Arabidopsis nucleoside diphosphate kinase 2 (AtNDPK2) is an upstream signaling molecule that has been shown to induce stress tolerance in plants. In this study, the AtNDPK2 gene, under the control of a stress-inducible SWPA2 promoter, was introduced into the genome of tall fescue (Festuca arundinacea Schreb.) plants. The induction of the transgene expression mediated by methyl viologen (MV) and NaCl treatments were confirmed by RT-PCR and northern blot analysis, respectively. Under salt stress treatment, the transgenic tall fescue plants (SN) exhibited lower level of H2O2 and lipid peroxidation accumulations than the non-transgenic (NT) plants. The transgenic tall fescue plants also showed higher level of NDPK enzyme activity compared to NT plants. The SN plants were survived at 300 mM NaCl treatment, whereas the NT plants were severely affected. These results indicate that stress-inducible overexpression of AtNDPK2 might efficiently confer the salt stress tolerance in tall fescue plants.

The Salmonella typhimurium cdd gene encoding cytidine deaminase (cyti-dine/2'-deoxycytidine aminohydrolase; EC 3.5.4.5.) was isolated through shotgun clon-ing by complementation of the E. coli odd mutation. By subsequent deletion and sub-cloning from the

The Arabidopsis gene AVP1 encodes a vacuolar H+-translocating inorganic pyrophosphatase (EC3.6.1.1) that functions as an electronic proton pump in the vacuolar membrane and affects growth development and stress responses in plants. This study was conducted to evaluate the molecular properties of the A. thaliana vacuolar H+-pyrophosphatase (AVP1) gene in rice. Incorporation and expression of the transgene was confirmed by PCR and quantitative real-time PCR, respectively. Expression of the AVP1 gene in transgenic rice plants (TRP1 and TRP2) resulted in significantly enhanced tolerance to 100 mM NaCl under greenhouse conditions when compared to control wild-type (WT) rice plants. Augmented AVP1 expression in the transgenic rice plants also affected total biomass and improved ion homeostasis through increased accumulation of Na+ ions in whole tissues when compared to control WT rice plants under high salinity conditions. The Fv/Fm values of transgenic rice plants were higher than those of WT rice plants, even though the values decreased over time in both WT and transgenic (TRP1 to TRP8) rice plants. Furthermore, rice grain yield and biomass of the transgenic rice plants were at least 15% higher based on the culm and root weights and panicle and spikelet numbers when compared to those of the WT rice plants during the farming season in Korea. Thus, these results suggest that ectopic AVP1 expression conferred tolerance and stress resistance to genetically modified transgenic crop plants by improving cellular ion homeostasis against salt conditions, which enhanced the rice yield and biomass under natural conditions in paddy fields.

FLOWERING TIME CONTROL PROTEIN, FPA gene encode RNA Recognition Motif (RRM) domain protein and plays important roles in flowering time control in Arabidopsis. Floral transition is significant for reproductive products in all flowering plants. However, little is known about the functions of Medicago autonomous pathway gene. We had cloned the FPA gene on Medicago based on the sequence similarity of Arabidopsis FPA sequence. The RT-qPCR analysis of MtFPA expression patterns showed that the MtFPA transcripts accumulated ubiquitously in roots, leaves, stems, flowers, and pods. When fused to the green fluorescence protein, MtPFA-GFP was localized in the nucleus as speckle pattern of protoplast from Arabidopsis. To examine the function of MtFPA, 35S::MtFPA transgenic plants were generated in Arabidopsis late flowering mutant background, fpa-2. Overexpression of MtFPA specifically caused early flowering under long day conditions compared with non-transgenic plants. In MtFPA transgenic lines, AtFLC expression were down-regulated whereas the floral integrators, AtFT and AtSOC1 were up-regulated as compare with control plant. As these results, MtFPA suggest that is a functional ortholog of the Arabidopsis and may play an important role in the regulation of flowering transition in Medicago.

FPS (farnesyl diphosphate synthase) plays an essential role in organ development in plants. However, FPS has not previously been identified as a key regulatory enzyme in triterpene biosynthesis. In order to investigate the effect of FPS on ginsenosides biosynthesis, we over-expressed FPS of Centella asiatica (CaFPS) in Panax giseng adventitious roots. PCR analysis showed the integrations of the CaFPS and hygromycin phosphotransferase genes and we ultimately selected three lines. The result of Southern blot analysis demonstrated the introduction of the CaFPS gene into genome of ginseng. In addition, the results of RT-PCR analysis revealed that CaFPS gene overexpression induced an accumulation of its transcription in the ginseng adventitious roots. To determine whether or not the overexpression of the CaFPS gene contributes to the downstream gene expression associated with triterpene biosynthesis, the level of mRNAs was analyzed by real-time PCR. The result showed that no differences were detected in any expression of all genes. To determine quantitatively the content of ginsenosides in transgenic ginseng adventitious roots, HPLC analysis was conducted. The content of total 7 ginsenosides was increased to 1.8, 1.4, and 1.7 times than that of the controls, respectively. This indicated that the overexpression of CaFPS in ginseng adventitious roots causes an increase in ginsenoside content, although down stream genes of FPS gene were suppressed by CaFPS overexpression.