• Korean Journal of Environmental Agriculture
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• v.30 no.4
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• pp.395-401
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• 2011

BACKGROUND: Potassium (K) is one of the macronutrients which are essential for plant growth and development. Its deficiency in paddy soils is becoming one of the limiting factors for increasing rice yield in Asia. METHODS AND RESULTS: To investigate physiological symptoms under K-starvation (NP) compared with complete media (NPK) condition, we measured shoot/root length, weight, nutrients, and patterns of protein expression. The shoot growth was significantly reduced, but root growth was not affected by K-starvation. However, biomasses were decreased in both shoot and root. Uptake of K was reduced up to 85%, while total concentrations of P, Ca, Mg, Na were increased in root and shoot. To better understand the starved K mechanism of rice, comparative proteome analysis for proteins isolated from rice leaves was conducted using 2-DGE. Five spots of differentially expressed proteins were analyzed by MALDI-TOF MS. Analysis of these K-starvation response proteins suggested that they were involved in metabolism and defense. CONCLUSION(s): Physiological and 2-DGE based proteomics approach used in our study results in observation of morphology or nutrients change and identification of K-starvation responsive proteins in rice root. These results have important roles in maintaining nutrient homeostasis and would also be useful for further characterization of protein function in plant K nutrition.

• The Plant Pathology Journal
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• v.25 no.3
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• pp.256-262
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• 2009

The potential of. nonpathogenic Fusarium oxysporum strain Avr5, either alone or in combination with chitosan and Bion, for inducing defense reaction in tomato plants inoculated with F. oxysporum f. sp lycopersici, was studied in vitro and glasshouse conditions. Application Bion at concentration of 5, 50, 100 and $500{\mu}g$/ml, and the highest concentration of chitosan reduced in vitro growth of the pathogen. Nonpathogenic F. oxysporum Avr5 reduced the disease severity of Fusarium wilt of tomato in split plants, significantly. Bion and chitosan applied on tomato seedlings at concentration $100{\mu}g$ a.i./plant; 15, 10 and 5 days before inoculation of pathogen. All treatments significantly reduced disease severity of Fusarium wilt of tomato relative to the infected control. The biggest disease reduction and increasing tomato growth belong to combination of nonpathogenic Fusarium and Bion. Growth rate of shoot and root markedly inhibited in tomato plants in response to tomato Fusarium wilt as compared with healthy control. These results suggest that reduction in disease incidence and promotion in growth parameters in tomato plants inoculated with nonpathogenic Fusarium and sprayed with elicitors could be related to the synergistic and cooperative effect between them, which lead to the induction and regulation of disease resistance. Combination of elicitors and non-pathogenic Fusarium synergistically inhibit the growth of pathogen and provide the first experimental support to the hypothesis that such synergy can contribute to enhanced fungal resistance in tomato. This chemical could provide a new approach for suppression of tomato Fusarium wilt, but its practical use needs further investigation.

• The Plant Pathology Journal
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• v.29 no.4
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• pp.471-476
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• 2013

Plants are frequently exposed to numerous environmental stresses such as dehydration and high salinity, and have developed elaborate mechanisms to counteract the deleterious effects of stress. The phytohormone abscisic acid (ABA) plays a critical role as an integrator of plant responses to water-limited condition to activate ABA signal transduction pathway. Although perception of ABA has been suggested to be important, the function of each ABA receptor remains elusive in dehydration condition. Here, we show that ABA receptor, pyrabactin resistance-like protein 8 (PYL8), functions in dehydration conditions. Transgenic plants overexpressing PYL8 exhibited hypersensitive phenotype to ABA in seed germination, seedling growth and establishment. We found that hypersensitivity to ABA of transgenic plants results in high degrees of stomatal closure in response to ABA leading to low transpiration rates and ultimately more vulnerable to drought than the wild-type plants. In addition, high expression of ABA maker genes also contributes to altered drought tolerance phenotype. Overall, this work emphasizes the importance of ABA signaling by ABA receptor in stomata during defense response to drought stress.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.12
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• pp.1761-1767
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• 2015

