• Molecules and Cells
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• 제27권6호
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• pp.641-649
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• 2009

Pyrophosphate:fructose-6-phosphate 1-phosphotransferase (PFP) catalyzes the reversible interconversion of fructose-6-phosphate and fructose-1,6-bisphosphate, a key step in the regulation of the metabolic flux toward glycolysis or gluconeogenesis. To examine the role of PFP in plant growth, we have generated transgenic Arabidopsis plants that either overexpress or repress Arabidopsis PFP subunit genes. The overexpressing lines displayed increased PFP activity and slightly faster growth relative to wild type plants, although their photosynthetic activities and the levels of metabolites appeared not to have significantly changed. In contrast, the RNAi lines showed significantly retarded growth in parallel with the reduced PFP activity. Analysis of photosynthetic activity revealed that the growth retardation phenotype of the RNAi lines was accompanied by the reduced rates of $CO_2$ assimilation. Microarray analysis of our transgenic plants further revealed that the altered expression of $AtPFP{\beta}$ affects the expression of several genes involved in diverse physiological processes. Our current data thus suggest that PFP is important in carbohydrate metabolism and other cellular processes.

• BMB Reports
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• 제42권8호
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• pp.486-492
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• 2009

OsDREB1D, a special DREB (dehydration responsive element binding protein) homologous gene, whose transcripts cannot be detected in rice (Oryza sativa L), either with or without stress treatments, was amplified from the rice genome DNA. The yeast one-hybrid assay revealed that OsDREB1D was able to form a complex with the dehydration responsive element/C-repeat motif. It can also bind with a sequence of LTRE (low temperature responsive element). To analyze the function of OsDREB1D, the gene was transformed and over-expressed in Arabidopsis thaliana cv. Columbia. Results indicated that the over-expression of OsDREB1D conferred cold and high-salt tolerance in transgenic plants, and that transgenic plants were also insensitive to ABA (abscisic acid). From these data, we deduced that this OsDREB1D gene functions similarly as other DREB transcription factors. The expression of OsDREB1D in rice may be controlled by a special mechanism for the redundancy of function.

• Journal of Plant Biotechnology
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• 제31권3호
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• pp.231-237
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• 2004

Oxycarotenoids는 녹색식물, 곰팡이, 효모, 버섯 및 세균 등이 만들어 내는 황색, 적색 또는 자색의 polyene계 색소로 분자내에 산소를 함유하며 생체내에서 중요한 역할을 담당하고 있다. 본 실험에서는 Oxycarotenoids의 생합성 경로상에 존재하는 $\beta$-carotene hydroxylase 유전자 (Chyb)가 재조합된 Ti-plasmid (pGCHYB)를 A. tumerfacience GV3101에 의해 Arabidopsis thaliana (cv. Columbia)에 형질전환하였다. 50 mg/L hygromycin 함유한 MS 배지에서 선발된 개체를 이용하여 Chyb 유전자의 도입여부를 PCR로 분석한 결과, 대조구에서는 Chyb 유전자의 증폭 되지 않았으나 형질전환체에서는 증폭 산물을 확인 할 수 있었다. 또한 형질전환체의 발현여부를 RT-PCR분석한 결과 도입된 Chyb 유전자가 안정적으로 발현되었다. 형질전환체의 carotenoids를 HPLC 분석한 결과 xanthophyll cycle carotenoids (violaxanthin과 zeaxanthin)의 함량 및 $\beta$-carotene 함량은 감소되었으며, 대조구 Arabidopsis에는 생합성되지 않는 astaxanthin이 생합성되었다. 따라서 본 실험에서 육성된 형질전환체를 이용하여 oxycarotenoids 생합성 과정상의 중간대사물질의 표지, 관여된 transcript 및 metabolite 분석 등을 통해 carotenoids 대사계의 연구소재로 활용 할 수 있을 것으로 기대한다.

