Identification of Solanum tuberosum genes responsive to culture filtrates (CF) from Erwinia carotovora subsp. carotovora led to the isolation of a full-length cDNA with high sequence similarity to several alcohol dehydrogenases. Accumulation of transcripts corresponding to this defence-related alcohol dehydrogenase (drd-1) was rapidly induced in CF-treated and wounded plants. The gene was also responsive to molecules involved in defence signalling such as salicylic acid, methyl jasmonate and ethylene. To elucidate the biochemical function of DRD-1, its cDNA was expressed in Escherichia coli. Enzymatic assays revealed that DRD-1 is an alcohol:NADP+ oxidoreductase with preference for various aromatic and aliphatic aldehydes. The enzyme exhibited high activity with several aldehydes including 2-methoxybenzaldehyde, 3-methoxybenzaldehyde, salicylaldehyde, o-vanillin, cinnamaldehyde, hydrocinnamaldehyde, hexanal and octanal. Identification of the reaction product by thin-layer chromatography confirmed the reduction of aldehydes to alcohols. Enzymatic activity measured with 2-methoxybenzaldehyde as a substrate was increased in salicylic acid- or methyl jasmonate-treated plants. These data suggest that DRD-1 may play an important role in potato defence response to Erwinia carotovora.