• Korean Journal of Plant Resources
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• v.27 no.4
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• pp.392-399
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• 2014

Plant senescence is one of the survival strategies to use limited nutrients efficiently during growth, development and adaptation. In this study, we isolated a gene (PagSEN1) homologous to SENESCENCE 1 from Populus alba ${\times}$ P. glandulosa. The PagSEN1 gene encodes a putative protein consisting of 243 amino acids containing a rhodanese domain. Southern blot analysis suggested that two copies of the PagSEN1 gene are present in the poplar genome. We characterized its transcriptional expression under various conditions mimicking senescence and environmental stresses. The PagSEN1 was expressed most strongly in mature leaves but most weakly in roots. The gene was significantly up-regulated by treatments with mannitol, NaCl, ABA and JA, but not by cold, SA and GA3. These results indicate that PagSEN1 is involved in senescence response induced by environmental stresses.

• Journal of Korean Society of Forest Science
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• v.83 no.1
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• pp.20-24
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• 1994

In woody species with a long life span, the studies on inheritance of any trait may be very time consuming and laborious. Chloroplast DNA(cpDNA) has been a valuable tool in such studies since it has several unique features such as limited genome size and cytoplasmic inheritance. In the present study, cpDNAs from five different species of Populus(P. alba, P. glandulosa, P. alba${\times}$P. glandulosa, P. davidiana, and P. nigra), and Nicotiana tabacum were compared with regard to restriction fragment length polymophism. The results showed that cpDNAs among the species were very conserved, although some polymorphisms were observed when the DNAs were digested with restriction enzyme EcoRI or KphI. The other enzymes (Bgl II, and PstI) tested produced identical restriction fragmentation pattern among the species. However, cpDNAs from all the five Populus species showed different restriction fragmentation pattern from that of tobacco with the four restriction enzymes tested. Southern hybridization with tobacco rbcL gene fragment as a probe also produced identical pattern among Populus species. The results indicate that cpDNAs in the genus are very well conserved during evolution.

• Journal of Korean Society of Forest Science
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• v.102 no.2
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• pp.198-203
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• 2013

Herein we analyzed the nuclear DNA content and the histological characteristics of the triploid of the 'Hyunsasi' (Populus alba ${\times}$ P. glandulosa $F_1$) which were developed for biomass production and molecular breeding research. The flow cytometric analysis showed that the nuclear DNA content of the 3 triploids were 1.6 times greater than those of the diploid. In terms of histological characteristics, the cross-section area of the stem of 'Line-18' was 1.6 times larger than that of the diploid. The area of pith, and cortex and phloem of the stem of 'Line-18' was also 1.6 and 2.0 times larger than that of the diploid, respectively. Moreover, the length and area of guard cell of 'Line-18' was 1.2 times larger than that of the diploid. These results helps to understand the cytological characteristics of the triploid poplar clones, and further investigations in the growth rate and wood properties of the triploids growing in the field will determine whether the triploid poplars are good candidates for molecular breeding programs and for the improvement of industrial biomass productivity.

• Journal of Korean Society of Forest Science
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• v.101 no.2
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• pp.291-296
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• 2012

Triploids are a useful tool for biomass production and molecular breeding of trees with a long life span. Triploids of the poplar 'Hyunsasi' (Populus alba ${\times}$ P. glandulosa) have been developed by crossing between female diploids and a male tetraploid. The tetraploid was developed around the 1970s at Korea Forest Research Institute by colchicine-induced chromosome doubling. Seedlings of the $F_1$ generation were analyzed using flow cytometry to verify their ploidy status. The mean relative fluorescence index of 3 F1 poplars, labeled as Line- 1, Line-17, Line-18, were approximately 1.5 times higher than those of diploid poplars, and the results clearly indicated that they were triploids. The phenotype of the F1 poplars included larger leaves and thicker stem than diploids, and abnormal leaf morphology, especially in the triploid 'Line-18'. Three triploid lines developed roots more slowly and had less roots than diploid. However, 3 poplar cytotypes (2x, Line-1, Line-17) rooted within 10 days on MS medium. In contrast, compared with the 3 cytotypes, the Line-18 showed about 80% and 70% in the rooting rate and the number of roots. The triploid poplars could be directly utilized for biomass production and with their sterility, they could serve as basic material for genetic transformation. In addition, flow cytometric analysis proved to be an effective and reliable method for screening forest trees for their ploidy level.