This paper deals with the solar tracking performance using a small heliostat, the light reduction rate of the sun light, and the performance of uniform irradiation of LED light for a plant factory. A high precision encoder is attached to the heliostat to improve tracking accuracy. As a result, our heliostat-based solar tracking systems track efficiently the movement of the sun light in experimental tests. The reduction rate of the sun light in the plant factory is then measured by using an illumination sensor. The average reduction rate is 4.29%, which represents lower light reduction rates. In uniform irradiation tests of LED light, sixteen points are measured, and overall deviations of irradiation were within eight percents.

• The Plant Pathology Journal
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• v.21 no.4
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• pp.395-401
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• 2005

The dlm (disease lesion mimic) mutant of soybean (Glycine max L. Merr) shows the similar lesion of a soybean disease caused by a fungus, Corynespora cassilcola. The lesion was examined at cellular and molecular level. Trypan blue staining result indicated that cell death was detectable in the entire region of leaves excluding veins when the lesions had already been developed. We found that the mesophyll cells of palisade layer in the dim mutant appeared to be wider apart from each other. The chloroplasts of the dim mutant cells contained bigger starch granules than those in normal plants. We also found that the lesion development of dlm plant was light-dependent and the starch degradation during the dark period of diurnal cycle was impaired in the mutant. Three soybean pathogenesis-related genes, PR-1a, PR-4, and PR-10, were examined for their expression patterns during the development of disease lesion mimic. The expression of all three genes was up-regulated to some extent upon the appearance of the disease lesion mimic. Although the exact function of DLM protein remains elusive, our data would provide some insight into mechanism underling the cell death associated with the dim mutation.

• The Plant Pathology Journal
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• v.38 no.5
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• pp.432-448
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• 2022

Planthopper infestation in rice causes direct and indirect damage through feeding and viral transmission. Host microbes and small RNAs (sRNAs) play essential roles in regulating biological processes, such as metabolism, development, immunity, and stress responses in eukaryotic organisms, including plants and insects. Recently, advanced metagenomic approaches have facilitated investigations on microbial diversity and its function in insects and plants, highlighting the significance of microbiota in sustaining host life and regulating their interactions with the environment. Recent research has also suggested significant roles for sRNA-regulated genes during rice-planthopper interactions. The response and behavior of the rice plant to planthopper feeding are determined by changes in the host transcriptome, which might be regulated by sRNAs. In addition, the roles of microbial symbionts and sRNAs in the host response to viral infection are complex and involve defense-related changes in the host transcriptomic profile. This review reviews the structure and potential functions of microbes and sRNAs in rice and the associated planthopper species. In addition, the involvement of the microbiota and sRNAs in the rice-planthopper-virus interactions during planthopper infestation and viral infection are discussed.

• Journal of Plant Biotechnology
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• v.50
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• pp.76-81
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• 2023

As cultured plant cells can grow in high oxidative stress conditions, they form an excellent system to study antioxidant mechanisms and the mass production of antioxidants. Oxidative stress is a major cause of damage in plants exposed to various types of environmental stress, including heavy metals, such as cadmium (Cd). Heavy metal accumulation can interfere with many cell functions and plant growth. To evaluate the contribution of oxidative stress to Cd-induced toxicity, cultured sweetpotato (Ipomoea batatas) cells were treated with increasing concentrations of Cd (0, 10, 25, and 50 μM) and cultured further. Cell growth was significantly inhibited by 25 and 50 μM of Cd, and the total protein content increased with 50 μM of Cd. Additionally, the activity of peroxidase (POD) and ascorbate peroxidase (APX), antioxidant enzymes that remove hydrogen peroxide (a reactive oxygen species), increased in the cells after treatment with 50 μM of Cd. The expression analysis of POD, APX, and peroxiredoxin (PRX) isolated from sweetpotato cultured cells in a previous study revealed the differential expression of POD in response to Cd. In this study, the expression levels of several acidic POD (swpa2, swpa3, and swpa4) and basal POD (swpb1, swpb2, and swpb3) genes were increased in Cd-treated cultured cells. These results indicate that Cd-mediated oxidative stress is closely linked to improved POD-mediated antioxidant defense capacity in sweetpotato suspension-cultured cells.

