In plants, oxidative stress is one of the major causes of damage as a result of various environmental stresses. Oxidative stress is primarily because of the excessive accumulation of
reactive oxygen species (ROS). The amplification of ROS damage is further stimulated by the accumulation of toxic degradation products, i.e.
aldehydes, arising from reactions of ROS with
lipids and
proteins. Previously, the isolation of
dehydration-inducible genes encoding
aldehyde dehydrogenases (ALDHs) was reported from the desiccation-tolerant plant Craterostigma plantagineum and Arabidopsis thaliana. ALDHs belong to a family of
NAD(P)+-dependent
enzymes with a broad substrate specificity that catalyze the oxidation of various toxic
aldehydes to
carboxylic acids. Analysis of transcript accumulation revealed that Ath-ALDH3 is induced in response to NaCl,
heavy metals (Cu2+ and Cd2+), and chemicals that induce oxidative stress (
methyl viologen (MV) and H2O2). To investigate the physiological role and possible involvement of ALDHs in stress protection, we generated transgenic Arabidopsis plants overexpressing Ath-ALDH3. Transgenic lines show improved tolerance when exposed to
dehydration, NaCl,
heavy metals (Cu2+ and Cd2+), MV, and H2O2. Tolerance of transgenic plants is correlated with decreased accumulation of lipid peroxidation-derived reactive
aldehydes (as measured by
malondialdehyde) compared to wild-type plants. Increased activity of Ath-ALDH3 appears to constitute a detoxification mechanism that limits
aldehyde accumulation and oxidative stress, thus revealing a novel pathway of detoxification in plants. We suggest that Ath-ALDH3 could be used to obtain plants with tolerance to diverse environmental stresses.