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KMID : 0368419980410030155
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Journal of Plant Biology
1998 Volume.41 No. 3 p.155 ~ p.161
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Activation of Ascorbate-Glutathione Cycle in Arabidopsis Leaves in Response to Aminotriazole
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Kang, Kyong Suk
Lim, Chang Jin/Han, Tae Jin/Kim, Joon Chul/Jin, Chang Duck
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Abstract
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Aminotriazole(AT)-induced changes in growth, hydrogen peroxide content and activities of H_2O_2-scavenging antioxidant enzymes were investigated in the growing leaves of Arabidopsis plants (Arabidopsis thaliana cv Columbia). Catalase activity of rosette leaves was reduced by 65% with an application of 0.1 mM AT (a herbicide known as a catalase inhibitor), whereas the leaf growth and H_2O_2 content were almost unaffected. However, an approximate 1.6 to 2-fold increase in cytosolic ascorbate peroxidase (APX) activity concomitant with a substantial activation of gutathione reductase (GR) (approx. 22% increase) was observed during leaf growth in the presence of 0.1 mM AT. The activity of cytosolic APX in leaves was also increased by 1.8-fold with an application of exogenous 2 mM paraquat (an inducer of H_2O_2 production in plant cells) in the absence of AT. These results collectively suggest that (a) cytosolic APX and GR operate to activate an ascorbate-glutathione cycle for the removal of H_2O_2 under severe catalase deactivatoin, and (b) the expression of APX seems to be regulated by a change of the endogenous H_2O_2 level in leaf cells.
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