• BMB Reports
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• v.33 no.1
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• pp.69-74
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• 2000

The Arabidopsis thaliana S-Adenosylmethionine decarboxylase (AdoMetDC) cDNA ($GenBank^{TM}$ U63633) was cloned, then the AdoMetDC protein was expressed and purified. The purified AdoMetDC was inactivated by salicylaldehyde in a pseudo first- order kinetics. The secondorder rate constant for inactivation was 126 $M^{-1}min^{-1}$ with the slope of n=0.73, suggesting that inactivation is the result of the reaction of one lysine residue in the active site of AdoMetDC. Site-specific mutagenesis was performed on the AdoMetDC to introduce mutations in conserved $lysine^{81}$ residues. These were chosen by examination of the conserved sequence and proved to be involved in enzymatic activity by chemical modification. Changing $Lys^{81}$ to alanine showed an altered optimal pH. The substrate also provided protection against inactivation by salicylaldehyde. Considering these results, we suggest that the $lysine^{81}$ residue may be involved in catalytic activity.

• Journal of Plant Biology
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• v.39 no.4
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• pp.249-256
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• 1996

Beet curly top virus is the DNA virus that is providing useful for basic studies of the infection of Arabidopsis thaliana with viral host and provides a system for studying both resistance and the molecular basis of symptom development. An importnat aspect of symptom development observed in BCTV-infected A. thaliana (ecotype Sei-O) was the induction of cell division on phloem and surrounding cortex cells. Analysis of the expression of GUS reporter gene activity in transgenic plants containing constructs with promoter of the auxin-inducible saur gene showed that saur promoter activity was induced concomitantly in symptomatic tissues at the inflorescence shoot tips of the transgenic lines. The auxin sensitivity tests showed that hypersusceptible ecotype, Sei-O produced more amounts of callus than susceptible ecotype, Col-O. These studies indicated that changes in auxin concentration were involved in the induction of cell division in BCTV-infected plants and clearly demonstrated that there was a strong correlation between auxin-induced gene expression and the activation of cell division.

• Mycobiology
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• v.44 no.3
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• pp.162-170
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• 2016

In this paper, we demonstrate the ability of Arabidopsis thaliana to detect different mixtures of volatile organic compounds (VOCs) emitted by the common indoor fungus, Aspergillus versicolor, and demonstrate the potential usage of the plant as a bioindicator to monitor fungal VOCs in indoor air. We evaluated the volatile production of Aspergillus versicolor strains SRRC 108 (NRRL 3449) and SRRC 2559 (ATCC 32662) grown on nutrient rich fungal medium, and grown under conditions to mimic the substrate encountered in the built environment where fungi would typically grow indoors (moist wallboard and ceiling tiles). Using headspace solid phase microextraction/gas chromatography-mass spectrometry, we analyzed VOC profiles of the two strains. The most abundant compound produced by both strains on all three media was 1-octen-3-ol. Strain SRRC 2559 made several terpenes not detected from strain SRRC 108. Using a split-plate bioassay, we grew Arabidopsis thaliana in a shared atmosphere with VOCs from the two strains of Aspergillus versicolor grown on yeast extract sucrose medium. The VOCs emitted by SRRC 2559 had an adverse impact on seed germination and plant growth. Chemical standards of individual VOCs from the Aspergillus versicolor mixture (2-methyl-1-butanol, 3-methyl-1-butanol, 1-octen-3-ol, limonene, and ${\beta}-farnesene$), and ${\beta}-caryophyllene$ were tested one by one in seed germination and vegetative plant growth assays. The most inhibitory compound to both seed germination and plant growth was 1-octen-3-ol. Our data suggest that Arabidopsis is a useful model for monitoring indoor air quality as it is sensitive to naturally emitted fungal volatile mixtures as well as to chemical standards of individual compounds, and it exhibits relatively quick concentration- and duration-dependent responses.