• Journal of Plant Biotechnology
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• 제31권3호
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• pp.191-195
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• 2004

복합스트레스 내성 유전자 NDP kinase 2 유전자를 도입시킨 형질전환 감자를 개발하기 위하여 이 유전자를 산화스트레스에 의해 발현이 강하게 유도되는 SWPA2 프로모터 또는 enhanced CaMV 35S 프로모터에 연결한 벡터를 제작한 후 각각 Agrobacterium 매개로 형질전환 하였다. 기관발생 경로에 의해 kanamycin 저항성 식물체를 재분화 시킨 후 Southern 분석으로 외래 유전자가 안정적으로 감자 게놈내로 삽입되었음을 확인하였다. 형질전환 감자 식물체의 잎 조직을 대상으로 10 $\mu$M methyl viologen에 대한 내성 검정을 조사하여 산화스트레스 내성 형질전환 감자 식물체를 2 개체씩 선발하였다. 선발된 식물체는 건조, 고온 등의 여러 가지 환경스트레스 내성 분석을 실시할 예정이며 이로부터 복합재해에 내성을 지닌 감자 품종을 개발할 수 있을 것으로 기대한다.

• Molecules and Cells
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• 제39권3호
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• pp.250-257
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• 2016

Abiotic stresses such as drought and low temperature critically restrict plant growth, reproduction, and productivity. Higher plants have developed various defense strategies against these unfavorable conditions. CaPUB1 (Capsicum annuum Putative U-box protein 1) is a hot pepper U-box E3 Ub ligase. Transgenic Arabidopsis plants that constitutively expressed CaPUB1 exhibited drought-sensitive phenotypes, suggesting that it functions as a negative regulator of the drought stress response. In this study, CaPUB1 was over-expressed in rice (Oryza sativa L.), and the phenotypic properties of transgenic rice plants were examined in terms of their drought and cold stress tolerance. Ubi:CaPUB1 T3 transgenic rice plants displayed phenotypes hypersensitive to dehydration, suggesting that its role in the negative regulation of drought stress response is conserved in dicot Arabidopsis and monocot rice plants. In contrast, Ubi:CaPUB1 progeny exhibited phenotypes markedly tolerant to prolonged low temperature ($4^{\circ}C$) treatment, compared to those of wild-type plants, as determined by survival rates, electrolyte leakage, and total chlorophyll content. Cold stress-induced marker genes, including DREB1A, DREB1B, DREB1C, and Cytochrome P450, were more up-regulated by cold treatment in Ubi:CaPUB1 plants than in wild-type plants. These results suggest that CaPUB1 serves as both a negative regulator of the drought stress response and a positive regulator of the cold stress response in transgenic rice plants. This raises the possibility that CaPUB1 participates in the cross-talk between drought and low-temperature signaling pathways.

• The Plant Pathology Journal
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• 제36권3호
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• pp.255-266
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• 2020

Plant immune responses can be triggered by chemicals, microbes, pathogens, insects, or abiotic stresses. In particular, induced systemic resistance (ISR) refers to the activation of the immune system due to a plant's interaction with beneficial microorganisms. The phenolic compound, 2,4-diacetylphloroglucinol (DAPG), which is produced by beneficial Pseudomonas spp., acts as an ISR elicitor, yet DAPG's mechanism in ISR remains unclear. In this study, transgenic Arabidopsis thaliana plants overexpressing the DAPG hydrolase gene (phlG) were generated to investigate the functioning of DAPG in ISR. DAPG was applied onto 3-week-old A. thaliana Col-0 and these primed plants showed resistance to the pathogens Botrytis cinerea and Pseudomonas syringae pv. tomato DC3000. However, in the phlG transgenic A. thaliana, the ISR was not triggered against these pathogens. The DAPG-mediated ISR phenotype was impaired in transgenic A. thaliana plants overexpressing phlG, thus showing similar disease severity when compared to untreated control plants. Furthermore, the DAPG-treated A. thaliana Col-0 showed an increase in their gene expression levels of PDF1.2 and WRKY70 but this failed to occur in the phlG transgenic lines. Collectively, these experimental results indicate that jasmonic acid/ethylene signal-based defense system is effectively disabled in phlG transgenic A. thaliana lines.

