Leaf water and osmotic potential, chlorophyll content, photosynthetic rate, and electrolyte leakage were measured to evaluate tolerance to water stress in wild-type (WT) and transgenic tobacco plants (TR) expressing copper/zink superoxide dismutase (CuZnSOD) and ascorbate peroxidase (APX) in chloroplasts. Leaf water potential of both WT and TR plants decreased similarly under water stress condition. However, leaf osmotic potential of TR plants more negatively decreased in the process of dehydration, compared with WT plants, suggesting osmotic adjustment. Stomatal conductance (Gs) in WT plants markedly decreased from the Day 4 after withholding water, while that in TR plants retained relatively high values. Relatively low chlorophyll content and photosynthetic rate under water stress were shown in WT plants since 4th day after treatment. In particular, damage indicated by electrolyte leakage during water stress was higher in WT plants than in TR plants. On the other hand, SOD and APX activity was remarkably higher in TR plants. These results indicate that transgenic tobacco plants expressing copper/zink superoxide dismutase (CuZnSOD) and ascorbate peroxidase (APX) in chloroplasts improve tolerance to water stress.

1. 서론
 2. 재료 및 방법
  2.1. 식물재료
  2.2. 실험방법
 3. 결과
  3.1. 잎의 수분관계
  3.2. 광합성률과 엽록소 함량
  3.3. 항산화효소 활성
 4. 결론
 감사의 글
 REFERENCES

• 박용목(청주대학교 생명과학과, Department of Life Science, Cheongju University) | Yong Mok Park Corresponding author