Over‐expression of different aldehyde dehydrogenase genes in Arabidopsis thaliana confers tolerance to abiotic stress and protects plants against lipid peroxidation and oxidative stress

Abstract

Aldehyde dehydrogenases (ALDHs) play a major role in the detoxification processes of aldehydes generated in plants when exposed to abiotic stress. In previous studies, we have shown that the Arabidopsis thaliana ALDH3I1 gene is transcriptionally activated by abiotic stress, and over-expression of the ALDH3I1 gene confers stress tolerance in transgenic plants. The A. thaliana genome contains 14 ALDH genes expressed in different sub-cellular compartments and are presumably involved in different reactions. The purpose of this study was to compare the potential of a cytoplasmic and a chloroplastic stress-inducible ALDH in conferring stress tolerance under different conditions. We demonstrated that constitutive or stress-inducible expression of both the chloroplastic ALDH3I1 and the cytoplasmic ALDH7B4 confers tolerance to osmotic and oxidative stress. Stress tolerance in transgenic plants is accompanied by a reduction of H2O2 and malondialdehyde (MDA) derived from cellular lipid peroxidation. Involvement of ALDHs in stress tolerance was corroborated by the analysis of ALDH3I1 and ALDH7B4 T-DNA knockout (KO) mutants. Both mutant lines exhibited higher sensitivity to dehydration and salt than wild-type (WT) plants. The results indicate that ALDH3I1 and ALDH7B4 not only function as aldehyde-detoxifying enzymes, but also as efficient reactive oxygen species (ROS) scavengers and lipid peroxidation-inhibiting enzymes. The potential of ALDHs to interfere with H2O2 was also shown for recombinant bacterial proteins.

Significant improvement of stress tolerance in tobacco plants by overexpressing a stress-responsive aldehyde dehydrogenase gene from maize (Zea mays)

“…Reliable controls include observations in the wild type and YFP alone transgenic plants that argue against other possibilities of the predicted subcellular localizations. To our knowledge, characterized plant ALDHs have been demonstrated to be targeted to diverse compartments including mitochondria (Busch and Fromm 1999;Nakazono et al 2000;Deuschle et al 2001;Liu et al 2001;Skibbe et al 2002), plastid/chloroplast (Kirch et al 2001;Weigel et al 1986;Kotchoni et al 2006), Cytosol (Rumpho et al 1983Nair et al 2004;Kotchoni et al 2006), and peroxisome (Nakamura et al 1997). Although the biochemical function of the aldehyde dehydrogenase characterized here is not yet clear, physiological properties suggest a detoxification function in plastids.…”

“…The levels of lipid peroxidation in plant cells were assayed with the thiobarbituric acid test, which determines the amounts of MDA as end product of lipid peroxidation (Heath and Packer 1968;Loreto and Velikova 2001;Sunkar et al 2003). A recent study also demonstrated that the reduced levels of MDA accumulation were correlated with the elevated stress tolerance in the transgenic overexpressors of several Arabidopsis ALDH genes (Kotchoni et al 2006).…”

“…A comprehensive study suggests three genes (ALDH3I1, 3H1 and ALDH7B4) are differentially activated by dehydration, high salinity and ABA in a tissue-specific manner, while the other two genes (ALDH3F1 and ALDH22A1) are constitutively expressed at a low level (Kirch et al 2005). A more recent investigation demonstrated that constitutive or stress-inducible expression of both the chloroplastic ALDH3I1 and the cytoplasmic ALDH7B4 confers tolerance to osmotic and oxidative stresses (Kotchoni et al 2006). …”

Molecular cloning and differential expression of an aldehyde dehydrogenase gene in rice leaves in response to infection by blast fungus

“…Recent reports suggested that Gm TP55 from G. max and ALDH7B4 from A. thaliana might be involved in the detoxification of reactive aldehyde species generated by oxidative stress-associated lipid peroxidation (Kirch et al 2005;Kotchoni et al 2006;Rodrigues et al 2006).…”

“…On the other hand, the ALDH7B6 gene from the moss T. ruralis is constitutively expressed in response to osmotic stress and ABA (Chen et al 2002). But recent study suggested that the Gm TP55 gene from G. max might be involved in the detoxification of reactive aldehyde species generated by oxidative stress-associated lipid peroxidation (Rodrigues et al 2006) and ALDH7B4 from A. thaliana not only function as aldehyde detoxifying enzymes, but also as efficient reactive oxygen species scavengers and lipid peroxidation-inhibiting enzymes (Kirch et al 2005, Kotchoni et al 2006. However, the exact physiological functions of members of the ALDH7 family remain to be elucidated.…”