Stress senescence tolerant plants

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Lecture14

• Stress senescence tolerant plants

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Development of oxidative stress tolerant plants

• Under oxidative stress the enzyme superoxide
  dismutase detoxifies super oxide anion to
  hydrogen peroxide and then to water and oxygen

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Development of oxidative stress tolerant plants

• tobacco plants transformed with a superoxide
  dismutase gene
• under the control of the 35S promoter from
  cauliflower mosaic virus
• reduced oxygen radical damage under stress
  conditions compared with control plants

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Oxidative stress tolerant plants

• Stress reduced if the level of oxidized
  glutathione within a plant is increased
• a tobacco cDNA encoding an enzyme with both
  glutathione S-transferase and glutathione
  peroxidase activity was isolated
• Glutathione peroxidase catalyzes the conversion
  of glutathione (GSH) to oxidized glutathione
  (GSSG) by reacting with organic peroxides and
  reducing them to organic alcohols (Fig.2)

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Oxidation of GSH to GSSH and simultaneous
reduction of organic peroxide to an organic
alcohol, catalyzed by glutathione peroxidase
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Oxidative stress tolerant plants

• Transgenic tobacco plants that express
  glutathione peroxidase were created
• using the isolated cDNA under the control of the
  35S promoter
• the construct introduced into plants with a
  binary Ti plasmid system
• transformed plant had approximately twice the
  level of enzyme activity found in non transformed
  plants

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