|
Summary of Research Projects (Supports in 2003
Fiscal Year)
| Subjects |
Detoxification Mechanisms of Reactive Aldehydes in
Plants |
| Representative researcher |
Yamaguchi University Jun’ichi MANO |
| Joint researcher |
Yamaguchi University Kenji MATSUI |
| Universiteit
Gent Dirk INZÉ |
| Antioxidative defense in
cells is of critical importance in the plant protection against
environmental stress. We have recently identified in Arabidopsis
thaliana a novel enzyme 2-alkenal a,ß-hydrogenase (ALH)
that catalyzes the reduction of the a,ß-unsaturated bond
of 2-alkenals, potent cytotoxins produced from lipid peroxides.
In this study, we aimed at verifying a possible involvement
of the lipid peroxide-derived 2-alkenals (reactive aldehydes)
in the environmental stress-induced damages of plants. When
A. thaliana leaves were oxidatively stressed, production
of crotonaldehyde and acrolein was enhanced. Unlike the case
for oxidatively stressed animal cells, malondialdehyde was
not a major product. Thus, the metabolism of lipid peroxides
differs between plants and animals. Acrolein and crotonaldehyde
inhibited CO2-fixation in isolated chloroplasts strongly,
but did not affect the photosynthetic electron transport
activity. Thus the reactive aldehydes specifically inhibit
Calvin cycle activity, causing photoinhibition. We constructed
three transgenic tobacco lines that overproduced the A.
thaliana ALH. The transgenic plants exhibited higher tolerance to
methyl viologen and to intense light, indicating that ALH
protected leaf cells from oxidative stress. These results
altogether indicate the involvement of the reactive aldehydes
in the photooxidative injury and the significant contribution
of ALH to the antioxidative defense in leaves. |
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