Torenia hybridacv. Summerwave Blue and Violet mainly produce delphinidin. Down regulation of their flavonoid 3'-hydroxylase and flavonoid 3',5'-hydroxylase (F3'5'H) genes and over expression of rose or pelargonium dihydroflavonol 4-reductase (DFR) cDNA yielded pelargonidin-based bright pink flowers. Nierembergia cv. Fairybells lack pink color as they produced only delphinidin and flavonols. Pelargonidin-based pink flowers were achieved by down regulation of F3'5'H and flavonol synthase genes and over expressing rose DFR cDNA. Introduction of petunia F3'5'H and DFR cDNAs into white carnations deficient in DFR activity produced violet carnations, which arc now commercialized in the USA, Canada, Australia, Europe and Japan. Introduction of pansy F3'5'H and iris DFR cDNAs and down regulation of rose DFR gene produced rose flowers which accumulates delphinidin imparting novel violet color.

To study the biochemical and physiological role of the plastidic glucose transporter (pGlcT) in carbohydrate metabolism, we characterized transgenic plants with mutations in the pGlcT gene (GT), gt-1 and gt-2, as well double mutants of GT and the maltose transporter (MEX1) and GT and the triose phosphate/phosphate translocator (TPT), GT and the cytosolic fructose-1,6-bisphosphatase gene (cFBP), and MEX1 and TPT, gt-1/mex2, gt-1/tpt-2, gt-1/cfbp-1, mex1-1/tpt-2, respectively. Compared to the wild type, all mutants except the gt-1/cfbp-1 mutant lines displayed higher starch accumulation and higher levels of maltose. Starch accumulation is due to a decrease in starch turnover, leading to an imbalance between the rates of synthesis and degradation. Sucrose levels of gt alleles were higher than those in wild-type plants during the light period, suggesting possible nightly supplementation via the maltose transport pathway to maintain proper carbohydrate partitioning in the plant leaves. The gt plants displayed less growth retardation than mex1-1 mutant and gt-1/mex2 double mutant displayed accumulativesevere growth retardation as compared to individual gt-1 and mex1-1 mutants, implying that the maltose transporter-mediated pathway is a major route for carbohydrate partitioning at night. The gt-1/tpt-2, mex1-1/tpt-2 and gt-1/cfbp-1 double mutants had retarded growth and low chlorophyll content to differing degrees, indicating that photosynthetic capacity had diminished. Interestingly, the gt-1/tpt-2 line displayed a glucose-insensitive phenotype and higher germination rates than wild type, suggesting its involvement not only in carbon partitioning, but also in the sugar signaling network of the pGlcT and TPT.

Nicotine is most familiar to us as a principal pharmacologically active component of cigarettes. This alkaloid is synthesized in the root in response to insect damage and then transported to the aerial parts of tobacco plants. Here I overview enzymes and genes involved in nicotine biosynthesis, and regulatory mechanisms of gene expression involving the NIC regulatory loci and jasmonic acid.

a-Ketol linolenic acid [KODA, 9,10-ketol-octadecadienoic acid, or 9-hydroxy-10 -oxo-12(Z), 15(Z)-octadecadienoic acid] was found as a stress-induced factor in Lemna paucicostata. KODA reacts with catecholamines to generate many products that strongly induce flowering in L. paucicostata, although KODA itself was inactive. KODA contains an asymmetric carbon at the 9-position in the molecule; the 9-hydroxyl group is predominantly 9R, with an enantiomeric excess of 40% (70% 9R and 30% 9S). We analyzed two major products of the reaction between KODA and norepinephrine, named FN1 and FN2. FN1 was identified as a tricyclic a-ketol fatty acid, 9(R)-11-{(2'R,8’R,10'S,11'S)-2',8'-dihydroxy-7'-oxo-11'-[(Z)-2-pentenyl]-9'-oxa-4'-azatricyclo[6.3.1.01.5]dodec-5'en-10'-yl}-9-hydroxy-10-oxoundecanoic acid. FN2 was the C-9 epimer of FN1. FN1 was derived from 9R-type KODA and FN2 from 9S-type. FN1 showed strong flower-inducing activity, but FN2 was inactive. Pharbitis nil (violet) is a typical short-day plant; flowering can be induced by exposing a seedling cultivated under continuous light to a single 16-h dark period. We analyzed endogenous KODA levels and showed that they were closely related to flower induction: KODA sharply increased in the later part of a 16-h dark period, on the other hand, it failed to increase in the night-break experiment. In addition to it, KODA increased transiently in immature flower buds in all the plants we examined, including P. nil. No such increase of KODA was seen in foliar buds of P. nil. When KODA was sprayed on seedlings of Pharbitis, flower induction was promoted only by the (R)-form of KODA. We also found that KODA enhances flowering in garden plants such as carnations and impatienses. These phenomena indicate that KODA may be involved in flowering formationg of plants and it is potentially useful for a regulating agent for commercial plant flowering.

