Forestry sector has witnessed some unprecedented events in the recent past both in terms of galloping biotechnological developments and heated environmental debates over risks associated with release of transgenic trees. Improvements in the in vitro propagation techniques has made it possible to develop tissue culture based plant regeneration protocols just for about any tree species. And with the inclusion of every new species within the realms of tissue culture technology, it becomes a candidate for genetic improvement through recombinant DNA technology, the so called genetic engineering. Poplars and their hybrids serve as the model tree species on which most of the genetic transformation work as been carried out. A lot of work has also gone in genetic transformation of fruit trees and trees of horticultural interests. Trees have been successfully transformed for traits ranging from reduction of length of juvenile phase to alteration of tree architecture to altering wood quality by lignin and cellulose modification. More-over trees have been genetically engineered successfully to combat various types of insect pests and pathogens causing diseases. But all these developments have ignited controversies over the possible benefits and risks associated with transgenic plantations by various environmental agencies and activists. Solutions to most of these concerns can be found out with more intensive prioritized research.

Transient uidA expression was used to optimize parameters required for biolistic transformation of suspension cells of Easter lily, Lilium longiflourm. Maximum uidA expression occurred following bombardment with gold particles as compared to tungsten. A 3hr pre-treatment of suspension cells with 0.125M osmoticum resulted in a 1.5X increase in uidA expression. A helium pressure of 1550 psi combined with a particle travelling distance of 6cm resulted in maximum uidA expression as compared to either 1100, 1200, or 1800 psi. Transient transformation resulted in up to 493 uidA expressing cells/Petri plate. For stable transformation suspension cells of Lilium longiflorum, were co-bombarded with plasmid DNA containing cucumber mosaic virus (CMV) replicase under the rice actin (Act1) promoter and either the bar or PAT genes under the cauliflower mosaic virus (CaMV 355) promoter. Ten regenerated plants contained the transgene as analyzed by PCR, and two of the ten plants were confirmed to contain the transgene by Southern hybridization. The two transgenic plants were independent transformants, one containing the bar gene and the other both the CMV replicase and bar genes. Plants were sprayed at the rosette stage and found to be resistant to 1000 mg/L of phosphinothricin (Trade name-Ignite) indicating expression of the bar gene throughout the leaves when bar was under control of the CaMV 35S promoter.

The expression of a chimeric transgene (nos-npt II) has been examined in 9 years old transgenic poplars (Populus koreana x P. nigra) growing in a nursery. The expression of the gene in twenty six independentely transformed plants were examined by 1) enzyme (NPT II) assay, 2) RT-PCR, and 3) resistance to kanamycin. High NPT II activities in young leaves of all the transformed plants were found even without a selection pressure for antibiotics for 9 years. However, the activity varied with the positions of leaves in the stem in that young leaves showed higher activity than did mature tissues. When leaf segments were cultured in the presence of 150 mg/l kanamycin, only those from young leaves produced vigorously growing callus. However, as in the case of NPTII assay, the leaf segments from mature leaves did not form callus well on the media. RT-PCR with nptII specific primers also showed that amplification products were observed only when RNAs from young tissues were used. The total RNA gel showed that while RNA in young leaves are relatively stable and in a large quantity, those in old leaves were mostly degraded. All the above results suggest that the gene is transcriptionally active only in young tissue even though it is attached to a constituitive promoter. Therefore, the expression of foreign gene in poplar plants seemed to be affected by the metabolic state of the cells and thus vary greatly with the developmental stages and the age of tissue.

A modified $\delta$-endotoxin gene of Bacillus thuringiensis ssp. tenebrionis (B.t.t.), encoding a coleoptera-specific toxin, was utilized to transform citrus plants, Citrus reticulata Blanco 'Ponkan' mandarian. By co-culturing the nucelli with Agrobacterium tumefaciens harboring the modified gene in the binary vector pBinAR-Btt, the chimeric toxin gene was transferred into citrus plants. The transgenic plants were selected on modified Murashige and Skoog medium containing kanamycin. Hybridization experiments demonstrated that the transgenic plants contained and expressed the toxin protein gene.

Successful genetic transformation of plants requires non-chimeric selection of transformed tissues and their subsequent regeneration. With rare exceptions, most transformation protocols still rely heavily on antibiotics for selecting transgenic cells that contain an antibiotic-degrading selectable marker gene. Here, the morphogenic capacity of in-vitro explants of chrysanthemnum and tobacco stems and leaves (control and transgenic) changed with the addition of aminoglycoside antibiotics (AAs), In a test of 6 AAs, phytotoxicity occurred at concentrations of 10 to 25 and 50 to 100$\mu\textrm{g}$ $mL^{-1}$ in chrysanthemum and tobacco explants, respectively. Light conditions as well as explant source and size also had significant effects. The use of transverse thin cell layers (tTCLs), in conjunction with high initial AA selection levels, supported the greatest regeneration of transgenic material (adventitious shoots or callus) and the lowest number of escapes. Flow-cytometric analyses revealed no endodu-plication in chrysanthemum, even at high AA levels. However, this phenomenon was observed in tobacco calli(8C or more), even at low AA concentrations (i.e., 5 to 10 $\mu\textrm{g}$ mL$^{-1}$ ).

