Recovery of Basta-resistant Sedum erythrostichum via Agrobacterium-mediated transformation

Sedums are used as groundcover, in rock gardens and flower borders, and for greening the top floor of buildings, cottages, and thatched roofs. In this study, Agrobacterium-mediated genetic transformation of Sedum erythrostichum was studied by introducing a herbicide-resistant gene (phosphinothricin-N-acetyl-transferase) and a reporter gene (#-glucuronidase, GUS). Following co-cultivation with Agrobacterium on MS medium supplemented with 0.5 mg/l !-naphthaleneacetic acid (NAA) and 2 mg/l 6-benzylaminopurine (BA) for 3 days, leaf segments were transferred onto medium containing 300 mg/l cefotaxime. When adventitious shoots developed directly near the margins of explants after 3 weeks, they were transferred to selection medium with 25 mg/l kanamycin. Of a total of 640 infected leaf explants, 24 (3.75%) produced kanamycin-resistant adventitious shoots; of these, 2.5% were GUS-positive. Transgenic plantlets were confirmed using polymerase chain reaction, Southern, and Northern analyses. Ninety-four percent of the transgenic plantlets were successfully transferred to soil and produced flowers. All GUS-positive transgenic plants were strongly resistant to Basta (phosphinothricin at 200 mg/l) after spraying.     

Transgenic herbicide- and disease-tolerant carrot (Daucus carota L.) plants obtained through Agrobacterium-mediated transformation

. Transgenic carrot (Daucus carota L.) plants expressing a rice thaumatin-like protein (tlp), phosphinothricin acetyltransferase (bar) and the hygromycin phosphotransferase (hpt) genes were obtained by Agrobacterium-mediated transformation. Petiole and hypocotyl segments of three carrot cultivars were used as the explant sources. Following infection, selection was achieved on Murashige and Skoog medium with 1 mg/l phosphinothricin or 25 mg/l hygromycin B, which was increased after 2 weeks to 10 mg/l phosphinothricin and 100 mg/l hygromycin B. The presence of the tlp and bar transgenes was confirmed by polymerase chain reaction and Southern blot analyses, and the expression of the thaumatin-like protein was demonstrated by Western blot analysis. Among 45 primary transformants, 13 were selected for assessment of herbicide and/or disease tolerance. The transgenic plants showed varying levels of tolerance to the herbicide phosphinothricin, depending on the transformation events in different lines. Four transgenic lines also showed significantly enhanced tolerance to the foliar and root pathogen Botrytis cinerea or Sclerotinia sclerotiorum when inoculated under controlled environment conditions. Two lines had significantly enhanced tolerance to the herbicide phosphinothricin as well as to both pathogens. These results demonstrate the feasibility of introducing two potentially useful agronomic traits into carrot through genetic engineering.     

<Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated transformation of a doubled haploid line of cabbage

Doubled haploid lines, which have high levels of genetic uniformity, are suitable for physiological or genetic studies. We established a transformation system using a doubled haploid line of cabbage. Hypocotyl explants that had been precultured for 3 days on Murashige and Skoog medium containing 50 µM acetosyringone were inoculated and cocultured with Agrobacterium tumefaciens strain LBA4404 (pIG121Hm) for 3 days. Kanamycin-tolerant shoots were regenerated onto shoot induction medium 3 months after Agrobacterium inoculation. The transformation efficiency was about 3% under optimal conditions. The segregation pattern of the self-pollinated transformant that carried one copy of the introduced transgene revealed that the #-glucuronidase gene was inherited in a 3:1 ratio.     

Flow cytometric analysis and molecular characterization of Agrobacterium tumefaciens-mediated transformants of Medicago truncatula

Leaf explants from leaflets collected from either in vivo grown or in vitro grown seedlings of Medicago truncatula genotype R108-1 were co-cultivated with bacterial cells of Agrobacterium tumefaciens strains EHA105 or C58pMP90. Each of these strains was carrying the pCambia 1390 plasmid harbouring a hygromycin resistance gene cassette. Explants were then incubated on a medium containing 10 mg/l hygromycin and 800 mg/l augmentin to suppress Agrobacterium growth, and subcultured 4–5 times every 2 weeks for the proliferation of calli. After 8–10 weeks, callusing explants were transferred to hormone-free medium with 10 mg/l hygromycin and 400 mg/l augmentin for shoot regeneration. After rooting, a total of about 300 putative transformants were grown into plantlets, transferred to soil, acclimatized, and then moved to the greenhouse. Of these, a total of 43 independent PCR positive primary transformants and their T1 and T2 progeny were subjected to flow cytometric analysis, to assessing their trueness-to-type, as well as to southern blot analysis.     

