• Journal of the Korean Wood Science and Technology
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• v.32 no.3
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• pp.15-24
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• 2004

The present work was undertaken to investigate the anatomical and chemical characteristics of transgenic poplar down-regulated with antisense OMT gene. Also the distribution of lignin in transgenic poplar trees was investigated at cellular level. No visible abnormal phenotype was observed in the fibers and vessel elements of transgenic poplar. Any marked differences in the staining intensities of Wiesner and Mäule color reaction were not identified in the transgenic poplar. TEM micrographs did not show any staining intensities in the cell walls stained with KMnO₄. Interestingly, the UV spectroscopy of semi-thin sections exhibited a distinct decrease of lignin absorption at 280 nm in the vessel walls, indicating transgenic poplar wood with lower amount of guaiacyl lignin in vessel elements. Chemical composition of antisense OMT poplar was almost identical to that of wild-type poplar. Klason lignin content of transgenic poplar did not show any significant difference from that of the controls. The solid state NMR spectra revealed the transgenic poplar with only slightly more syringyl lignin than the control. The present work showed that antisense OMT gene constructed in the poplar was not enough to reduce the overall content of Klason lignin, and suggested that the expression of transformation was confined to vessel walls.

• Journal of Plant Biotechnology
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• v.38 no.3
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• pp.228-233
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• 2011

Nucleoside diphosphate kinase 2 (NDPK2) is known to regulate the expression of antioxidant genes and auxin-responsive genes in plants. Previously, it was noted that the overexpression of Arabidopsis NDPK2 (AtNDPK2) under the control of an oxidative stress-inducible SWPA2 promoter in transgenic poplar (Populus alba ${\times}$ P. tremular var. glandulosa) plants (referred to as SN plants) enhanced tolerance to oxidative stress and improved growth (Plant Biotechnol J 9: 34-347, 2011). In this study, growth of transgenic poplar was assessed under living modified organism (LMO) field conditions in terms of biomass in the next year. The growth of transgenic poplar plants increased in comparison with non-transgenic plants. The SN3 and SN4 transgenic lines had 1.6 and 1.2 times higher dry weight in stems than non-transgenic plants at 6 months after planting, respectively. Transgenic poplar also exhibited increased transcript levels of auxin-response genes such as IAA1, IAA2, IAA5 and IAA6. These results suggest that enhanced AtNDPK2 expression increases plant biomass in transgenic poplar through the regulation of auxin-response genes.

• Journal of Plant Biotechnology
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• v.38 no.3
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• pp.203-208
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• 2011

We transferred Dhn5 (dehydrin5) gene from barley to poplar to determine the effect of its expression on the transgenic poplars. The results from northern blot analysis showed that the expression level of gene varied among the transgenic lines. During their culture on tissue culture media, the transgenic poplars formed vigorous growing callus in the presence of 5% PEG. When the transgenic poplars were growing in pots and witheld watering, they stayed much healthier than nontransgenic poplars. The transgenic poplars showed higher rates of photosynthetic rates, stomatal conductance and evaporation rates under the drought stress, although there was no significant difference in soil water content within the treatments. The relative electrical conductivity of the transgenic poplars after 20% PEG treatment was lower than that of nontransgenic poplars. The results provide evidence that the expression of hvDhn5 gene conferred drought tolerance in the transgenic poplars.

• Journal of Korean Society of Forest Science
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• v.86 no.4
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• pp.407-414
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• 1997

The resistance of a non-transgenic poplar clone, 'Ogy' and three transgenic poplar lines to the cottonwood leaf beetle, Chrysomela scripta F., was evaluated by in vitro feeding. The lines were transformed with neomycin phosphotransferase II(NPT II) as a selectable marker, proteinase inhibitor II(pin2) as a resistance gene, and CaMV 35S as a promoter. An efficient method of sterilizing the beetle eggs and introducing them into plant tissue cultures was developed. The resistance of the transgenic lines was investigated in terms of effects tin leaf area consumed, insect weight, insect developmental stages, and plantlet root dry weight after feeding. Also, leaf area consumed was examined by leaf age as measured through leaf plastochron index(LPI). The leaf area consumed and insect weight were highly significant between transformants and control, and insect development in vitro was significant among the transgenic lines. Larval infestation was the most severe around LPI 4 to 5 which were young leaves. The system provided a quick, highly controlled method to screen developing transgenic plantlets directly.

• Journal of Korean Society of Forest Science
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• v.84 no.1
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• pp.77-86
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• 1995

To effectively modify tree function with genetic engineering, transgenes must be expressed at the proper level in the appropriate tissues at suitable developmental stages. Toward understanding the spatial and temporal expression of transgenes in woody plants, transgene expression was evaluated in three greenhouse-grown, transgenic lines of Populus alba ${\times}$ P. grandidentata hybrid clone 'Hansen'. All transgenic poplar lines possess constructs containing the bacterial nopaline synthase(nos) promoter linked to a neomycin phosphotransferase II(NPT II) selectable marker gene. In addition, each transgenic poplar line contains one of the following gene constructs : 1) a wound-inducible potato proteinase inhibitor II (pin2) promoter linked to a chloramphenicol acetyltransferase(CAT) reporter gene. 2) a nos promoter linked to a PIN2 structural gene : or 3) a Cauliflower Mosaic Virus 35s promoter linked to a PIN2 structural gene. Polymerase chain reaction(PCR) was used to verify the presence of foreign genes in the poplar genome. Enzyme-linked immunosorbent assays(ELISAs) were used to evaluate organ specific expression of the nos-NPT II construct. NPT II expression was detected in leaves, petioles, stems, and roots of transgenic poplar, thereby indicating that the nos promoter is potentially effective for general constitutive expression of transgenes. NPT expression varied among transgenic poplar lines and among organs for one transgenic line, Tr15. With Tr15, NPT II levels were highest in older leaves and petioles. These results indicate that screening of several transgenic lines may be required to identify lines with optimal transgene expression.

