• Plant Biotechnology Reports
• /
• v.4 no.4
• /
• pp.243-251
• /
• 2010

Nitric oxide (NO) has been shown to be involved in diverse physiological processes in microbes, animals and plants. In this study, the involvement of NO in the development and possible roles in oxidative stress protection of Chinese cabbage (Brassica rapa subsp. pekinensis cv. Samrack-ulgari) seedlings were investigated. Exogenous application of sodium nitroprusside (SNP) retarded root elongation, while increasing lateral root formation of Chinese cabbage. Plants showed no signs of external stress due to SNP application in true leaves. Cotyledons of 3-week-old Chinese cabbage plants were found to be highly sensitive to SNP application. Treated cotyledons displayed rapid tissue collapse and associated cell death. Although SNP application reduced root growth under normal growth conditions, it also enhanced methyl viologen (MV)-mediated oxidative stress tolerance. Analysis of SNP application to Chinese cabbage leaf disks, revealed SNP-induced tolerance against oxidative stresses by MV and $H_2O_2$, and evidence includes prevention of chlorophyll loss, superoxide anion (${O_2}^-$) accumulation and lipid peroxidation. This report supports a role for nitric oxide in modulating early seedling development, programmed cell death and stress tolerance in Chinese cabbage.

• Rapid Communication in Photoscience
• /
• v.2 no.3
• /
• pp.79-81
• /
• 2013

A novel method of fabricating polythiophene-gold nanoparticle composite film electrodes for photoelectric conversion is demonstrated. The method includes electrodeposition of gold and electropolymerization of 2,2'-bithiophene onto an indium-tin-oxide (ITO) electrode. First, electrodeposition of gold onto the ITO electrode was carried out with various repetition times of pulsed applied potential (0.25 s at -2.0 V vs. Ag/AgCl) in an aqueous solution of $HAuCl_4$. Significant progress of the number density of deposited gold nanoparticles was confirmed from scanning electron micrographs, from 4 (1 time) to 25% (15 times). Next, electropolymerization of 2,2'-bithiophene onto the above ITO electrode was performed under controlled charge condition (+1.4 V vs. Ag wire, 15 $mC/cm^2$). Structural characterization of as-fabricated films were carried out by spectroscopic and electron micrographic methods. Photocurrent responses from the sample film electrodes were investigated in the presence of electron acceptors (methyl viologen and oxygen). Photocurrent intensities increased with increasing the density of deposited gold nanoparticles up to ~10%, and tended to decrease above it. It suggests that the surplus gold nanoparticles exhibit quenching effects rather than enhancement effects based on localized electric fields induced by surface plasmon resonance of the deposited gold nanoparticles.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.11 no.1
• /
• pp.32-37
• /
• 2006

In this study, we have purified and characterized the membrane bound nitrate reductase obtained from the denitrifying bacteria, Ochrobactrum anthropi SY509, which was isolated from soil samples. O. anthropi SY509 can grow in minimal medium using nitrate as a nitrogen source. We achieved an overall purification rate of 15-fold from the protein extracted from the membrane fraction, with a recovery of approximately 12% of activity. The enzyme exhibited its highest level of activity at pH 5.5, and the activity was increased up to $70^{\circ}C$. Periplasmic and cytochromic proteins, including nitrite and nitrous oxide reductase, were excluded during centrifugation and were verified using enzyme essay. Reduced methyl viologen was determined to be the most efficient electron donor among a variety of anionic and cationic dyestuffs, which could be also used as an electron donor with dimethyl dithionite. The effects of purification and storage conditions on the stability of enzyme were also investigated. The activity of the membranebound nitrate reductase was stably maintained for over 2 weeks in solution. To maintain the stability of enzyme, the cell was disrupted using sonication at low temperatures, and enzyme was extracted by hot water without any surfactant. The purified enzyme was stored in solution with no salt to prevent any significant losses in activity levels.

• Proceedings of the Botanical Society of Korea Conference
• /
• 1999.07a
• /
• pp.79-84
• /
• 1999

Oxidative stress is one of the major environmental stresses to plants. Reactive oxygen species (ROS) generated during metabolic processes damage cellular functions and consequently lead to cell death. Fortunately plants have in vivo defense system by which the ROS is scavenged by enzymes such as superoxide dismutase (SOD) and ascorbate peroxidase (APX). In attempts to understand the protection mechanism of plant against oxidative stress, we developed transgenic tobacco (Nicotiana tabacum cv. Xanthi) plansts thet expressed both SOD and APX in chloroplast using Agrobacterum-mediated transformation and evaluated their protection capabilities against methyl viologen (MV, paraquat) -mediated oxidative damage. Three double transformants (CAI, CA2, and CA3) expressed the chimeric CuZnSOD and chimeric APX in chloroplast, and one transformant (AM) expressed the chimeric APX and chimeric MnSOD in chloroplast. In addition, we obtained three lines of transformants (C/Al, C/A2, and A/C) that expressed the APX and SOD than control plants, and more resistant to oxidative stress caused by MV. TRansformants (C/A and A/C) overexpressing MnSOD, CuZnSOD and APX at the same time showed the highest resistance to MV-mediated oxidative stress among the transformants.

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

• Journal of Plant Biotechnology
• /
• v.38 no.3
• /
• pp.215-220
• /
• 2011

This study was conducted to investigate how to enhance resistance to oxidative stress in petunia progeny obtained by a crossing between transgenic plants, MnSOD (SOD2) ($T_4$) and NDPK2 ($T_2$), to develop transgenic petunia much more resistant to environmental stress. At the treatment of MV 200 ${\mu}M$, the progeny was significantly less damaged than its parental plants (SOD2- or NDPK2-transgenic lines) as well as wild type plants, implying its resistance to oxidative stress was enhanced compare to that of SOD2- or NDPK2- transgenic plants. In an expression of 11 quantitative traits, the progeny remained similar to control plants, although it infrequently displayed slightly longer or wider than either parental or wild type plants. In the expression of 6 qualitative traits, there was no significant difference between parental or non-transgenic control plants.