Efficient Agrobacterium-mediated transformation of Arabidopsis thaliana using the bar gene as selectable marker

Summary We have established an efficient Agrobacterium-mediated transformation procedure for Arabidopsis thaliana genotype C24 using the chimeric bialaphos resistance gene (bar) coding for phosphinothricin acetyltransferase (PAT). Hypocotyl explants from young seedlings cocultivated with agrobacteria carrying a bar gene were selected on shoot-inducing media containing different concentrations of phosphinothricin (PPT) which is an active component of bialaphos. We found that 20 mg/l of PPT completely inhibited the control explants from growing whereas the explants transformed with the bar gene gave rise to multiple shoots resistant to PPT after 3 weeks under the same selection conditions. The transformation system could also be applied to root explants. Resulting plantlets could produce viable seeds in vitro within 3 months after preparation of the explants. The stable inheritance of the resistance trait, the integration and expression of the bar gene in the progeny were confirmed by genetic tests, Southern analysis and PAT enzyme assay, respectively. In addition, the mature plants in soil showed tolerance to the herbicide Basta.Abbreviations bar bialaphos resistance gene - CIM callus-inducing medium - DTNB 5,5-dithiobis(2-nitrobenzoic acid) - GM germination medium - HPT hygromycin phosphotransferase - MS Murashige and Skoog salts - NPTII neomycin phosphotransferase II - PAT phosphinothricin acetyltransferase - PPT phosphinothricin - SIM shoot-inducing medium     

Efficient plant regeneration via direct organogenesis and Agrobacterium tumefaciens-mediated genetic transformation of Picrorhiza kurroa: an endangered medicinal herb of the alpine Himalayas

Picrorhiza kurroa Royle ex. Benth. is a medicinal herb of immense therapeutic value with restricted geographic distribution. Efficient plant regeneration via direct organogenesis and Agrobacterium tumefaciens-mediated genetic transformation was developed for this plant. Multiple shoot bud induction was achieved from leaf explants cultured in Gamborg??s B₅ medium containing 3?% (w/v) sucrose, 3?mg/l kinetin and 1?mg/l indole-3-butyric acid. More than 90?% of leaf explants formed shoot buds leading to whole plant regeneration. An Agrobacterium-mediated genetic transformation protocol was developed using A. tumefaciens strain GV3101 harboring binary vector pCAMBIA1302 containing the green fluorescent protein and hygromycin phosphotransferase genes. Leaf explants precultured for 2?d were the most suitable for co-cultivation with Agrobacterium and transformation efficiency was enhanced with 200???M acetosyringone. Putative transformants were selected using media containing 15?mg/l hygromycin. Transformation was verified by detection of the green fluorescent protein using fluorescence microscopy and by polymerase chain reaction. Approximately 56?% of the explants were transformed with an average of 3.4?±?0.4 transgenic plantlets per explant. An efficient regeneration and transformation protocol thus developed enabling a fresh perspective of metabolic engineering in P. kurroa using an Agrobacterium-mediated transformation. This is the first report of direct organogenesis from leaf explants and genetic transformation of P. kurroa.     

Agrobacterium tumefaciens-mediated transformation of Elatior Begonia (Begonia×hiemalis Fotsch)

We report a method for Agrobacterium-mediated transformation of Elatior Begonia (Begonia×hiemalis Fotsch). Young leaf discs were infected with Agrobacterium tumefaciens strains AGL0 and LBA4404. Each strain has a binary vector plasmid, pIG121Hm that includes the β-glucuronidase (GUS) gene with an intron as a reporter gene, and both the neomycin phosphotransferase II and the hygromycin phosphotransferase genes as selection markers. Explants were cultured on modified MS medium supplemented with 1.0 mg/l BA, 0.5 mg/l IAA, 300 mg/l ticarcillin, and either 100 mg/l kanamycin and 5 mg/l hygromycin, or 300 mg/l kanamycin for selection and regeneration. Out of 500 explants infected with AGL0, 16 plantlets were regenerated, and out of 628 explants infected with LBA4404, two plantlets were regenerated after 4 months of culture. Transformation was confirmed by Southern blot analysis of the GUS gene and by histochemical assays of GUS activity in plant tissues. Ten in vitro transgenic plants were obtained from AGL0 infected explants only.     

<Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated production of transgenic plants of<Emphasis Type="Italic"> Muscari armeniacum</Emphasis> Leichtl. ex Bak.

A system for the production of transgenic plants has been developed for the Liliaceous ornamental plant Muscari armeniacum Leichtl. ex Bak via Agrobacterium-mediated transformation of embryogenic cultures. Leaf-derived embryogenic cultures were co-cultivated with each of three A. tumefaciens strains, all of which harbored the binary vector carrying the neomycin phosphotransferase II (nptII), hygromycin phosphotransferase (hpt) and intron-containing #-glucuronidase (gus-intron) genes in the T-DNA region. Following co-cultivation, the embryogenic cultures were cultured on a medium containing 500 mg l^-1 cefotaxime for 1 week followed by a medium containing 75 mg l^-1 hygromycin in addition to cefotaxime. After 4-5 weeks, several hygromycin-resistant (Hyg^r) cell clusters were produced from the co-cultivated embryogenic cultures. The highest efficiency of production of Hyg^r cell clusters was obtained when embryogenic cultures were inoculated with A. tumefaciens EHA101/pIG121Hm in the presence of 100 µM acetosyringone (AS) and 0.1% (v/v) of a surfactant (Tween20) followed by co-cultivation in the presence of 100 µM AS. Hyg^r embryogenic cultures developed into complete plants via somatic embryogenesis, and most of them were verified to be transgenic by GUS histochemical assay and polymerase chain reaction analysis. Southern blot analysis revealed the integration of one to five copies of the transgene into the genome of transgenic plants, but most of them had one or two copies.     

Importance of co-cultivation medium pH for successful Agrobacterium-mediated transformation of Lilium × formolongi

An efficient system for Agrobacterium-mediated transformation of Lilium × formolongi was established by preventing the drastic drop of pH in the co-cultivation medium with MES. Meristematic nodular calli were inoculated with an overnight culture of A. tumefaciens strain EHA101 containing the plasmid pIG121-Hm which harbored intron-containing β-glucuronidase (GUS), hygromycin phosphotransferase (HPT), and neomycin phosphotransfease II (NPTII) genes. After three days of co-cultivation on 2 g/l gellan gum-solidified MS medium containing 100 μM acetosyringone, 30 g/l sucrose, 1 mg/l picloram and different concentrations of MES, they were cultured on the same medium containing 12.5 mg/l meropenem to eliminate Agrobacterium for 2 weeks and then transferred onto medium containing the same concentration of meropenem and 25 mg/l hygromycin for selecting putative transgenic calli. Transient GUS expression was only observed by adding MES to co-cultivation medium. Hygromycin-resistant transgenic calli were obtained only when MES was added to the co-cultivation medium especially at 10 mM. The hygromycin-resistant calli were successfully regenerated into plantlets after transferring onto picloram-free medium. Transformation of plants was confirmed by histochemical GUS assay, PCR analysis and Southern blot analysis.     

Mass production of Siberian ginseng plantlets through large-scale tank culture of somatic embryos

Siberian ginseng (Eleutherococcus senticosus) is an endangered medicinal woody plant that is distributed throughout the cold regions of northeast Asia. Its propagation is very difficult. In the present article we describe the mass production of Siberian ginseng plantlets by large-scale tank cultures. High-frequency somatic embryogenesis was achieved through suspension culture of embryogenic cells in Murashige and Skoog (MS) liquid medium lacking 2,4-D. About 12,000 embryos were produced per 500-ml flask after 4 weeks of culture. Cotyledonary somatic embryos were germinated, and these converted into plantlets following a pretreatment of the embryos with gibberellic acid (20 µM) and subsequent transfer to a 10-l plastic tank. Low-strength MS medium (1/5-, 1/3-strength) was more effective than its full-strength counterpart for the production of plantlets. After 40 days, an initial 35-g inoculum of embryos was converted to 567 g fresh mass of plantlets in 1/3-strength MS medium. This result indicates that an efficient protocol for the mass production of Siberian ginseng plantlet can be achieved by tank culture of somatic embryos. The Siberian ginseng plantlets produced can be used as a source of medicinal raw materials.     

