• Korean Journal of Soil Science and Fertilizer
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• v.22 no.3
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• pp.245-252
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• 1989

This experiment was carried out to study the effects of nitrogen concentration of cultural solution, rhizobium inoculation, and planting density on nodulation, contents of total-N and allantoin-N of the plants, and contents of crude fat and protein of the seeds with 4 cultivars and 1 non-nodulation isogenic line (Hwangeumkong, Jangbaegkong, Paldalkong, Clark, non-nodulating Clark) in nutri-culture. Modulation was increased significantly by the rhizobium inoculation and decreased by the increase of nitrogen concentration of the cultural solution and planting density, and more nodule per plant was observed in Hwangeumkong than other cultivars. Total nitrogen contents of the soybean plant were higher in Hwangeumkong and Janbaegkong compared with other two cultivars, and were increased by rhizobium inoculation and the increase of nitrogen concentration of the cultural solution except in case of $R_3$ stage of non-inoculation of rhizobium, and was decreased by the increase of planting density. Allantoin nitrogen contents of stem were lower in Paldalkong compared with other cultivars and was increased significantly by the rhizobium inoculation, and thus was correlated significantly with nodulation. Allantoin-N contents were also decreased by the increase of planting density and nitrogen concentration of the solution, and was very low in case of non-nodulating isogenic line at any level of nitrogen concentration. The contents of crude fat of the seed were lower in cases of higher nitrogen concentration of the solution and more plants per pot, but no effects of rhizobium inoculation was observed. The contents of crude protein were tend to increase by the increase of nitrogen concentration, but were little effected by rhizobium inoculation and planting density.

• Journal of Korean Society of Forest Science
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• v.94 no.6
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• pp.402-409
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• 2005

This study was undertaken to compare and estimate the severity of pitch canker of individual trees of Pinus rigida and Pinus rigida ${\times}$ P. taeda in two seed orchards in Jeju island, in which the orchards have been damaged by the pitch canker for seven years. Wind-pollinated two-year-old seedlings of P. rigida and P. rigida ${\times}$ P. taeda, in which the seedlings of P. rigida ${\times}$ P. taeda were from seeds of phenotypically selected, uninfected(but untested) trees, were inoculated with the pathogenic fungus, Fusarium circinatum, isolated from P. rigida and P. thunbergii. The virulence of the isolates was also identified. Statistically significant difference was found in 'stem cankers'(SC; ${\chi}^2=7.76$, P=0.05) among 4 plantations of P. rigida ${\times}$ P. taeda of two seed orchards. P. rigida was higher in 'top kill' (TK) and 'branch tip symptoms' (BT) than those of P. rigida ${\times}$ P. taeda. In artificial inoculation tests, mortality of the seedlings from the resistant candidates was 14% higher than that of the seedlings from the susceptible candidates. This result may becaused by unknown pollen trees and/or candidate tree selection based only on phenotype. Two of five fungal isolates, C-6-L(9) and C-6-L(19), showed significantly higher mortality (68% and 60%, respectively) than others, suggesting that these isolates can be used as virulent isolates for a mass artificial inoculation. Resistance candidate seedlings that were selected from this study can be utilized as useful materials for fundamental studies of genetics and biochemistry to breed resistance varieties to pitch canker.

• 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.

• 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.

• The Plant Pathology Journal
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• v.24 no.1
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• pp.67-73
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• 2008

Seedling damping-off and bottom rot caused by Rhizoctonia solani are yield limiting diseases of crisphead lettuce. To provide biocontrol measure in the management of the diseases, biocontrol strain Pseudomonas aeruginosa LY-11 was isolated from lettuce rhizosphere and introduced into crisphead lettuce rhizosphere by the seed coating delivery method. Alginate was used as a coating material to generate beads containing $10^6-10^{6.5}$ colony-forming units (CFUs) of viable bacterial cells of LY-11. When seeds germinated from the alginate beads containing the strain LY-11, the bacteria established mostly in plant rhizosphere to maintain at least $10^4$ CFU per gram of plant tissues. Crisphead lettuce seedlings germinated from the entrapped seeds were less affected from damping-off and bottom rot with disease control values of 70.4% and 85.4% respectively. Although P. aeruginosa LY-11 colonized plant rhizosphere and not phyllosphere, the result indicated that bottom rot caused by the foliar inoculation of R. solani was effectively reduced by the rhizobacteria. All data suggested that immobilized rhizobacterial application in seeds by alginate coating could control damping-off and induce induced systemic resistance of crisphead lettuce to reduce bottom rot.

