Sequence was obtained from a cDNA clone, designated ERD1, isolated from a cDNA library of 1-hour-dehydrated plants of Arabidopsis thaliana L. The clone (3150 bp) contains an open reading frame of 946 amino acid residues with greater than 34% sequence identity to the regulatory subunit of the Clp ATP-dependent protease in Escherichia coli and contains a putative chloroplast-targeting signal at the N-terminus. Southern blot analysis suggested the presence of additional ERD1-related genes in A. thaliana. The expression of ERD1 gene was strongly induced by dehydration-stress but not by heat-, cold-, or heavy-metal-stress. In addition ERD1 gene-expression was not strongly affected by treatment with plant growth regulators, such as auxin, cytokinin, abscisic acid, and gibberellic acid, or by starvation-stress for 10 hours.