bearing mice (tumor volume between 50-100 mm$^3$) were selected and divided them into control, Doxo, and Doxo+CWG group. Mice of Doxo group were received with Doxo (4 mg/kg of B.W.) intraperitoneally at 0, 4, 8 days after starting the experiment. Mice of Doxo+CWG group were received CWG water extract during 12 days in combination with Doxo treatment. The body weight, tumor volume, tumor weight, and organ weight (heart, liver, kidney, and testis) were measured. And serum SPK, GOT and creatinine values were analysed. Results : The volume and weights of tumor masses in Doxo group were decreased significantly compared with the those of control group. And the those of Doxo+CWG group were not significantly different from the those of Doxo group. Whereas the weight of body, liver, kidney and testis in Doxo+CWG group were increased significantly compared with the those of Doxo group. The level of serum CPK and GOT in Doxo group were increased compared with the those of control group. But the value of Doxo+CWG group were decreased significantly compared with the values of Doxo group. Conclusions : These results suggest that CWG has protective effect against doxorubicin toxicity. And these effect is guessed that is caused in augmentation of vital energy.