• Nuclear Engineering and Technology
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• v.44 no.3
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• pp.343-354
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• 2012

Primary water stress corrosion cracking (PWSCC) is a major safety concern in the nuclear power industry worldwide. PWSCC is known to initiate only in the condition in which sufficiently high tensile stress is applied to alloy 600 tube material or alloy 82/182 weld material in pressurized water reactor operating environments. However, it is still uncertain how much tensile stress is re-quired to generate PWSCC or what causes such high tensile stress. This study was performed to pre-dict the magnitude of weld residual stress and operating stress and compare it with previous experi-mental results for PWSCC initiation. For the study, a pressurizer safety nozzle was selected because it is reported to be vulnerable to PWSCC in overseas plants. The assessment was conducted by nu-merical analysis. Before performing stress analysis for plant conditions, a preliminary mock-up ana-lysis was done. The result of the preliminary analysis was validated by residual stress measurement in the mock-up. After verification of the analysis methodology, an analysis under plant conditions was conducted. The analysis results show that the stress level is not high enough to initiate PWSCC. If a plant is properly welded and operated, PWSCC is not likely to occur in the pressurizer safety nozzle.

• The Plant Pathology Journal
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• v.17 no.2
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• pp.88-93
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• 2001

Oxidative stress is one of the major limiting factor in plant productivity. Reactive oxygens species (ROS) generated during metabolic processes damage cellular functions and consequently lead to disease, senescence and cell death. Plants have evolved an efficient defense system by which the ROS is scavenged by antioxidant enzymes such as superoxide dismutase (SOD) and ascorbate peroxidase (APX). Attempts to reduce oxidative damages under the stress conditions have included the manipulation of 갠 scavenging enzymes by gene transfer technology. Increased SOD activities of transgenic plants lead to increased resistance against oxidative stresses derived from methyl viologen (MV), and from photooxidative damage caused by high light and low temperature. Transgenic tobacco plants overexpressing APX showed reduced damage following either MV treatment of photooxidative treatment. Overexpression of glutathion reductase (GR) leads to increase in pool of ascorbate and GSH, known as small antioxidant molecules. These results indicate through overexpression of enzymes involved in ROS-scavenging could maintain or improve the plant productivities under environment stress condition. In this study, the rational approaches to develop stress-tolerant plants by gene manipulation of antioxidant enzymes will be introduced to provide solutions for the global food and environmental problems in the $21^\textrm{st}$ century.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2010.10a
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• pp.17-17
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• 2010

Rhizobacteria are a diverse group of free-living soil bacteria that live in plant rhizosphere and colonized the root system. Plant growth-promoting rhizobacteria (PGPR) possessing ACC deaminase (ACCD) can reduce ACC and ethylene in plant tissue and mediated the growth of plants under various stresses including salt stress. ACCD decrease ethylene levels in plant tissue that produce high levels of ethylene in tissue via elevated levels of ACC under salt stress. We selected strains of Pseudomonas sp. possessing ACCD activity for their ability to promote plant growth under salt stress from soil sample collected at Byeonsan, Jeonbuk, South Korea. The Pseudomonas strains possessing ACCD increased the rate of the seedling and growth of chinese cabbage seeds under salt stress. We cloned ACCD gene from P.fluorescens and expressed recombinant protein in Escherichia coli. The active form of recombinant ACCD converted ACC to a-ketobutyrate. The in vivo treatment of recombinant ACCD itself increase the rate of the seedling and growth of Chinese cabbage seeds under salt stress. The polyclonal P.fluorescens anti-ACCD antibody specifically reacted with ACCD originated from Pseudomonas. This indicates that the antibody might act as an important indicator for ACCD driven from Pseudomonas exhibiting plant growth-promoting activity. This study will be useful for identification of newly isolated PGPR containing ACCD and exploioting the ACCD activity from PGPR against various biotic and abiotic stresses.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2002.11a
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• pp.85.2-86
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• 2002

• Journal of Plant Biotechnology
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• v.38 no.2
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• pp.151-161
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• 2011

Plant proteomics is the large-scale studies of proteins, particularly on their structures and functions, governed by the physiological metabolism of plant cells. With the development of techniques and strategies in proteomics, proteomics approach is moving forward in systems biology handling sophisticated components of major signaling and biochemical pathways in plants responding to their environment. In Korea, pioneers in plant proteomics are trying to catch up with global trends in plant proteomics; these researchers are not only improving existing techniques in protein extraction but also developing new techniques in proteomics context. In the hot field of abiotic and biotic stress proteomics, 29 and 9 out of 74 papers have been published during the review period from 2005 to 2010, respectively. This present review article provides an overview on the output of Korean plant proteomers while paying special attention to both abiotic and biotic stress proteomics.