• BMB Reports
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• 제52권11호
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• pp.653-658
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• 2019

MYB-type transcription factors (TFs) play important roles in plant growth and development, and in the rapid responses to unfavorable environmental conditions. We recently reported the isolation and characterization of a rice (Oryza sativa) MYB TF, OsMYB102, which is involved in the regulation of leaf senescence by downregulating abscisic acid (ABA) biosynthesis and the downstream signaling response. Based on the similarities of their sequences and expression patterns, OsMYB102 appears to be a homolog of the Arabidopsis thaliana AtMYB44 TF. Since AtMYB44 is a key regulator of leaf senescence and abiotic stress responses, it is important to examine whether AtMYB44 homologs in other plants also act similarly. Here, we generated transgenic Arabidopsis plants expressing OsMYB102 (OsMYB102-OX). The OsMYB102-OX plants showed a delayed senescence phenotype during dark incubation and were more susceptible to salt and drought stresses, considerably similar to Arabidopsis plants overexpressing AtMYB44. Real-time quantitative PCR (RT-qPCR) revealed that, in addition to known senescence-associated genes, genes encoding the ABA catabolic enzymes AtCYP707A3 and AtCYP707A4 were also significantly upregulated in OsMYB102-OX, leading to a significant decrease in ABA accumulation. Furthermore, protoplast transient expression and chromatin immunoprecipitation assays revealed that OsMYB102 directly activated AtCYP707A3 expression. Based on our findings, it is probable that the regulatory functions of AtMYB44 homologs in plants are highly conserved and they have vital roles in leaf senescence and the abiotic stress responses.

• Journal of Plant Biology
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• 제36권3호
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• pp.267-273
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• 1993

Promoters of the chlorophyll a/b bidning protein genes, cab1, and cab2, of Arabidopsis thaliana were studied for their functions in differential expression during greening of etiolated shoots. The etiolated shoots were derived from leaves of transgenic tobacco plants with the cab-CAT (chloramphenicol acetyltransferase) translational fusions, and CAT activity was measured to monitor the activities of the cab promoters. Cab1 promoter activity increased rapidly and showed saturation after about 24 hours of greening, but that of cab2 increased with about 2 day-lag period and showed saturation after 6 days. Cab1 promoter activity was more sensitive to levulinic acid (LA) compared with cab2 activity. Cab2 promoter activity was inhibited more sensitively by chloramphynicol (CAP) than by inhibitors of Chl formation. Cab1 promoter activity was, however, inhibited less sensitively by CAP than by LA. The treatment of abscisic acid (ABA) did not block Chl synthesis so significantly as LA treatment did, and cab2 promoter activity was much less sensitive to ABA compared with that of cab1. These results suggest that cab1 expression is strongly related with Chl formation, possibly with $\delta$-aminolevulinic acid accumulation, and cab2 expression is suppressed more by the blockage of translation of Chl a-apoproteins than by the blockage of Chl a accumulation.

• Molecules and Cells
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• 제24권2호
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• pp.301-306
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• 2007

Tocopherols, essential components of the human diet, are synthesized exclusively by photosynthetic organisms. To increase tocopherol content by increasing total flux to the tocopherol biosynthetic pathway, genes encoding Arabidopsis homogentisate phytyltransferase (HPT/V-TE2) and tocopherol cyclase (TC/VTE1) were constitutively overexpressed in lettuce (Lactuca sativa L.). Total tocopherol content of the transgenic plants overexpressing either of the genes was increased by more than 2-fold mainly due to an increase in ${\gamma}$-tocopherol. However, chlorophyll content in the HPT/VTE2 and TC/VTE1 transgenic lines decreased by up to 20% and increased by up to 35%, respectively (P < 0.01). These results demonstrate that manipulation of the tocopherol biosynthetic pathway can increase or decrease chlorophyll content depending on the gene introduced.

• 한국초지조사료학회지
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• 제43권1호
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• pp.42-49
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• 2023

The plant-specific NAC transcription factors control various biological processes, including plant development and stress responses. We have isolated an ANAC032 gene, one of the NAC transcription factor family, which was highly activated by multi-abiotic stresses, including high salt and drought in Arabidopsis. Here, we generated transgenic plants constitutively expressing ANAC032 and its knockout to identify the functional roles of ANAC032 in Arabidopsis under abiotic stress responses. The ANAC032-overexpressing plants showed enhanced tolerance to salinity and drought stresses. The anac032 knockout mutants were observed no significant changes under the high salt and drought conditions. We also monitored the expression of high salt and drought stress-responsive genes in the ANAC032 transgenic plants and anac032 mutant. The ANAC032 overexpression upregulated the expression of stress-responsive genes, RD29A and ERD10, under the stresses. Thus, our data identify that transcription factor ANAC032 plays as an enhancer for salinity and drought tolerance through the upregulation of stress-responsive genes and provides useful genetic traits for generating multi-abiotic stress-tolerant forage crops.