An efficient regeneration system and <Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated transformation of Chinese upland rice cultivar Handao297

A highly efficient tissue culture system and Agrobacterium-mediated transformation protocol for Chinese upland rice cultivar Handao297 has been established with mature embryos as explants. Up to 81.2% of mature embryos were induced to regenerate good-quality calli on NB medium (a medium combining N6 macronutrient components and B5 micronutrient and organic components) containing 3 mg/l 2,4-dichlorophenoxyacetic acid in 10 days. More than 80% of the calli were morphogenic within 1 week and regenerated green plantlets within 1 month on Murashige and Skoog medium supplemented with 0.5 mg/l 6-benzyladenine, 0.5 mg/l kinetin, 1 mg/l zeatin, 0.5 mg/l thidizazuron (TDZ), 0.5 mg/l naphthaleneacetic acid, 0.15 mg/l indoleacetic acid, and 0.15 mg/l indolebutyric acid. This tissue culture system was suitable for Agrobacterium-mediated transformation of upland rice Handao297. Furthermore, some important factors affecting transformation frequency were investigated with Agrobacterium strain AGL1 containing the plasmid pCAMBIA1381. The addition of 30 mg/l hygromycin B followed by 60 mg/l hygromycin B to the selection induction medium facilitated the revival of calli from selection and reduced false positive calli. Hygromycin B at 10 mg/l was most effective in suppressing non-transgenic callus growth in the differentiation medium. The addition of TDZ to the differentiation medium promoted the morphogenesis of calli and facilitated the generation of adventitious shoots by five to tenfold in comparison to medium without TDZ.     

Plant regeneration and genetic transformation of C. canadensis: a non-model plant appropriate for investigation of flower development in Cornus (Cornaceae)

Key message

Efficient Agrobacterium -mediated genetic transformation for investigation of genetic and molecular mechanisms involved in inflorescence architectures in Cornus species.

Abstract

Cornus canadensis is a subshrub species in Cornus, Cornaceae. It has recently become a favored non-model plant species to study genes involved in development and evolution of inflorescence architectures in Cornaceae. Here, we report an effective protocol of plant regeneration and genetic transformation of C. canadensis. We use young inflorescence buds as explants to efficiently induce calli and multiple adventitious shoots on an optimized induction medium consisting of basal MS medium supplemented with 1 mg/l of 6-benzylaminopurine and 0.1 mg/l of 1-naphthaleneacetic acid. On the same medium, primary adventitious shoots can produce a large number of secondary adventitious shoots. Using leaves of 8-week-old secondary shoots as explants, GFP as a reporter gene controlled by 35S promoter and hygromycin B as the selection antibiotic, a standard procedure including pre-culture of explants, infection, co-cultivation, resting and selection has been developed to transform C. canadensis via Agrobacterium strain EHA105-mediated transformation. Under a strict selection condition using 14 mg/l hygromycin B, approximately 5 % explants infected by Agrobacterium produce resistant calli, from which clusters of adventitious shoots are induced. On an optimized rooting medium consisting of basal MS medium supplemented with 0.1 mg/l of indole-3-butyric acid and 7 mg/l hygromycin B, most of the resistant shoots develop adventitious roots to form complete transgenic plantlets, which can grow normally in soil. RT-PCR analysis demonstrates the expression of GFP transgene. Green fluorescence emitted by GFP is observed in transgenic calli, roots and cells of transgenic leaves under both stereo fluorescence microscope and confocal microscope. The success of genetic transformation provides an appropriate platform to investigate the molecular mechanisms by which the various inflorescence forms are developed in Cornus plants.     

Transgenic silver birch (Betula pendula) expressing sugarbeet chitinase 4 shows enhanced resistance to Pyrenopeziza betulicola

A sugar beet chitinase gene driven by the (42) CaMV 35S promoter was introduced into silver birch (Betula pendula) through Agrobacterium-mediated transformation. Transgenic shoots were regenerated and grown on WPM medium supplemented with 150 mg/ml kanamycin. From a total of 220 explants, 52 transgenics were obtained and 13 transgenic lines were randomly taken for molecular analysis to confirm the presence of the introduced sugar beet chitinase 4 cDNA by polymerase chain reaction and Southern hybridisation. All 13 transgenic lines were confirmed to contain the gene and further characterised. Northern blot analysis of total RNA indicated that the transgenic lines differed with respect to the steady-state levels of chitinase mRNA. Transgenic lines with high levels of mRNA of chitinase 4 cDNA consistently showed higher levels of resistance to Pyrenopeziza betulicola than transgenics with intermediate or low mRNA levels or a non-transgenic control plant. This report demonstrates that the constitutive expression of this gene in transgenic birch lines increased the resistance of birch against the leaf spot fungus P. betulicola.     