• Journal of Korean Society of Forest Science
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• v.89 no.1
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• pp.105-115
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• 2000

This study was conducted to test a hypothesis that sensitivity of trees to ozone exposure was related to their growth rates. Two cultivars of Populus alba ${\times}$ P. glandulosa with different genetic growth potential were used for the comparison. Two clones(72-30, 72-16) of cultivar No. 4 with fast growing potential and three clones(71-28, 72-27, 72-19) of cultivar No. 2 with slow growing potential were propagated in early spring by cutting in $2-{\ell}$ plastic pots. They were grown outdoor for 5 months and exposed in late August for 30 days to 70 and 130ppb ozone in a open-top chambers(2.5m in diameter and 2m in height). Ozone concentration in a control chamber was maintained below 30ppb by filtering with activated charcoal. Each treatment was replicated twenty times. In a control chamber, cultivar No. 4 grew 73%, 64%, and 38% faster than cultivar No. 2 in leaf weight, root weight, and total dry weight, respectively. Visible injury was observed only in cultivar No. 4 in 130ppb treatment. Ozone treatment at both 70 and 130ppb decreased height growth, dry weight of leaf, root, and entire plants in all five clones. Particularly root growth was reduced by 39.7% and 13.8% in cultivar No. 4 and No. 2, respectively, in 70ppb treatment. Consequently, shoot/root ratio of cultivar No.4 was increased by 63.4%, while that of cultivar No.2 was increased by 22.1%. Stomatal conductance decreased more in cultivar No.4 than in cultivar No.2. Net photosynthesis of cultivar No.4 at 130ppb ozone decreased by 69.5%, while that of cultivar No.2 decreased by 31.5%. Above mentioned physiological responses of two cultivars to ozone strongly suggested that fast growing cultivar No.4 was more sensitive to ozone than slow growing cultivar No.2. It was concluded that sensitivity of trees to ozone exposure was closely related to their growth rates.

• Journal of Korean Society of Forest Science
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• v.102 no.3
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• pp.331-337
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• 2013

Formate dehydrogenase (FDH), catalyzing the oxidation of the formate ion to carbon dioxide, is known as the stress protein in response to drought, low temperature and pathogen infection. To study the functions of FDH in poplar (Populus alba ${\times}$ P. glandulosa), we isolated a FDH cDNA (PagFDH1) and examined its expressional characteristics. The PagFDH1 is 1,499 base pairs long and encodes a putative 388 amino acid protein with an expected molecular mass of 42.5 kDa. The PagFDH1 protein has N-terminal mitochondria signal peptide and $NAD^+$ binding domain. Southern blot analysis indicated that a single copy of the PagFDH1 is present in the poplar genome. PagFDH1 is expressed highly in the suspension cells (especially in the lag and early exponential phases) and moderately in roots, flowers and leaves. ABA-mediated enhanced expression of PagFDH1 in response to drought and salt stress treatments indicates that the gene product could play an important role in the development of stress resistant trees.

• Journal of Korea Foresty Energy
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• v.19 no.2
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• pp.93-101
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• 2000

Wood of Robinia pseudoacacia and bark of Populus alba$\times$P. glandulosa, Fraxinus rhynchophylla and Ulmus davidiana var. japonica were collected and extracted with acetone-water(7:3, v/v) in glass jar to examine whether its bioactive compounds exist. The concentrated extracts were fractionated with hexane, chloroform, ethylacetate and water, and then freeze-dried for column chromatography and bioactive tests. The isolated compounds were sakuranetin-5-O-$\beta$-D-glucopyranoside from Populus alba $\times$Pl glandulosa, 4--ethyoxy-(+)-leucorobinetinidin frm R. pseudoacacia and fraxetion from F. rhynchophylla and were characterized by $^1H$ and$^{13}C $ NMR and positive FAB-MS. Decay-resistant activity was expressed by weight loss ratio and hyphae growth inhibition in the wood dust agar medium inoculated wood rot fungi. R. pseudoacacia showed best anti-decaying property in both test and its methanol untreated samples, indicating higher activity than methanol treated samples in hyphae grwoth test. In antioxidative test, $\alpha$-tocopherol, one of natural antioxidants, and BHT, one of synthetic antioxidants, were used as references to cmpare with the antioxidant activities of the extacted fractions. Ethylacetate fraction of F. rhynchophylla bark indicated the hightest activity in this test and all fractions of R. pseudiacacia extractives also indicated higher activities compared with the other fractions. In the isolated compounds, aesculetin isolated from F. rhynchophylla bark showed best activity and followed by robonetinidin from R. pseudoacaica.

