BIOLOGIA PLANTARUM 53 (4): 631-636, 2009 631 Overexpression of the γ-TMT gene in Codonopsis lanceolata E.S. SEONG 1 , B.K. GHIMIRE 2 , E.J. GOH 1 , J.D. LIM 3 , M.J. KIM 1 , I.M. CHUNG 2 and C.Y. YU 1 * Bioherb Research Institute, Kangwon National University, Chunchon 200-701, South Korea 1 Department of Applied Life Science, Konkuk University, Seoul 143-701, South Korea 2 Department of Herbal Medicine Resource, Kangwon National University, Samcheok 245-711, South Korea 3 Abstract A cDNA-encoding γ-tocopherol methyltransferase (γ-TMT) from Arabidopsis thaliana was overexpressed in deoduck (Codonopsis lanceolata L.) to improve the tocopherol composition. Deoduck (T 2 ) containing the γ-TMT transgene was produced by Agrobacterium-mediated transformation. Transgene expression was confirmed by polymerase chain reaction and RNA gel blot analysis. The transgenic plants produced more leaves than control plants. In addition, the transgenic plants showed higher levels of the CSOD, CTRX, CAPX, CNADP + -IDCH, and CSO transcripts and higher SOD-like activity compared with the control plants. Additional key words: antioxidant metabolism, CSOD, deoduck, SOD-like activity. Introduction Codonopsis lanceolata (Campanulaceae) is a perennial medicinal herb distributed in East Asia. Tocopherol- encoding genes, identified in Arabidopsis, can alter the tocopherol composition of seed oils, resulting in improved nutritional and food-quality (Grusak and DellaPenna 1999, Van Eenennaam et al. 2003). While α-tocopherol is the predominant form in leaves, γ-tocopherol and tocotrienols accumulate in the seeds of many plant species (Demurin et al. 1996). The aromatic ring of tocopherol interacts with reactive oxygen species (ROS) and is important in protecting membrane fatty acids from oxidative stress (Fryer 1992, McKersie et al. 1990). Furthermore, tocopherol is necessary for scavenging the ROS that result from photosynthesis (Fryer 1992). Increases in α-tocopherol content in soybean seed have been demonstrated using the γ-TMT gene from Arabidopsis thaliana (At-VTE4) (Kim et al. 2005, Van Eenennaam et al. 2003). The overexpression of the γ-TMT gene has been also reported in Perilla frutescens, lettuce, and Brassica juncea (Rimm et al. 1993, Yusuf and Sarin 2007). The responses of γ-TMT- transgenic deoduck plants to salt and sorbitol stress and methyl viologen treatment were compared with those of the wild type (Brigelius-Flohe and Traber 1999). There have been few reports of the regeneration and morphological characterization of transgenic deoduck plants (Min et al. 1992, Shin and Park 2000, Cho et al. 1999). The role of metal ions, oxidative stress and antioxidant enzymes is related to salinity stress tolerance in maize (Kholova et al. 2009). In the present study, we identified genes whose expression levels change with the overexpression of Arabidopsis thaliana γ-TMT gene in transgenic deoduck plants. We investigated whether the γ-TMT gene can play a role in antioxidant metabolism by regulating the transcription of several marker genes. Materials and methods Agrobacterium-mediated transformation of Codonopsis lanceolata: Agrobacterium tumefaciens strain LBA4404 harboring the binary vector pYB1130, which contains the neomycin phosphotransferase gene (npt II) directed by ⎯⎯⎯⎯ Received 6 April 2008, accepted 15 August 2008. Abbreviations: BA - 6-benzylaminopurine; LB - Luria Bertani; MS - Murashige and Skoog; NAA - α-naphthaleneacetic acid; TAE - Tris-acetate-EDTA. Acknowledgements: This work was supported by the Research Grant from Kangwon National University. And, this work was published by partial financial support of Bioherb Research Institute and the Agriculture & Life Sciences Research Institute, Kangwon National University, Republic of Korea. * Corresponding author; fax: (+82) 33 244 6410, e-mail: cyyu@kangwon.ac.kr