• BMB Reports
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• v.53 no.3
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• pp.160-165
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• 2020

The root meristem of Arabidopsis thaliana is protected by the root cap, the size of which is tightly regulated by the balance between the formative cell divisions and the dispersal of the outermost cells. We isolated an enhancer-tagged dominant mutant displaying the short and twisted root by the overexpression of ZINC-FINGER OF ARABIDOPSIS THALIANA1 (ZAT1) encoding an EAR motif-containing zinc-finger protein. The growth inhibition by ZAT1 was shared by ZAT4 and ZAT9, the ZAT1 homologues. The ZAT1 promoter was specifically active in the outermost cells of the root cap, in which ZAT1-GFP was localized when expressed by the ZAT1 promoter. The outermost cell-specific expression pattern of ZAT1 was not altered in the sombrero (smb) or smb bearskin1 (brn1) brn2 accumulating additional root-cap layers. In contrast, ZAT4-GFP and ZAT9-GFP fusion proteins were distributed to the inner root-cap cells in addition to the outermost cells where ZAT4 and ZAT9 promoters were active. Overexpression of ZAT1 induced the ectopic expression of PUTATIVE ASPARTIC PROTEASE3 involved in the programmed cell death. The EAR motif was essential for the growth inhibition by ZAT1. These results suggest that the three related ZATs might regulate the maturation of the outermost cells of the root cap.

• Journal of Environmental Science International
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• v.17 no.9
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• pp.1015-1021
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• 2008

This study was performed to examine the accumulated concentrations (conc.) of cadmium (Cd) in the organs of Arabidopsis thaliana grown in the soil with different conc. of Cd. The official standard conc. of Cd of pollutant exhaust notified by the Korean ministry of environment (0.1 mg/L) and ten times higher (1 mg/L) and fifty times higher (5 mg/L) conc. and no Cd in the soil as control were used for this investigation. The results showed that accumulated conc. of Cd in the stems of plant grown in the soil with different conc. (0.1, 1 and 5 mg/L) were increased 9%, 24% and 286% respectively, compared with normal plant stem. The accumulated conc. of Cd in the leafs of plant gown in the soil with official standard conc. and conc. ten times higher and conc. fifty times higher were increased 3%, 22% and 453%, respectively, compared with normal plant leaf. The accumulated conc. of Cd in the root of plant grown in the soil with 0.1 and 1 mg/L conc. of Cd were increased 6%, 19%, respectively, compared with normal plant root. However, it was observed about 84% of increased accumulation of the Cd in the root of plant, when highest (5 mg/L) conc. was used. The accumulated conc. of Cd in the different organs of Arabidopsis thaliana were increased according to increase of Cd conc. in the soil. When official standard conc. and ten times higher conc. of Cd were used, the accumulated conc. of Cd increased average 6%, 21%, respectively, compared with normal plant organ, and the accumulated conc. of Cd between leaf, stem and root were not significant. However, the accumulated conc. of Cd in the plant organs gown in the conc. fifty times higher were increased about 285%, compared with normal plant. In addition, the accumulated conc. of Cd in different organs of Arabidopsis thaliana exhibited wide differences between organs, that is, stem was increased 118% than root, leaf was increased 256%, 64% than root and stem, respectively. These results show that accumulated conc. of Cd in Arabidopsis thaliana with highest (5 mg/L) conc. of Cd in soil, were much higher in the leaf than the stem or root in proportion to the conc. of Cd contaminated within the soil.