Sonication-assisted Agrobacterium-mediated transformation of soybean [Glycine max (L.) Merrill] embryogenic suspension culture tissue

Successful transformation of plant tissue using Agrobacterium relies on several factors including bacterial infection, host recognition, and transformation competency of the target tissue. Although soybean [Glycine max (L.) Merrill] embryogenic suspension cultures have been transformed via particle bombardment, Agrobacterium-mediated transformation of this tissue has not been demonstrated. We report here transformation of embryogenic suspension cultures of soybean using “Sonication-Assisted Agrobacterium-mediated Transformation” (SAAT). For SAAT of suspension culture tissue, 10–20 embryogenic clumps (2–4 mm in diameter) were inoculated with 1 ml of diluted (OD_600nm 0.1–0.5) log phase Agrobacterium and sonicated for 0–300 s. After 2 days of co-culture in a maintenance medium containing 100 μM acetosyringone, the medium was removed and replaced with fresh maintenance medium containing 400 mg/l Timentin^?. Two weeks after SAAT, the tissue was placed in maintenance medium containing 20 mg/l hygromycin and 400 mg/l Timentin^?, and the medium was replenished every week thereafter. Transgenic clones were observed and isolated 6–8 weeks following SAAT. When SAAT was not used, hygromycin-resistant clones were not obtained. Southern hybridization analyses of transformed embryogenic tissue confirmed T-DNA integration. Received: 22 August 1997 / Revision received: 22 October 1997 / Accepted: 11 November 1997     

Agrobacterium-mediated transformation of protocorm-like bodies in Cymbidium

Genetically transformed plants of Cymbidium were regenerated after cocultivating protocorm-like bodies (PLB) with Agrobacterium tumefaciens strain EHA101 (pIG121Hm) that harbored genes for β-glucuronidase (gus), hygromycin phosphotransferase (hpt) and neomycin phosphotransferase II (nptII). PLB of three genotypes maintained in liquid new Dogashima medium (NDM), were subjected to transformation experiments. The PLB inoculated with Agrobacterium produced secondary PLB, 4 weeks after transfer onto 2.5 g L⁻¹ gellan gum-solidified NDM containing 10 g L⁻¹ sucrose, 20 mg L⁻¹ hygromycin and 40 mg L⁻¹ meropenem. Transformation efficiency was affected by genotype and the presence of acetosyringone during cocultivation. The highest transformation efficiency was obtained when PLB from the genotype L4 were infected and cocultivated with Agrobacterium on medium containing 100 μM acetosyringone. Transformation of the hygromycin-resistant plantlets regenerated from different sites of inoculated PLB was confirmed by histochemical GUS assay, PCR analysis and Southern blot hybridization.     

Transformed T0 orchardgrass (Dactylis glomerata L.) plants produced from highly regenerative tissues derived from mature seeds

A highly efficient and reproducible transformation system for orchardgrass (Dactylis glomerata L. cv. Rapido, 2n=42=28) was established using microprojectile bombardment of highly regenerative, green tissues derived from mature seeds. These tissues, induced from embryogenic callus, were bombarded with a mixture of three plasmids containing the hygromycin phosphotransferase (hpt), phosphinothricin acetyltransferase (bar) and #-glucuronidase (uidA; gus) genes. From 147 individual explants bombarded, 11 independent hygromycin-resistant lines (7.5%) were obtained after an 8- to 16-week selection period using 30-50 mg/l hygromycin B. Of the 11 independent lines, ten (91%) were regenerable. The presence and integration of the transgene(s) were assessed using PCR and DNA blot hybridization. Coexpression frequency of the three transgenes (hpt/bar/uidA) in T₀ plants was 20%, and of two transgenes, either hpt/bar or hpt/uidA, 45-60%. Due to greenhouse conditions optimized for the growth of other species, T₁ seed has not been obtained from these plants. While the inability to analyze progeny plants precludes the conclusive demonstration of stable transformation, the results of all molecular and biochemical analyses of T₀ plants are consistent with the production of stably transformed plants. Frequent change in ploidy level was observed in transformed T₀ orchardgrass plants. Plants from only three of the ten independent lines analyzed had the normal tetraploid number of chromosomes (2n=42=28), while plants from seven lines (70%) were octaploid (2n=82=56). The octaploid plants had abnormal morphological features, such as narrower, thicker and more upright leaves.     

