Transformed plants with elevated levels of chloroplastic SOD are not more resistant to superoxide toxicity

Plant Mol Biol. 1990 Apr;14(4):501-11. doi: 10.1007/BF00027496.


The petunia nuclear gene which encodes the chloroplast isozyme of superoxide dismutase, SOD-1, has been fused with an efficient rbcS promoter fragment and 3' flanking region and introduced into tobacco and tomato cells. Transformed plants carrying this chimeric gene have up to 50-fold the levels of SOD-1 which occur in wild-type plants. However, tobacco plants with 30- to 50-fold the normal SOD-1 activity do not exhibit resistance to the light-activated herbicide paraquat. Similarly, tomato plants with 2- to 4-fold increases in SOD-1 do not exhibit tolerance to photoinhibitory conditions known to increase superoxide levels (high light, low temperatures and low CO2 concentrations). Our data indicate that increasing the chloroplastic SOD level in a plant cell is not sufficient to reduce the toxicity of superoxide.

MeSH terms

  • Chloroplasts / drug effects
  • Chloroplasts / metabolism
  • Chloroplasts / radiation effects
  • Cloning, Molecular
  • Gene Expression / drug effects
  • Gene Expression / radiation effects
  • Genetic Engineering
  • Isoenzymes / genetics
  • Isoenzymes / metabolism
  • Light
  • Paraquat / toxicity
  • Plants / drug effects
  • Plants / genetics
  • Plants / metabolism*
  • Plants, Toxic
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Superoxide Dismutase / genetics
  • Superoxide Dismutase / metabolism*
  • Superoxides / metabolism
  • Tobacco / drug effects
  • Tobacco / genetics
  • Tobacco / metabolism
  • Transformation, Genetic


  • Isoenzymes
  • RNA, Messenger
  • Superoxides
  • Superoxide Dismutase
  • Paraquat