• Korean Journal of Plant Resources
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• v.20 no.2
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• pp.216-219
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• 2007

Root colonization by a rhizobacterium, Pseudomonas chlororaphis O6, elicited induced systemic resistance (ISR) in the leaves of cucumber plants against fungal and bacterial pathogens. To understand the role of unique genes during strain O6-mediated ISR, a suppressive subtractive hybridization method was undertaken and led to isolation of twenty-five distinct genes. The transcriptional levels of all the genes showed an increase much earlier under O6 treatment than in water control plants only after challenge with pathogen, while no difference detected on the plants without pathogen challenge. This suggests that O6-mediated ISR is associated with the priming phenomenon, an enhanced capacity for the rapid and effective activation of cellular defense responses after challenge inoculation.

• The Plant Pathology Journal
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• v.32 no.3
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• pp.228-241
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• 2016

In our previous study, we reported that a novel endophytic bacterium Bacillus oryzicola YC7007 has suppressed bacterial diseases of rice via induced systemic resistance and antibiotic production. This endophytic strain, B. oryzicola YC7007 was used as a biological control agent against bakanae disease of rice caused by Fusarium fujikuroi, and its mechanism of interaction with the pathogen and the rice was further elucidated. Root drenching with B. oryzicola YC7007 suspension reduced the disease severity of bakanae significantly when compared with the untreated controls. The treatments of B. oryzicola YC7007 suspension ($2.0{\times}10^7cfu/ml$) to the rice rhizosphere reduced bakanae severity by 46-78% in pots and nursery box tests containing autoclaved and non-autoclaved soils. Moreover, in the detached rice leaves bioassay, the development of necrotic lesion and mycelial expansion of F. fujikuroi were inhibited significantly by spraying the culture filtrate of B. oryzicola YC7007. Drenching of ethyl acetate extracts of the culture filtrate to the rhizosphere of rice seedlings also reduced the bakanae disease severity in the plant culture dish tests. With the root drenching of B. oryzicola YC7007 suspension, the accumulation of hydrogen peroxide was observed at an early stage of rice seedlings, and a hormonal defense was elicited with and without pathogen inoculation. Our results showed that the strain B. oryzicola YC7007 had a good biocontrol activity against the bakanae disease of rice by direct inhibition, and was also capable of inducing systemic resistance against the pathogen via primed induction of the jasmonic acid pathway.

• Journal of the Korean Applied Science and Technology
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• v.35 no.3
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• pp.865-875
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• 2018

Selection of optimum reaction conditions during deoxygenation process of palm oil is essential factor to obtain the maximum yield of bio-jet fuel. In this context, the deoxygenation of palm oil was carried out in a fixed bed reactor with an internal diameter of 1 inch loaded with a 1 wt.% $Pt/Al_2O_3$ catalyst. The composition of the organic liquid product(OLP), which can be utilized as a transportation fuel through the upgrading process, was analyzed by a gas chromatography method. The palm oil/hydrogen ratio and hydrogen pressure in the feed affected the decarboxylation(DCB) and hydrodeoxygenation(HDO) reactions, resulting in a change in the composition of the OLP. As the reaction temperature increased, the continuous cracking reaction of the deoxygenation product was promoted and the product composition in the $C_5{\sim}C_{14}$ region was increased. Thus, the results can help to understand the characteristics of deoxidation reaction of palm oil as well as the subsequent process, hydro-upgrading, to obtain the maximum yield of bio-jet fuel.