Optimization of in vitro micropropagation and regeneration for Populus × interamericana and Populus × euramericana hybrids (P. deltoides, P. trichocarpa, and P. nigra)

A rapid and efficient micropropagation method has been established for six European poplar cultivars of economic interest - four Populus 2 interamericana and two Populus 2 euramericana. Using a three-step procedure, we were able to regenerate plantlets from callus and acclimate them within 4 months. In the first step, callogenesis was induced when explants were cultured for 25 days on culture medium supplemented with 10 µM !-naphthaleneacetic acid and 5 µM N⁶(2-isopentenyl)adenine. Bud regeneration followed by shoot elongation was then obtained from callus tissue by combining the cytokinin-like compound thidiazuron with the surfactant Pluronic F-68 at concentrations adjusted for each cultivar. The usefulness of this procedure in the area of genetic engineering is discussed.     

Growth regulator pretreatment improves somatic embryogenesis from leaves of squash (Cucurbita pepo l.) and melon (Cucumis melo l.)

Leaf explants of squash (Cucurbita pepo L.) and melon (Cucumis melo L.) were pretreated initially with 113.1, 226.2 or 452.4 µM 2,4-dichlorophenoxyacetic acid (2,4-D), 46.5, 93 or 186 µM kinetin or a combination of both at the above concentrations, for 6, 24 or 48 h. After pretreatment, explants were transferred to an agar-solidified medium that was not supplemented with growth regulators or to a species-specific standard induction medium. Control explants from each species were incubated directly on the species-specific standard induction medium. Initial pretreatment of squash explants with 186 µM kinetin and of melon explants with 226.2 µM 2,4-D for 48 h significantly promoted the formation of somatic embryos which developed further to the torpedo-shape stage and germinated. Under these conditions at least four plants can be regenerated per square centimeter of explant surface, thus achieving an increase over non-pretreated cultures of 143% and 130% for squash and melon, respectively.     

Chromosome number stability and mitotic activity of cryopreserved Hypericum perforatum L. meristems

Meristems of in vitro-grown Hypericum perforatum L. plants were precultured for 3, 10, or 14 days in the presence of 0.5 M mannitol, or 0.076 µM or 0.76 µM abscisic acid, in RM basal liquid culture medium supplemented with 0.5 mg/l 6-benzylaminopurine and subsequently subjected to cryopreservation by the slow freezing method. The survival rate - determined as the percentage of meristems capable of differentiating plantlets - varied between 10% and 48%. Chromosome number stability of the cryopreserved meristems was determined by chromosome counting. The mitotic index of the control did not significantly differ from that of the treated samples.     

Production of herbicide-resistant transgenic <Emphasis Type="Italic">Panax ginseng</Emphasis> through the introduction of the phosphinothricin acetyl transferase gene and successful soil transfer

Herbicide-resistant transgenic Panax ginseng plants were produced by introducing the phosphinothricin acetyl transferase (PAT) gene that confers resistance to the herbicide Basta (bialaphos) through Agrobacterium tumefaciens co-cultivation. Embryogenic callus gathered from cotyledon explants of P. ginseng were pre-treated with 0.5 M sucrose or 0.05 M MgSO(4 )before Agrobacterium infection. This pre-treatment process markedly enhanced the transient expression of the beta-glucuronidase (GUS) gene. Embryogenic callus was initially cultured on MS medium supplemented with 400 mg/l cefotaxime for 3 weeks and subsequently subcultured five times to a medium containing 25 mg/l kanamycin and 300 mg/l cefotaxime. Somatic embryos formed on the surfaces of kanamycin-resistant callus. Upon development into the cotyledonary stage, these somatic embryos were transferred to a medium containing 50 mg/l kanamycin and 5 mg/l gibberellic acid to induce germination and strong selection. Integration of the transgene into the plants was confirmed by polymerase chain reaction and Southern analyses. Transfer of the transgenic ginseng plantlets to soil was successfully accomplished via acclimatization in autoclaved perlite. Not all of the plantlets survived in soil that had not been autoclaved because of fungal infection, particularly in the region between the roots and leaves. Transgenic plants growing in soil were observed to be strongly resistant to Basta application.