A successful, efficient system for multiple shoot induction and plant regeneration of soybean (Glycine max) was established. Four soybean genotypes were compared for organogenic responses on various media cultured under light conditions. The adventitious shoots (98%, 2.6 shoots/cotyledon) directly from one-day-old cotyledon after germination induced by the hormone treatment and its efficiency was higher than any other conditions. The optimal medium for the induction of multiple shoots from cotyledon in Pungsannamulkong(shoot formation rate, 98%), Lx 16 (83%) and IIpumgeomjeongkong(63%) was MS medium supplemented with 2 mg/L BAP, but for Alchankong(75%), MS medium supplemented with 1mg/L zeatin and 1mg/L IAA, 3% sucrose, 4% Phytagel. Higher root induction (88%) was observed from the shoots placed on rooting medium (hormone-free MS basal). Plantlets were transferred onto the same medium supplemented with 1% activated charcoal for further development. With this treatment, regenerated plantlets were obtained within 7-8 weeks (shoot induction for 4 weeks, rooting and shoot elongation for 3-4 weeks).

Somatic embryos were induced from immature cotyledons and cultured on a MS medium containing 40mg/L 2,4-D. The maximum induction of embryos was obtained from immature cotyledons in a size of 3-4mm, and the highest frequency was obtained in the induction medium at pH 7.0. For embryo development, embryogenic tissues were transferred to a MSM6AC and MSM6 media. Developing embryos were placed at 27$^{\circ}C$with dim light (20$\mu$$molm^{-2}$$s^{-1}$) provided by cool fluorescent tubes (3-D wavelength light is better than standard light). Somatic embryos were clearly developed from globular stage to cotyledonary stages. The color of embryo may be a useful parameter for estimation of embryo quality. When the embryo becomes mature, embryo will be ready for desiccation in order to induce roots and shoots of embryos.

This study was conducted to examine differences in shoot regeneration among chrysanthemum cultivars. Leaf explants of chrysanthemum cultivars 'Sulhwa', 'Puma', 'Geummokseo' and 'Sulpoong' were used. Explants cultured on the medium for 2 weeks formed calli at the cut surfaces. Shoots regenerated on MS basal medium supplemented with various concentration combinations of NAA and BAP. Explants were cultured under cool-white fluorescent lamps with a light intensity of $40\mu{Mm}^{-2}$.$s^{-1}$ for 16 $hday^{-1}$, at $25^{\circ}c$ and 70-80% relative humidity. 'Geummokseo' and 'Sulpoong' were the most responsive cultivars in shoot regeneration. Most effective medium for 'Sulhwa' and 'Puma' was MS basal medium supplemented with 10.0 $\mu{M}$ NAA and 5.0 $\mu{M}$ BAP and for 'Geummokseo' MS supplemented with 10.0$\mu{M}$ NAA and 20.0$\mu{M}$ BAP. Regeneration of multiple shoots was observed on MS basal medium supplemented with 1.0$\mu{M}$ or 10.0 $\mu{M}$ NAA and 5.0$\mu{M}$ BAP. High frequency regeneration of adventitious shoots from leaf explants and efficient induction of root from these regenerated shoots were obtained.

Callus induction and somatic embryogenesis are fundamental to cotton tissue culture biotechnology. An efficient protocol for callus induction, somatic embryogenesis and their maturation have been developed to regenerate plantlets from cotton (Gossypium hirsutum L.) variety coker 312. Embryogenic callus was initiated from hypo-cotyl region that was used as an explant at seedling stage when it was about 7-8 days old. Callus induction was achieved through culturing hypocotyls (5-7mm) on $MS_{1a} medium supplemented with 2,4-D (0.1 mg/L) and KT (0.5 mg/L) for six weeks. A friable, colorless, bulky and well proliferating callus becomes greenish with the addition of NAA (2.0 mg/L), ZT (0.1 mg/L) and removal of 2,4-D (M $S_{1b}$) cultured for two weeks then again transferred to $MS_{1a}. 2,4-dichlorophenoxyacetic acid (2,4-D) promoted the proliferation of embryogenic callus, but had a negative effect on the differentiation and germination of somatic embryos. ZT (0.1mg/L) and activated charcoal (2g/L), both hormones play an important role in differentiation and germination of somatic embryos in hypocotyls derived embryogenic callus but in case of cotton, such a capability have been observed on MS medium with 1.92 g/L $KNO_3$, but it is considered to attain somewhat more improvement. High embryogenesis frequency was achieved through nutrient deficient stress treatment. The frequency of globular embryogenesis (two-three folds) was achieved when well proliferating callus was (from $MS_{1a}$ media) cultured on MS (1/5 strength) medium for four weeks. Here the development of anthocyanins is the best indicator for somatic embryogenesis. However, when embryoid callus was cultured on MS (full strength) medium, the globular embryos were developed into normal plantlets immediately. In this procedure 27.49% cotyledenary embryos were developed. Of that 70% cotyledenary embryos were developed not only into normal plantlets but rooted simultaneously, when cultured on MS (with 0.05 mgg/L giberrelic acid) medium. So complete plants could be regenerated through somatic embryogenesis from hypocotyl explants within 6 months.s.

A simple procedure for the extraction of the lipolytic enzyme from rice bran has been developed. High activity of lipolytic enzyme was obtained by first defatting the rice bran to remove lipid components with various extraction conditions. Then, after rove cycles of aqueous extraction, rice bran lipolytic enzyme was purified using micro- and ultrafiltration apparatus. Lipolytic enzyme activity was estimated by its hydrolytic action of tributyrin. The result indicated that the standard activity curve of butyric acid showed that the potential rice bran enzyme is a hydrolytic lipase enzyme. In addition, it showed higher lipolytic activity and specific enzyme activity with further purification by micro- and ultrafiltration. The size of rice bran lipase enzyme was identified through 15 ％ SDS-PAGE. The molecular weight of the rice bran lipase enzyme was 41 kDa.