Much biochemical information on peroxiredoxins (Prxs) has been reported but a genuine physiological function for these proteins has not been established. We show here that two cytosolic yeast Prxs, cPrxI and II, exist in a variety of forms that differ in their structure and molecular weight (MW) and that they can act both as a peroxidase and as a molecular chaperone. The peroxidase function predominates in the lower MW proteins, whereas the chaperone function is more significant in the higher MW complexes. Oxidative stress and heat shock exposure of yeasts causesthe protein structures of cPrxI and II to shift from low MW species to high MW complexes. This triggers a peroxidase-to-chaperone functional switch. These in vivo changes are primarily guided by the active peroxidase site residue, $Cys^{47}$, which serves as an efficient $'H_2O_2-sensor'$ in the cells. The chaperone function of the proteins enhances yeast resistance to heat shock.

A growing body of evidence shows that nitric oxide $({\cdot}NO)$ and ${\cdot}NO-derived$ reactive nitrogen species (RNS) act as both plant physiological regulators and stressors. However, very little is known concerning metabolism of RNS in plant cells. In this paper, we explore a plant metabolic basis for RNS, with special emphasis on the possible relationship to nitrogen assimilation, and discuss the potential of the metabolic engineering for plant-biotechnological application.

Effects of low temperature ($8^{\circ}C$) on the hydraulic conductivity of young roots of a chilling-sensitive (cucumber; Cucumis sativus L.) and a chilling-resistant (figleaf gourd; Cucurbita ficifolia Bouche) crop have been measured at the levels of whole root systems (root hydraulic conductivity, $Lp_r$) and of individual cortical cells (cell hydraulic conductivity, Lp). In figleaf gourd, there was a reduction only in hydrostatic $Lp_r$ but not in osmotic $Lp_r$ suggesting that the activity of water channels was not much affected by low root temperature (LRT)treatment in this species. Changes in cell Lp in response to chilling and recovery were similar asroot level, although they were more intense at the root level. Roots of figleaf gourd recovered better from LRT treatment than those of cucumber. In figleaf gourd, recovery (both at the root and cell level) often resulted in Lp and $Lp_r$ values which were even bigger than the original, i.e. there was an overshoot in hydraulic conductivity. These effects were larger forosmotic (representing the cell-to-cell passage of water) than for hydrostatic $Lp_r$. After a short term (1 d) exposure to $8\;^{\circ}C$ followed by 1 d at $20\;^{\circ}C$, hydrostatic $Lp_r$ of cucumber nearly recovered and that of figleaf gourd still remained higher due to the overshoot. On the contrary, osmotic $Lp_r$ and cell Lp in both species remained high by a factor of 3 as compared to the control, possibly due to an increased activity of water channels. After pre-conditioning of roots at LRT, increased hydraulic conductivitywas completely inhibited by $HgCl_2$ at both the root and cell levels. Different from figleaf gourd, recovery from chilling was not complete in cucumber after longer exposure to LRT. It is concluded that at LRT, both changes in the activity of aquaporins and alterations of root anatomy determine the water uptake in both species. To better understand the aquaporin function in plants under various stress conditions, we examined the transgenic Arabidopsisand tobacco plants that constitutively overexpress ArabidopsisPIP1;4 or PIP2;5 under various abiotic stress conditions. No significant differences in growth rates were found between the transgenic and wild-type plants under favorable growth conditions. By contrast, overexpression of PIP1;4 or PIP2;5 had a negative effect on seed germination and seedling growth under drought stress, whereas it had a positive effect under cold stress and no effect under salt stress. Measurement of water transport by cell pressure probe revealed that these observed phenotypes under different stress conditions were closely correlated with the ability of water transport by each aquaporin in the transgenic plants. Together, our results demonstrate that PIP-type aquaporins play roles in seed germination, seedling growth, and stress response of Arabidopsis and tobacco plants under various stress conditions, and emphasize the importance of a single aquaporin-mediated water transport in these cellular processes.