• Bulletin of the Korean Chemical Society
• /
• v.6 no.3
• /
• pp.145-148
• /
• 1985

The effect of anionic polyelectrolytes, poly(styrenesulfonate) (PSS) and poly(vinylsulfonate) (PVS), on the charge transfer complexing between indole derivatives and methyl viologen($MV^{++}$) cation was investigated. The results were compared with effect of NaCl and an anionic surfactant, sodium dodecylsulfate (SDS). Both PSS and PVS enhanced the complex formation of neutral species (indole and indole acetate at low pH), zwitter ionic tryptophan, and positively charged tryptamine and tryptophan at low pH with $MV^{++}$. This result was attributed to the contribution of hydrophobic interaction, in addition to electrostatic interaction. The enhancing effect of PSS was much higher than that of PVS reflecting the higher hydrophobicity of PSS. The interaction between indole acetate anion and $MV^{++}$ was greatly reduced by addition of PVS and PSS. The higher charge density of PVS was appeared as greater reducing effect indicating the importance of electrostatic force in this case. In all cases, the effect of polyelectrolytes showed maxima, and further addition of PVS and PSS decreased the effect. This behavior was explained in terms of distribution of indole derivatives and $MV^{++}$ in domain of polyanions. The complex formation constants and molar absorptivities of complexes were determined, and the values were compared with those in water and SDS solutions.

• Bulletin of the Korean Chemical Society
• /
• v.7 no.2
• /
• pp.120-124
• /
• 1986

In order to investigate effective solar energy conversion system, the light-induced electron transfer reactions have been examined across single-lamellar liposomes incorporated organic photosensitizers such as anthracene and naphthalene derivatives. We have observed photosensitized reduction of methyl viologen (1,1'-dimethyl-4,4'-$bipyridinium^{2+}$) dissolved in the exterior aqueous phase of the pigmented phospholipid liposomes when EDTA, as electron donor, is dissolved in the enclosed aqueous phase of the liposomes. The anthroyl stearic acid incorporated in the hydrophobic bilayer of liposomes leads to much less quantum yield for the photosensitized reduction of $MV^{2+}$ than the anthracene carboxylate incorporated in the outer hydrophilic layer. However, ${\beta}$-carotene with anthroyl stearic acid incorporated into the bilayer enhances the quantum yield significantly (${\Phi}{\simeq}0.2-0.3$), preventing the reverse reaction of electron transfer ($MV^+_\ {\rightarrow}MV^{2+}$) so that it might be useful for solar energy conversion into chemical energy. A naphthalene derivative, octadecyl naphthylamine sulfonic acid incorporated into the outer layer of liposomes results in less efficiency of $MV^{2+}$ reduction than anthroyl stearic acid. These results have been also tested with respect to lipid components of liposomes.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.40 no.4
• /
• pp.285-290
• /
• 2020

To understand the role of small heat shock protein (sHSPs) in rice plant response to various stresses such as the heat and oxidative stresses, a cDNA encoding a 24.1 kDa mitochondrial small HSP (Oshsp24.1) was isolated from rice by rapid amplification of cDNA ends (RACE) PCR. The deduced amino acid sequence shows very high similarity with other plant small HSPs. DNA gel blot analysis suggests that the rice genome contains more than one copy of Oshsp24.1. High level of expression of Oshsp24.1 transcript was observed in rice seedlings in response to heat, methyl viologen, hydrogen peroxide, ozone, salt and heavy metal stresses. Recombinant OsHSP24.1 protein was produced in E. coli cells for biochemical assay. The protein formed oligomeric complex when incubated with Sulfo-EGS (ethylene glycol bis (succinimidyl succinate)). Our results shows that Oshsp24.1 has an important role in abiotic stress response and have potential for developing stress-tolerant plants.

• Journal of Plant Biotechnology
• /
• v.30 no.4
• /
• pp.405-410
• /
• 2003

Environmental stress is the major limiting factor in plant productivity. In order to evaluate the stress tolerance of potato plants, leaf discs of two potato cultivars, Atlantic and Superior, were subjected to various stress conditions of high temperature, methyl viologen, H2O2, or $H_2O$$_2$. When potato leaf discs were exposed to high temperature at 37$^{\circ}C$ for 84 hr, Atlantic plants, a cultivar with high sensitivity to heat stress, showed about 20％ higher membrane damage than Superior plants. When exposed to 2$\mu$M methyl violgen (MV), a superoxide generating non-selective herbicide, for 36 hr, Atlantic plants also showed about 38％ higher membrane damage than Superior plants, and were more susceptible up to 10$\mu$M MV concentration tested. On treatment with 0.75M NaCl, Atlantic plants also had about 45％ less chlorophyll contents in leaf discs than Superior plants. There was, however, no difference in chlorophyll content of two cultivars at higher NaCl concentrations. The effect of $H_2O$$_2$ on the two cultivars was mixed. At low $H_2O$$_2$ concentration (25 mM) , Superior plants were more susceptible to $H_2O$$_2$stress after 36 hr. However, at high $H_2O$$_2$ concentration (100 mM), Atlantic plants exhibited higher susceptibility after 36 hr. The results indicate that in vitro leaf discs reflecting the whole plants in this study will be useful for selection and characterization of elite transgenic potato plants with enhanced tolerance to environmental stress.