Previous nuclear run-on experiments indicated that the cor15a (cold-regulated) gene of Arabidopsis thaliana L. (Heyn) has a cold-inducible promoter (Hajela et al., Plant Physiol 93: 1246-1252, 1990). The data presented here indicate that the 5' region of cor15a between nucleotides -305 and +78 (relative to the start of transcription) contains a cis-acting element(s) that can impart cold-regulated gene expression. Histochemical staining experiments indicated that the cor15a promoter is inactive, or very weakly active, in most of the tissues and organs of plants grown at normal temperature and that it becomes activated throughout most of the plant in response to low temperature. Notable exceptions to this general pattern include constitutive activity of the promoter in anthers of control grown plants and apparent inactivity of the promoter in the roots and ovaries of cold-treated plants. Histochemical staining experiments also indicated that low temperature regulation of cor15a does not involve the synthesis of a regulatory molecule that can spread throughout the plant and induce cor gene expression at normal growth temperature. Finally, gene fusion experiments indicated that the 5' region of cor15a between nucleotides -305 and +78, in addition to imparting cold-regulated gene expression, can impart ABA- and drought-regulated gene expression.