Transcript Document

Lecture14
Stress senescence tolerant plants
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
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
Oxidative stress tolerant plants
• Stress reduced if the level of oxidized
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•
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)
Oxidation of GSH to GSSH and simultaneous
reduction of organic peroxide to an organic alcohol,
catalyzed by glutathione peroxidase
Oxidative stress tolerant plants
• Transgenic tobacco plants that express
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•
•
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