Stress-associated aldehyde dehydrogenases in Arabidopsis thaliana: Redox control, biochemical requirements and interacting pathways

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Aldehyde dehydrogenases (ALDHs) not only function as aldehyde-detoxifying enzymes but also as reactive oxygen species scavengers and lipid peroxidation inhibiting proteins. In the previous research programmes a genetic platform was developed for Arabidopsis ALDH genes with a potential role in osmotic stress adaptation and novel ALDHs. This proposal builds upon the previously developed tools with the aim to position the ALDHs in the physiological, cellular and biochemical context. Recent results indicate that the function of these enzymes may be regulated by their redox state. Here we will characterize the biochemical and regulatory pathways of stress-associated ALDHs and analyze their linkage to other processes in A. thaliana. The following experimental approaches will be pursued: 1.) ALDH promoter-GUS lines will be used in a forward genetic screen to identify regulators that affect ALDH expression; 2.) Functional interaction of ALDHs with partners from other stress-associated pathways will be studied in a combinatorial proteomics approach. Using site-specific mutagenesis, affinity-purified mutated ALDH proteins will be utilized to identify residues important for protein function and oxidative protection; 3.) Interacting partners will be identified by co-immunoprecipitation assays and affinity chromatography with immobilized ALDHs.