The Plant Signaling Network Research Center (SigNet) is a government-funded (by Korea's Ministry of Science and Technology (MOST)/ Korea Science and Engineering Foundation (KOSEF)) research center established at the School of Life Sciences and Biotechnology of Korea University in 2003. The SigNet conducts plant biological studies, especially in the field of developmental and defense biology. The research purpose of SigNet is dissection and analysis of plant development and defense signaling network through multiscientific approaches. Knowledge acquired from SigNet research scientists will provide new integrated view of understanding and potential application of plant development and defense mechanism. The other important mission of the SigNet is nurturing Center of Excellence for future outstanding research scientists of Korea. The SigNet will continue to expend every effort to achieve the goals for the future. Through passionate research endeavor of each laboratory and partnerships within inside and outside laboratories, we will continue to develop world-leading plant research group and to educate new generations of innovative researchers. As the SigNet looks toward the future, the SigNet will try to achieve its mission of research, education and service to the community. And the defense response research of our lab will be presented at later part.

The citrus industry represents a major sector of agribusiness in Jeju successfully nurtured by the local governmental farm bureaus for the past three decades. However, in the face of increasing imports effected under the international free trade agreement, the continuous economic viability of the island’s citrus industry is no longer assured. Thus, it entails exploration and development of new agribusiness potentials that are supplemental and/or alternative to the citrus industry. In this presentation, I will discuss two projects of such potentials. (i) Under the tripartite collaboration among Kumho Life and Environmental Science Laboratory, Cheju National University and South Jeju County, genetically engineered turfgrass cultivars possessing both herbicide- and shade-tolerances (gene pyramiding) are currently at final phase of phenotype evaluations and environmental safety assessments. (ii) Fig fruits with longer shelf-life are being developed with support from Jeju HiTech Industrial Development Institute (HiDI) and at its initial phase of development.

Plant tissue culture studies have been done for the preservation of medicinal plant resources and efficient production of pharmaceutically important secondary metabolites. Micropropagation methods for Cephaelis ipecacuanha have been established and these methods enabled much more efficient propagation of the plants than the conventional methods using seedling or layering. The C. ipecacuanha plants derived from tissue culture grew uniformly in the field and they showed higher alkaloid contents compared to the plants grown from seedlings. Hairy root cultures of C. ipecacuanha and Panax ginseng have been established by infection with Agrobacterium rhizogenes, and the production of important pharmaceuticals by these cultures have been successfully demonstrated. In the case of C. ipecacuanha, the highest alkaloid yields from the hairy roots cultured for 8 weeks were 2.75-fold cephaeline (5.5 mg) and one third emetine (0.7 mg) compared with those from the roots of one-year old plant propagated through shoot-tip culture and cultivated in a greenhouse (2.0 mg cephaeline and 2.0 mg emetine). In the case of P. ginseng, ginsenoside contents in the hairy roots optimally cultured for 4 weeks were much higher than those in the roots of 4-year old field-grown plant. Thus our medicinal plant tissue cultures demonstrate desirable properties. However, they are always exposed to danger of microbial contamination or unexpected trouble of culture facilities. Cryopreservation of plant tissue cultures is a reliable method for long-term preservation. Cryopreservation studies on these cultures are also presented.

