Switchgrass is a wild-perennial plant in North America, and rich in cellulose, making it attractive as a source for cellulosic ethanol. Especially, ethanol which is made from switchgrass produce more 540% energy better than the others. The objectives of this study were to examine the concentrations of phenolic compounds, monosaccharides and disaccharides which detected in some different part (upper, center, lower) of 34 species of switchgrasses. The total average of phenolic compound concentration was 4017.48 ㎍/g. Whereas it's concentration in the upper part was shown the highest (6669.09㎍/g) and the lower part was the lowest (1916.30㎍/g). The No.23 has the highest concentration of phenolic compounds but No.20 have the lowest concentration. In saccharides analysis, only arabinose and glucose are detected. The total average of monosaccharides and disaccharides concentration was 206284.75 ㎍/g. Whereas its concentration in the upper part was shown the highest (269738.18㎍/g) and the lower part was the lowest (167567.53㎍/g). The No.30 has the highest concentration of saccharides but No.2 have the lowest concentration. The obtained results shows that switchgrass are good sources of bio-ethanol and the upper part is the best among them.

Superoxide dismutases (SOD) are metalloenzymes that convert O2- to H2O2. Rehmannia glutinosa is highly tolerant to paraquat-induced oxidative stress. The primary objective of this study was to characterize regulation of SOD gene expression in R. glutinosa in response to oxidative stresses and hormones. A full-length putative SOD clone (RgCu-ZnSOD1) was isolated from the leaf cDNA library of R. glutinosa using an expressed sequence tag clone as a probe. RgCu-ZnSOD1 cDNA is 777 bp in length and contains an open reading frame for a polypeptide consisted of 152 amino acid residues. The deduced amino acid sequence of the clone shows highest sequence similarity to the cytosolic Cu-ZnSODs. The two to three major bands with several minor ones on the Southern blots indicate that RgCu-ZnSOD1 is a member of a small multi-gene family. RgCuZnSOD1 mRNA was constitutively expressed in the leaf, flower and root. The expression of RgCu-ZnSOD1 mRNA was increased about 20% by wounding and paraquat, but decreased over 50% by ethylene and GA3. This result indicates that the RgCu-ZnSOD1 expression is regulated differentially by different stresses and phytohormones at the transcription level. The RgCu-ZnSOD1 sequence and information on its regulation will be useful in investigating the role of SOD in the paraquat tolerance of R. glutinosa.

Rehmannia glutinosa shows a high level of resistance to the non-selective herbicide paraquat. To characterize the antioxidant enzyme system of R. glutinosa, we comparatively examined the responses of antioxidant enzymes to UV, wounding and a general elicitor yeast extract in R. glutinosa and soybean. The levels of enzyme activities of the two plant species were drastically different between those per fresh weight (general activity) and per protein (specific activity) bases. The general activities of superoxide dismutase (SOD), peroxidase (POX), catalase (CAT), and glutathione reductase (GR) were lower, but that of ascorbate peroxidase (APX) was higher in R. glutinosa than in soybean. The specific activities of the enzymes, however, were about two- to seven-fold higher in R. glutinosa than in soybean, except that of CAT, which was about 12-fold higher in soybean. The general and specific enzyme activities of R. glutinosa relative to those of soybean showed a consistent increase in responses to the stresses only in SOD. The specific activities of SOD and APX were higher in R. glutinosa in all stress treatments. The results might suggest a relatively higher contribution of SOD and APX to the stress tolerance.