• Journal of the Korean Wood Science and Technology
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• v.18 no.3
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• pp.26-33
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• 1990

To study the wood quality factors of Populus nigra $\times$ maxmowiczii known a rapidly growing species, the variations of green moisture contents, bulk density, wood fibre dimensions, microfibril angles, and number of leaf knot in stem wood were investigated. The heartwood contained a higher moisture content than the corresponding sapwood. Bulk density in radial patterns variations decrease outward from the pith, then increase toward the bark. The wood-fiber length and diameters had somewhat smaller values than on Populus alba $\times$ glandulosa or Populus euramericana. The microfibril angles decreased rapidly toward the outside, and their mean values were about 16 degree. The grain angles run nearly parallel to the cell axies. Number of leaf knot showed a fluctural change above ground level to a point near the base of the crown and then increased rapidly to the top of tree and average number of leaf knot varied exclusively from tree to tree.

• Journal of Korea Foresty Energy
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• v.24 no.1
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• pp.39-46
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• 2005

In this study, the possibility of sugar conversion of poplar wood(Populus $alba{\times}rglandulosa$) and their degradation features of major wood components were characterized using flow type supercritical water treatment system. The finely ground poplar wood meals were treated for 2min. under subcritical condition$(23MPa,\;275^{\circ}C\;and\;325^{\circ}C)$ and supercritical condition $(23MPa,\;375^{\circ}C\;and\;415^{\circ}C)$. respectively. The degradation products of poplar wood meals appeared brownish colors, including undegraded solids. Increasing the temperature of the system, the degradation rate of poplar wood meals was accelerated and reached up to $94\%\;at\;375^{\circ}C$. The total amount of reducing sugars in degradation products determined by DNS method were gradually lowered when the temperature condition became severe. This indicated that the reducing sugars formed were further degraded to kan derivatives by certain side reaction such as pyrolysis under higher temperature. In order to characterize degradation features of lignin, the degradation products were extracted with ethylacetate and the organic phases were subjected to GC-MS analysis. Main lignin degradation products were identified to vanillin, guaiacol, syrinaldehyde, 4-prophenyl syringol and dihydrosinapyl alcohol, which could be formed by the cleavage of ether linkages in lignin polymers by high temperature condition.

• Journal of Korea Foresty Energy
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• v.22 no.2
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• pp.1-17
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• 2003

Populus species have been as a model species in tree breeding and we have enormous varieties resulting from the poplar breeding because of their fast growth performance and short rotation age. New varieties developed in Korea are common italian poplar(P euramericana, I-214, I-476), P euramericana“Eco 28”(Italian poplar No.1) and p. deltoides“Lux”(Italian poplar No.2), which were introduced from foreign countries. As hybrid polars, Hyun-Sasi(p. alba ${\times}$ P. glandulosa No.1, No.2, No.3, No4.), P. nigra x P. maximowiczii and P. koreana x P. nigra val. italica, were developed, and P. davidiana was selected as the result of selection breeding The total plantation areas covered with the new varieties are 935,162ha that include 745,773ha of P. euramericana, 184,636ha of P. alba x P. glandulosa, and other new varieties are 4,735ha. The new poplars are contributed to increase farmer's income as well as bare land tree-planting in Korea. The technologies associated with the poplar species were developed, such as the determination of optimum site for new the poplar species, the crossing method between incompatible poplar species, and the vegetative mass propagation. In the future, poplar species will be considered for phytoremediation species at contaminated areas such as landfill sites or with lives stock's waste water as well as wood production, a shade tree like road-side tree and public park tree.

• 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.

• Korean Journal of Plant Tissue Culture
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• v.26 no.3
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• pp.163-169
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• 1999

This study was conducted to produce herbicide resistant plants by transferring phosphinothricin acetyltransferase (PAT) gene into Populus alba $\times$ Populus glandulosa No .3 using Agrobacterium tumefaciens MP 90/PAT. Leaf segments from in vitro grown shoots of hybrid poplar No. 3 were soaked in a AB medium containing Agrobacterium tumefaciens MP 90/PAT for 10 min and cocultivated for 2 days on MS medium containing 1.0 mg/L 2,4-D and 0.2mg/L kinetin (CIM). Putative transformed calli could be selected after cocultivation of leaf segments on CIM supplemented with 50mg/L kanamycin and 500mg/L cefotaxime for 3 weeks. The selected calli were cultured on CIM supplemented with 50 mg/L kanamycin and 500 mg/L cefotaxime for 5~8 weeks before transfer to WPM containing 1.0mg/L zeatin, 0.1mg/L BAP, 50 mg/L kanamycin and 500mg/L cefotaxime for shoot regeneration. Shoots were regenerated from the callus after 4 week cultivation, and the regenerants were grown on the same medium for 7~l0 weeks. The plants rooted on 1/2 WPM containing 0.2 mg/L IBA and 50 mg/L kanamycin. To confirm the gene insertion into plants, GUS activity was detected by histochemical assay in the transformed plants. Finally, the presence of both NPT II and PAT genes from the transgenic plants were confirmed by PCR amplification with the gene specific primers and subsequent PCR-Southern blot with DIG-labeled PAT gene probe. After acclimatization in pots for 4 weeks, the plants were sprayed by 3 mL/L of Basta to test resistance to the herbicide. The transgenic plants remained green, whereas all the control plants died after one week.

