African Journal of

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12227

Full Length Research Paper

Over expression of CuZn superoxide dismutase (CuZn SOD) and ascorbate peroxidase (APX) in transgenic sweet potato enhances tolerance and recovery from drought stress

  Yan-Yuan Lu1,2, Xi-Ping Deng1* and Sang-Soo Kwak3  
Email: [email protected]

  •  Accepted: 01 November 2010
  •  Published: 06 December 2010



To understand the antioxidant stress of transgenic sweet potato containing elevated Cu/Zn superoxide dismutase (Cu/Zn SOD) and ascorbate peroxidase (APX) in chloroplasts, we analyzed plant growth, yield, water status, photosynthetic activity and several antioxidant enzyme activities under drought and post-drought re-watering conditions. Three water stress regimes - no, moderate and severe water stress - were applied. Our results indicated that the number of transgenic plants (TS) was a function of water deficit and recovery period. Compared with non-transgenic plants (NS), the expression of antioxidant enzymes (SOD, APX and CAT) in transgenic plants was profoundly increased under drought stress and rewatering periods. Transgenic plants exhibited better growth, photosynthetic activity (Fv/Fm) and water status under drought stress, but tuberization was poor. Compared with NS plants, TS plants exhibited low levels of malondialdehyde (MDA) and electrolyte leakage (EL). In addition, TS plants recovered faster upon release from drought stress. These results showed that expression of Cu/Zn SOD and APX in chloroplasts of sweet potato enhanced drought resistance and capacity for recovery from drought stress. However, tuber formation in TS plants was constrained by drought stress.


Key words: Transgenic sweet potato, antioxidant enzyme, drought, recovery.



Abbreviations: ROS, Reactive oxygen species; SOD, superoxide dismutase;APX, ascorbate peroxidase; CAT, catalase; POD, peroxidase; MV, methyl viologen;NS, non-transgenic plants; PEG, polyethylene glycol; RWC, relative water content;MDA, malondialdehyde; TBARS, 2-thiobarbituric acid-reactive substances; NBT,nitro blue tetrazolium; TS, transgenic plants; EL, electrolyte leakage.