• Journal of Microbiology and Biotechnology
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• v.34 no.9
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• pp.1857-1866
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• 2024

Endophytic fungi have been shown to synthesize bioactive secondary metabolites, some of which promote plant growth through various mechanisms. In our previous study, endophytic fungi were isolated from mango trees (Mangifera indica L.). The present study examined fifty endophytic fungal isolates for mineral solubilization activity, ammonia production, and siderophore production. It was shown that these isolates could produce phytohormones indole-3-acetic acid and gibberellic acid, as well as inhibit plant pathogens, specifically Colletotrichum gloeosporioides and Lasiodiplodia theobromae. The results showed that all the isolated fungal endophytes exhibited various activities. Based on the findings, two fungal endophytes-Aureobasidium pullulans CY.OS 13 and Aspergillus tamarii CY.OS 144-were selected for dual inoculation in chili plants under pot-scale conditions to investigate their potential to improve growth-related traits such as seed germination, shoot and root length, biomass, and chlorophyll content. Seed treated with A. pullulans CY.OS 13 and/or A. tamarii CY.OS 144 showed a significant (p < 0.05) increase in seed germination and growth parameters of chili plants grown under pot-scale conditions. Particularly, chili plants whose seeds were injected with a combination of the two selected endophytic fungi showed the highest plant development traits. Therefore, the selected endophytic fungi have the potential to be used as biofertilizers, especially when combined. They could eventually replace chemical fertilizers because they are environmentally friendly, beneficial to humans, and can even promote sustainable agriculture.

• Journal of Korean Society of Forest Science
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• v.99 no.6
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• pp.871-877
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• 2010

This study was conducted to investigate the effects of host tree species, temperature and humidity on ex vitro for seed germination in endangered species of Loranthus tanakae. In addition, we compared seed shapes between Loranthus tanakae and Viscum album that we could have easily shown in ex vitro condition. Seeds were germinated after one week inoculation and followed to develop radicles. Seed germination rates of Loranthus tanakae were 80~95% in most of the experimental conditions. The highest rate of holdfast penetrated to host plants was 72% in Populus alba var. pyramidalis among 13 different species tested at $20^{\circ}C$. Also the rates of their penetration were 57% in Morus bombycis, 55% in Acer palmatum and 42% in Castanea crenata at $20^{\circ}C$. Seeds were germinated under condition without irrigation and followed to withered in 12 weeks later. Stages of seed germination of the Loranthus tanakae were followed by radicle induction, holdfast development, haustorium formation and penetration in order in total period of 14 weeks.

• The Plant Pathology Journal
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• v.31 no.4
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• pp.334-342
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• 2015

Two fumonisin-nonproducing strains of Fusarium verticillioides and their fumonisin producing progenitors were tested for aggressiveness toward maize, sorghum, rice, and beetroot seedlings grown under greenhouse conditions. None of the plants showed obvious disease symptoms after root dip inoculation. Fungal biomass was determined by species-specific real-time PCR. No significant (P = 0.05) differences in systemic colonization were detected between the wild type strains and mutants not producing fumonisins. F. verticillioides was not detected in any of the non-inoculated control plants. The fungus grew from roots to the first two internodes/leaves of maize, rice and beet regardless of fumonisin production. The systemic growth of F. verticillioides in sorghum was limited. The results showed that fumonisin production was not required for the infection of roots of maize, rice and beet by F. verticillioides.

• Mycobiology
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• v.32 no.4
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• pp.186-189
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• 2004

The study on the cultural characteristics of Bipolaris spicifera was conducted to provide with information for the identification, and inoculation studies, etc. B. spicifera grew well at $30{\sim}35^{\circ}C$ and wide range of pH $5.0{\sim}9.0$. However, the fungal growth was retarded at pH 4.0 and 10.0, respectively. Conidia were germinated with 70% at $30^{\circ}C$ but maintained 50% germination even at $40^{\circ}C$, indicating that this pathogen could infect plants at relatively high temperature. The pathogen could not produce conidia under 24 hr fluorescent light condition for 7 days. In contrast, it produced many more conidia at 24 hr dark condition.

• The Plant Pathology Journal
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• v.37 no.6
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• pp.673-680
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• 2021

Acidovorax citrulli (Ac) is the causative agent of bacterial fruit blotch disease in watermelon. Since resistant cultivars have not yet been developed, the virulence factors/mechanisms of Ac need to be characterized. This study reports the functions of a putative pyridoxal phosphate-dependent aminotransferase (PpdaAc) that transfers amino groups to its substrates and uses pyridoxal phosphate as a coenzyme. It was observed that a ppdaAc knockout mutant had a significantly reduced virulence in watermelon when introduced via germinated-seed inoculation as well as leaf infiltration. Comparative proteomic analysis predicted the cellular mechanisms related to PpdaAc. Apart from causing virulence, the PpdaAc may have significant roles in energy production, cell membrane, motility, chemotaxis, post-translational modifications, and iron-related mechanisms. Therefore, it is postulated that PpdaAc may possess pleiotropic effects. These results provide new insights into the functions of a previously unidentified PpdaAc in Ac.