• Journal of Korean Society of Forest Science
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• v.98 no.5
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• pp.513-523
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• 2009

Many species, cultivars, and hybrids in Populus have been introduced and developed by the scientists of Department of Forest Genetic Resources, Korea Forest Research Institute in Korea. P. alba ${\times}$ glandulosa, P. euramericana, P. nigra ${\times}$ maximowiczii, P. koreana ${\times}$ P. nigra var. italica, and P. davidiana have been studied from many aspects, i.e., genetics, breeding, physiology, propagation, silviculture, biomass production, biotechnology and phytoremediation. These precedent results will provide a sound basis for a newly-arising research on short-rotation coppice as one of renewable resources and phytoremediation plants. It was found that there were many promising varieties and clones for these purposes. However, minute analysis on specific gravity and caloric values for those plants should be followed under several silvicultural and rotational systems.

• Journal of Plant Biotechnology
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• v.48 no.1
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• pp.34-43
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• 2021

Targeted genome editing using the CRISPR/Cas9 system is a ground-breaking technology that is being widely used to produce plants with useful traits. However, for woody plants, only a few successful attempts have been reported. These successes have used Agrobacterium-mediated transformation, which has been reported to be very efficient at producing genetically modified trees. Nonetheless, there are unresolved problems with plasmid sequences that remain in the plant genome. In this study, we demonstrated a DNA-free genome editing technique in which purified CRISPR/Cas9 ribonucleoproteins (RNPs) are delivered directly to the protoplasts of a hybrid poplar (Populus alba × Populus glandulosa). We designed three single-guide RNAs (sgRNAs) to target the stress-associated protein 1 gene (PagSAP1) in the hybrid poplar. Deep sequencing results showed that pre-assembled RNPs had a more efficient target mutagenesis insertion and deletion (indel) frequency than did non-assembled RNPs. Moreover, the RNP of sgRNA3 had a significantly higher editing efficacy than those of sgRNA1 and sgRNA2. Our results suggest that the CRISPR/Cas9 ribonucleoprotein-mediated transfection approach is useful for the production of transgene-free genome-edited tree plants.

• Journal of Korean Society of Forest Science
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• v.90 no.4
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• pp.495-504
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• 2001

The objectives of this study were to understand the characteristics of Cd and Pb accumulation in various tissues of poplar species and the effects of ectomycorrhizal inoculation on the accumulation of above two heavy metals in the tissues. The mycelial inoculum of ectomycorrizal fungus, Pisolithus tinctorius was produced in peatmoss and vermiculite mixtures, and inoculated into potted soil with fresh cuttings of four species of Populus, P. alba ${\times}$ glandulosa (Pag). P. koreana ${\times}$ nigra var. italica (Pkn), P. nigra ${\times}$ maximowiczii(Pnm), and P. euramericana(Pe). The potted soils were added with 0, 30, and 80 ppm Cd, and 0, 50, and 300 ppm Pb. The cuttings were grown outdoors for about five months until the plants were harvested for measurement of growth, mycorrhizal infection, and metal contents in leaves, stems, and roots. The total dry weight of Pe treated with Cd and Pb was increased by mycorrhizal inoculation, while that of three other species was not affected by the inoculation. Cd was accumulated in the highest concentration in Pag and its concentration was increased by four times by mycorrhizal inoculation. The Pag accumulated Cd in the highest concentration in the leaves, while three other species accumulated Cd most in the roots. Pb was accumulated in the highest concentration in the roots of all the four species, while Pkn accumulated Pb in the leaves as much as in the roots. Without mycorrhizal inoculation Pe accumulated Pb most among the four species, while Pkn with mycorrhizal inoculation accumulated Pb two times more than in the same species without mycorrhizal inoculation. It was concluded that Pag was the most effective species among the four poplar species in Cd absorption from contaminated soil, and that Pe instead effectively absorbed Pb. Mycorrhizal inoculation increased the Cd accumulation in the tissues by four times in Pag and also increased Pb accumulation by two times in Pkn, with leaves being the major sites of metal accumulation. It may be possible to use these two poplar species in remedying the metal in the soil through the raking and removing the litter out of the contaminate site.

• Korean Journal of Plant Tissue Culture
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• v.22 no.3
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• pp.121-126
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• 1995

Diploid plants were obtained by anther culture of tetraploid poplar(Populus alba L. X P.glandutosa Uyeki). The effect 2,4D on callus formation from anther culture was greater than any other auxins tested. The highest average number of multiple shoots per callus was obtained when zeatin was used at levels of 6-8 ${\mu}$M. Regenerated shoots were excised and transferred to MS basal medium. Rooted plantlets were subsequently transferred to pots containing artificial soil mix. Finally 100 plane were transplanted in nursery located in forest Genetics Research Institute. for the 300 anther clones growing in greenhouse for 6 months after transplanting, 33% were slow-growing, 47% were rapid-growing and 20% had huge leaf size with rapid-growing characteristics. Chromosome study showed a narrow range of variation from diploid to tetraploid. DNA polymorphism studies using various RAPD markers revealed some extend of differences among the anther-clones in their band pattern.

• 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.