• Journal of the Korean Wood Science and Technology
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• v.13 no.2
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• pp.14-34
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• 1985

One of the techniques for altering the properties of wood that has received considerable attention in the last twenty years is the formation of a wood-polymer composite (WPC) by irradiation and heat-catalyst polymerization of a monomer incorporated into the wood matrix. Wood-polymer composites are the new products having the superior mechanical and physical properties and the combinated characteristics of wood and plastic. The purpose of this experiment was to obtain the basic data for the improvement of wooden materials by manufacturing WPC and Staypak. The species examined was Hyunsasi-Namoo (Populus alba ${\times}$ P. glandulosa) which had not been utilized yet. Methylmethacrylate (MMA) as monomer, benzoyl peroxide (BPO) as initiator and methyl alcohol as bulking agent were used. The monomer containing BPO was impregnated into wood pieces by the dipping and the vacuum process for 2 hours. After impregnation, the treated samples were polymerized on the hot press with pressure and heat-catalyst methods. The results obtained were summarized as follows 1. The monomer loading into wood by the dipping process was 12.13 percent and 29.99 percent by the vacuum. The polymer loading into wood by the dipping process was 6.79 percent and 15.44 percent by the vacuum. 2. Comparing with Staypak, antishrink efficiency (ASE) of WPC was 12.5 to 13.6 percent on the radial direction and 14.70 to 18.63 percent on the tangential. Antiswelling efficiency (AE) was 14.40 to 17.22 percent on the radial direction and 17.18 to 42.1 8 to 42.14 percent on the tangential. Reduction in water absorptivity (RWA) was 8.19 to 15.5 percent. As a whole, the vacuum process was better than the dipping. 3. The specific gravity of control, Staypak and WPC were 0.44, 0.66 and 0.61 to 0.62, respectively. 4. In the bending strength test, the strength in case that the load direction is on the radial surface was greater than that which the load direction is on the tangential. 5. Increasing rate of stress at proportional limit in compression perpendicular to grain was 72.26 percent in case of WPC by the dipping process, 78.93 percent by the vacuum and 99.09 percent in case of Staypak.

• BMB Reports
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• v.42 no.7
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• pp.439-443
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• 2009

Dehydrins are group II, late embryogenesis abundant proteins that act putatively as chaperones in stressed plants. To elucidate the function of dehydrins in poplar, we isolated the $SK_2$-type dehydrin gene Podhn from Populus alba $\times$ P. tremula var. glandulosa suspension cells and analyzed its expression following treatments of abiotic stress, wounding and plant growth regulator. Sequence homology and phylogenetic analyses indicate Podhn encodes an acidic dehydrin (pI 5.14, 277 amino acids, predicted size 25.6 kDa) containing two lysine-rich "K-segments" and a 7-serine residue "S-segment", both characteristic of $SK_2$-type dehydrins. Southern blots show Podhn genes form a small gene family in poplar. Podhn was expressed in all tissues examined under unstressed conditions, but most strongly in cell suspensions (especially in the stationary phase). Drought, salt, cold and exogenous abscisic acid (ABA) treatments enhanced Podhn expression, while wounding and jasmonic acid caused its reduction. Therefore, Podhn might be involved in ABA or stress response.

• Korean Journal of Plant Resources
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• v.21 no.3
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• pp.204-209
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• 2008

We have cloned an LTP gene (PoLTP1) from poplar (Populus alba ${\times}$ P. tremula var. glandulosa) suspension cells and examined changes in its expression levels in response to various stresses and ABA treatment. The full-length PoLTP1 cDNA clone encodes a polypeptide of 116 amino acids with typical characteristics of LTPs, notably a conserved arrangement of cysteine residues. Southern blot analysis indicate that two or three copies of the PoLTP1 are present in the genome of the investigated hybrid poplar. In addition, northern analysis of samples from soil-grown plants indicate that PoLTP1 is tissue-specifically expressed in the leaves and flowers. The gene is significantly up-regulated by treatment with mannitol, NaCl and ABA, but not by either cold or wounding. These results indicate that PoLTP1 is involved in osmotic stress responses in poplar plants and suspension cells.