• Proceedings of the Botanical Society of Korea Conference
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• 1996.07a
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• pp.19-25
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• 1996

Three key genetic loci required for proper progression of leaf senescence were identified in Arabidopsis thaliana. Mutations in these loci cause delay in all senescence symptoms examined, including both anabolic and catabolic activities, during natural senescence and upon artificial senescence induced by various senescence-inducing treatments. The result provides a decisive evidence that leaf senescence is a genetically programmed phenomenon controlled by several monogenic loci in Arabidopsis thaliana. The result further indicates that leaf senescence caused by various senescence signals occurs, at least in part, through common pathways in Arabidopsis and that the threed genetic loci function at the common steps.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3475-3478
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• 2010

• Bulletin of the Korean Chemical Society
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• v.18 no.6
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• pp.648-653
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• 1997

Acetolactate synthase was purified from Escherichia coli MF2000/pTATX containing Arabidopsis thaliana acetolactate synthase gene. Purification steps included DEAE cellulose ion exchange column chromatography, phenyl sepharose hydrophobic column chromatography, hydroxylapatite affinity column chromatography, and Mono-Q HPLC. Molecular weight was estimated to be ∼65 KDa and purification fold was 109 times. The enzyme showed a pH optimum of 7 and the $K_M$ value was 5.9 mM. The purified enzyme was not inhibited by any of the end products, valine, leucine, and isoleucine.

• The Plant Pathology Journal
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• v.27 no.2
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• pp.170-182
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• 2011

Plants possess multiple resistance mechanisms that protect themselves against pathogen attack. To identify unknown components of the defense machinery in Arabidopsis, gene-expression changes were monitored in Arabidopsis thaliana under 18 different biotic or abiotic conditions using a DNA microarray representing approximately 25% of all Arabidopsis thaliana genes (www.genevestigator.com). Seventeen genes which are early responsive to salicylic acid (SA) treatment as well as pathogen infection were selected and their T-DNA insertion mutants were obtained from SALK institute. To elucidate the role of each gene in defense response, bacterial pathogen Pseudomonas syringae pv. tomato (Pst) DC3000 was inoculated onto individual T-DNA insertion mutants. Four mutants exhibited decreased resistance and five mutants displayed significantly enhanced resistance against Pst DC3000-infection as measured by change in symptom development as compared to wild-type plants. Among them, member of uridin diphosphate (UDP)-glycosyltransferase (UGT) was of particular interest, since a UGT mutant (At1g05680) showed enhanced resistance to Pst-infection in Arabidopsis. In systemic acquired resistance (SAR) assay, this mutant showed enhanced activation of SAR. Also, the enhanced SAR correlated with increased expression of defense-related gene, AtPR1. These results emphasize that the glycosylation of UGT74E2 is a part of the SA-mediated disease-resistance mechanism.

• Journal of Microbiology and Biotechnology
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• v.21 no.7
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• pp.686-696
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• 2011

To deal with pathogens, plants have evolved sophisticated mechanisms including constitutive and induced defense mechanisms. Phytohormones play important roles in plant growth and development, as well as in the systemic response induced by beneficial and pathogen microorganisms. In this work, we identified an Aspergillus ustus isolate that promotes growth and induces developmental changes in Solanum tuberosum and Arabidopsis thaliana. A. ustus inoculation on A. thaliana and S. tuberosum roots induced an increase in shoot and root growth, and lateral root and root hair numbers. Assays performed on Arabidopsis lines to measure reporter gene expression of auxin-induced/ repressed or cell cycle controlled genes (DR5 and CycB1, respectively) showed enhanced GUS activity, when compared with mock-inoculated seedlings. To determine the contribution of phytohormone signaling pathways in the effect elicited by A. ustus, we evaluated the response of a collection of hormone mutants of Arabidopsis defective in auxin, ethylene, cytokinin, or abscisic acid signaling to the inoculation with this fungus. All mutant lines inoculated with A. ustus showed increased biomass production, suggesting that these genes are not required to respond to this fungus. Moreover, we demonstrated that A. ustus synthesizes auxins and gibberellins in liquid cultures. In addition, A. ustus induced systemic resistance against the necrotrophic fungus Botrytis cinerea and the hemibiotrophic bacterium Pseudomonas syringae DC3000, probably through the induction of the expression of salicylic acid, jasmonic acid/ethylene, and camalexin defense-related genes in Arabidopsis.