• The Plant Pathology Journal
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• v.36 no.1
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• pp.1-10
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• 2020

Since salicylic acid (SA) was discovered as an elicitor of tobacco plants inducing the resistance against Tobacco mosaic virus (TMV) in 1979, increasing reports suggest that SA indeed is a key plant hormone regulating plant immunity. In addition, recent studies indicate that SA can regulate many different responses, such as tolerance to abiotic stress, plant growth and development, and soil microbiome. In this review, we focused on the recent findings on SA's effects on resistance to biotic stresses in different plant-pathogen systems, tolerance to different abiotic stresses in different plants, plant growth and development, and soil microbiome. This allows us to discuss about the safe and practical use of SA as a plant defense activator and growth regulator. Crosstalk of SA with different plant hormones, such as abscisic acid, ethylene, jasmonic acid, and auxin in different stress and developmental conditions were also discussed.

• Journal of Plant Biotechnology
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• v.4 no.2
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• pp.53-58
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• 2002

Adverse environmental conditions such as drought, high salt and cold/freezing are major factors that reduces crop productivity worldwide. According to a survey, 50-80% of the maximum potential yield is lost by these "environmental or abiotic stresses", which is approximately ten times higher than the loss by biotic stresses. Thus, improving stress-tolerance of crop plants is an important way to improve agricultural productivity, In order to develop such stress-tolerant crop plants, we set out to identify key stress signaling components that can be used to develop commercially viable crop varieties with enhanced stress tolerance. Our primary focus so far has been on the identification of transcription factors that regulate stress responsive gene expression, especially those involved in ABA-mediated stress response. Be sessile, plants have the unique capability to adapt themselves to the abiotic stresses. This adaptive capability is largely dependent on the plant hormone abscisic acid (ABA), whose level increases under various stress conditions, triggering adaptive response. Central to the response is ABA-regulated gene expression, which ultimately leads to physiological changes at the whole plant level. Thus, once identified, it would be possible to enhance stress tolerance of crop plants by manipulating the expression of the factors that mediate ABA-dependent stress response. Here, we present our work on the isolation and functional characterization of the transcription factors.n factors.

• Journal of Applied Biological Chemistry
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• v.63 no.4
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• pp.347-355
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• 2020

Several sensors have been developed for soil and plants to assess plant stress due to climate change. Therefore, the objective of the study is to nondestructively evaluate temperature stress on plant by monitoring climatic and soil conditions and plant responses using various sensors. Plant responses were monitored by electrical conductivity in plant stem and sap flow rate. Electrical conductivity in plant stem reflects the physiological activity of plants including water and ion transport. Fully grown Brassica oleracea var. italica was exposed to 20/15 ℃ (day/night) with 16 h photoperiods as a control, low temperature 15/10 ℃, and high temperature 35/30 ℃ while climatic, soil, and plant conditions were monitored. Electrical conductivity in plant stem and sap flow rate increased during the day and decreased at night. Under low temperature stress, electrical conductivity in plant stem of Brassica oleracea var. italica was lower than control while under high temperature stress, it was higher than control indicating that water and ion transport was affected. However, chlorophyll a and b increased in leaves subjected to low temperature stress and there was no significant difference between high temperature stressed leaves and control. Free proline contents in the leaves did not increase under low temperature stress, but increased under high temperature stress. Proline synthesis in plant is a defense mechanism under environmental stress. Therefore, Brassica oleracea var. Italica appears to be more susceptible to high temperature stress than low temperature.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2005.10a
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• pp.31-32
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• 2005

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2005.11a
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• pp.167-167
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• 2005