• Journal of Plant Biotechnology
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• v.5 no.1
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• pp.19-23
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• 2003

The Ac (activator) which is one of the well-characterized transposable elements from maize was examined for its transposition possibility to the heterologous plant (P.nigra x maximowiczii) genome via Agrobacterium tumefacience (LBA4404) mediated transformation system. A number of transgenic plants were successfully recovered after 30 weeks by amount reduction from 50 to 15 g/$m\ell$ kanamycin for in vitro selection to minimize phytotoxic effects and to increase callus growth and regeneration efficiency. Among transgenic plants, 62 out of 106 transgenic poplars (58.5%) showed abnormal phenotypes such as severe serrated leaves and light leaf coloration. Indigo staining with X-gluc proved indirectly the restoration of Gus enzyme function and the presence of Ac in poplar genome by PCR. Southern analysis indicated the transposition and existence of Ac element in poplar genomes. In this research, an Agrobacterium-mediated transformation system in poplar species was developed and identified that Ac derived from maize can be excised and trans posed into other poplar genomes.

• Journal of Life Science
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• v.7 no.3
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• pp.172-175
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• 1997

Transgenic hybrid poplar subclones containing herbicide glyphosate resistant gene (aroA) were treated with ozone at the concentration of 100 nL L$^{-1}$ for 6 hr for 5 consecutive days. The foreign gene expression in leaves of all treated plants was reduced both at transcriptional and translational levels confirmed by Northern and Western blot analysis, respectively, as compared to non-treated control plants. These results indicated that the expression of foreign gene in transgenic plants could be affected by the environmental stresses. Thus, the performance of transgenic plants cultivated on field conditions may be lower than they are expected.

• Journal of Plant Biotechnology
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• v.42 no.2
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• pp.93-103
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• 2015

The isolation, cloning, and characterization of an R2R3-MYB transcription factor gene (MtMYB70) from the model legume Medicago truncatula is reported. MtMYB70 consists of a 768-bp coding sequence corresponding to 255 amino acids. Sequence alignment revealed that MtMYB70 cDNA contains conserved R2R3-type MYB domains with highly divergent C terminal regions. MtMYB70 was found to have relatively low sequence homology with known R2R3-MYB genes. Phylogenetic analysis placed the R2R3-MYB domain of MtMYB70 closest to PtMYB1, a known activator of lignin biosynthesis. Overexpression of MtMYB70 under the control of the 35S promoter in transgenic poplar did not cause a significant difference in total lignin content relative to the control, but glucan content was significantly increased in transgenic poplar. Therefore, MtMYB70 might have regulatory role in the biosynthesis of cell wall structural carbohydrates.

• Journal of Plant Biotechnology
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• v.3 no.3
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• pp.135-140
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• 2001

An Agrobacterium tumefaciens LBA4404 (harboring antisense OMT gene)-mediated transformation method has been developed for poplar (P.nigra x maximowiczii) using prolonging co-cultivation time. Explants on LT (longterm) were induced transgenic calli one month earlier than those from ST (short-term) co-cultivation and remained healthier on LT than ST. With this approach, LT method reduced time to produce transgenic calli. Shoots were successfully regenerated from transgenic calli on SIM (Shoot Induction Medium) and rooted well on the basal medium spontaneously. The presence of antisense OMT gene was verified both by PCR and Southern analysis. Each transgenic poplar was phenotypically indishtinguishable when compared with controls for their growth pattern, leaf morphologies and xylem coloration.

• Journal of Plant Biotechnology
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• v.42 no.4
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• pp.356-363
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• 2015

In order to study genetic engineering in trees, the characterization of genes and promoters from trees is necessary. We isolated the promoter region (867 bp) of Pagns-LTP from poplar (P. alba ${\times}$ P. glandulosa) and characterized its activity in transgenic poplar plants using a ${\beta}$-glucuronidase (GUS) reporter gene. High-level expression of the Pagns-LTP transcript was found in poplar roots, while comparatively low-level expression was found in the young leaves. Pagns-LTP mRNA was not detected in other poplar tissues. Additionally, transgenic poplar plants that contained a Pagns-LTP promoter fused to a GUS reporter gene, displayed tissue-specific GUS enzyme activity localized in root tissue. In silico analysis of the Pagns-LTP promoter sequence reveals the presence of several cis-regulatory elements responsive to phytohormones, biotic and abiotic stresses, as well as those regulating tissue-specific expression. These results demonstrate that the Pagns-LTP promoter has tissue-specific expression activity in poplar roots and leaves that may be involved in organ development and plant resistance to various stresses. Therefore, we anticipate that the Pagns-LTP promoter would be a useful tool to genetically optimize woody plants for functional genomics.