Transposon-mediated insertional mutagenesis provides one of the most powerful tools for functional studies of genes in higher plants. This project has been performed to develop a large population of insertional mutations, and to construct databases of molecular information on Ds insertion sites in rice. Ultimate goals are to supply genetic materials and information to analyze gene function and to identify and utilize agronomically important genes for breeding purpose. Two strategies have been employed to generate the large scale of transposon population in a Japonica type rice, Dongjin Byeo; 1) genetic crosses between Ac and Ds lines and 2) plant regeneration from seeds carrying Ac and Ds. Our study showed that over 70% of regenerated plants generally carried independent Ds elements and high activity of transposition was detected only during regeneration period. Ds-flanking DNA amplified from leaf tissues of F2 and T1 (or T2) plants have been amplified via TAIL-PCR and directly sequenced. So far, over 65,000 Ds lines have been generated and over 9,500 Ds loci have been mapped on chromosomes by sequence analysis. Database of molecular information on Ds insertion sites has been constructed, and has been opened to the public and will be updated soon at http://www.niab.go.kr. Detailed functional analysis of more than 30 rice mutants has been performed. Several Ds-tagged rice genes that have been selected for functional analysis will be briefly introduced. We expect that a great deal of information and genetic resources of Ds lines would be obtained during the course of this project, which will be shared with domestic and international rice researchers. In addition to the Japonica rice, we have established the tagging system in an rice line of indica genetic background, MGRI079. MGRI079 (Indica/Japonica) was transformed with Agrobacteria carrying Ac and Ds T-DNA vectors. Among transgenic lines, we successfully identified single-copy Ds and Ac lines in MGR1079. These lines were served as ‘starter lines’ to mutagenize Indica genetic background. To achieve rapid, large scale generation of Ds transposant lines, MGR1079 transformants carrying homozygous Ac were crossed with ones with homozygous Ds, and $F_2$seeds were used for plant regeneration. In this year, over 2,000 regeneration plants were grown in the field. We are able to evaluate the tagging efficiency in the Indica genetic background in the fall.

For breeding of a new rootstock for eggplant production, somatic hybrids between two species, Solanum integrifolium and S. sanitwongsei were obtained through protoplast fusion. The former species has been commonly used for rootstock for eggplant production in Japan. Eggplants on these rootstocks are more productive than ungrafted plants, but are susceptible to bacterial wilt caused Ralstonia solanacearum. While the latter species is resistant, the growth of eggplants on this rootstock is rather slow and low yield. Protoplast of both species were isolated from cotyledons, and inactivated with iodoacetamide or UV-irradiation, then fused electrically. The fused products were then cultured. Regenerated plantlets were then transplanted on soil then maintained in a green house. The plants were classified into four groups. Those in the first group showed morphological characters intermediate of the parentalspecies. The plants bore fruit with viable seeds. The plants showed a chromosome number of 2n=48, the sum of those of the parental species, and are suggested to be symmetric fusion products. While plants in the other groupswas less vigorous and showed chromosome number 2n= 68 to 72 suggesting asymmetric fusion products by genomic in situ hybridization(GISH). Isozyme pattern of shikimate dehydrogenase (SKDH; EC 1.1.1.25), isocitrate dehydrogenase (IDH; EC 1.1.1.41) and phosphoglucomutase (PGM; EC 2.7.5.1) showed that 24 regenerated plants in three groups were somatic hybrids. Analysis of random amplified polymorphic DNA (RAPD) showed that 43 S. integrifolium-specific and 57 S. sanitwongsei-specific bands were all found in 24 plants. Both somatic hybrids and its S1 plants were found to be resistant to bacterial wilt, and eggplant grafted these plants using for rootstocks were more productive than grafted mother plants. Now, S1 progenies are used for commercial eggplant production in Osaka Prefecture.

Efficient plant regenerationsystem from cell suspension cultures was established in D. acicularis (2n = 90) by monitoring ploidy level and visual selection of the cultures. The highly regenerable cell lines selected maintained original ploidy level and consisted of compact cell clumps with yellowish color and relatively moderate growth, suggesting that it is possible to select visually the highly regenerable cell lines with the original ploidy level. All the regenerated plantlets from the highly regenerable cell cultures exhibited normal phenotypes and no variations in ploidy level were observed by flow cytometry (FCM) analysis.

Continuous degradation of forest in both quality and quantity threatens wood security in the future. Thus in the future, most wood and pulp will be expected to be produced from plantation forests. We attempt to produce superior trees suitable for such plantations with maximum productivity in limited land area. Tree productivity could be enhanced either by promoting growth and wood quality or by reducing loss caused by abiotic and biotic stresses. Genetic transformation techniques may offer ways to improve the productivity by enabling trees to tolerate the stresses or to covert limited resources into big biomass. With the availability of information on various functional genes and gene transfer techniques, it should be possible to develop such trees. In this presentation, our work to produce such trees at Korea Forest Research Institute is briefly introduced.

Richadella dulcifica, a native shrub in tropical West Africa, gives red berries that have the unusual property of modifying a sour taste into a sweet taste. The red berries contain a taste-modifying protein named miraculin. A synthetic gene encoding miraculin was placed under the control of constitutive promoters and transferred to lettuce. High expression of miraculin was obtained, with accumulation of up to 1% total soluble protein in lettuce leaf. In addition, the miraculin expressed in lettuce possesses a taste-modifying activity.

In the storage roots of sweetpotato (Ipomoea batatas (L.) Lam. cv. Kokei 14), 10 to 20% of starch is essentially unbranched linear amylose and the other major component is branched amylopectin. Amylose is produced by the enzyme GBSSI (granule bound starch synthase I), whereas amylopectin is produced by a concerted action of soluble starch synthase and starch branching enzymes (SBEI and SBEII). We constructed double-stranded RNA (dsRNA) interference vectors of GBSSI and IbSBEII and introduced them into sweetpotato genome via Agrobacterium-mediated gene transformation. The endogenous GBSSI expression was inhibited by dsRNA of GBSSI in 73 % of transgenic plants giving rise to the storage tubers containing amylopectin but not amylose. On the other hand, all sweetpotato plants transformed with dsRNA of IbSBEII contained a larger amount of amylose than the non-transgenic control (up to 25% compared to 10% in the controls). The RNA interference (RNAi) is effectively inhibited the gene expression in thestarch metabolic pathway and modified the characteristics of starch in sweetpotato.

Xanthine dehydrogenase (XDH), a classic enzyme involved in purine catabolism, can catalyze the formation of redox-signaling reactive oxygen and nitrogen species such as superoxide and nitric oxide. We generated transgenic plants of Arabidopsis in which XDH was knocked out by introduction of hairpin RNA-expression vector. Expression analysis by reverse transcription-PCR and in-gel staining of XDH activity revealed that transgenic lines efficiently suppressedXDH expression at the transcriptional level, demonstrating that RNA interference was successfully induced. XDH-suppressed transgenic lines exhibitedincreased biomass production during the growth of seedlings.

Opium poppy (Papaver somniferum L.) is one of the most important medicinal plants, which is used as a sole commercial source of narcotic analgesic, morphine. The transformant of opium poppy we have established by infection of Rhizobium rhizogenes (formerly Agrobacterium rhizogenes) strain MAFF03-01724 showed aberrant morphology and altered opium alkaloid composition. The major alkaloid produced by this transformant was thebaine (16.3%, opium dry weight) instead of morphine. It is likely that this 'thebaine poppy' phenotype was caused by the integration of T-DNA(s) into the poppy genome DNA, and their inserted loci are of great interest. To gain an insight into the mechanism of nonnarcotic thebaine accumulation for the further approach toward the creation of 'codeine poppy' which produces codeine as a major alkaloid, the genetical and morphological analyses on the transformant was carried out. Here we report the results of the detailed analysis on the T-DNA inserted loci of T0 transfromant and the correlation between opium alkaloid composition and segregated T-DNA integration pattern in the self-pollinated T1 transformants.

The risk from genetically modified (GM) plants results from the possibility of gene contamination producing adverse effects on biological diversity by introducing herbicide or insect resistance into related plants or weeds (NAS 2002). The concern about the leakage of genes from GM plants into the environment has primarily focused on pollen that could be wind-borne for long distances. During the period of fisk assessment in Japan, physical containment is applied as a measure of reducing gene flow via the dispersal of pollen from GM plants into the surrounding environment In this study, we tried to estimate the effect of physically contained greenhouse covered by 1-mm fine mesh to reduce pollen dispersal by researching cross pollination rate between non-GM yellow maize in a greenhouse and silver maize outside the greenhouse.

In our previous work in transcriptional regulation of sugar, expression of genes encoding putative glycosyl hydrolases in Arabidopsis was induced by sugar starvation. They were annotated as b-galactosidase (At5g56870), ${\beta}-xylosidase$ (At5g49360) and ${\beta}-glucosidase$ (At3g60140), which belong to glycosyl hydrolase family that has a catalytic domain of polysaccharides. From the primary structure of deduced amino acid sequence, they were predicted to localize to cell wall. Further investigation of these cell wall hydrolases implicated that cell wall polysaccharides provide metabolizable sugars to nutrient allocation under sugar starvation.