THE 5'-REGION OF ARABIDOPSIS-THALIANA COR15A HAS CIS-ACTING ELEMENTS THAT CONFER COLD-REGULATED, DROUGHT-REGULATED AND ABA-REGULATED GENE-EXPRESSION

Previous nuclear run-on experiments indicated that the cor15a (cold-re gulated) gene of Ambidopsis thaliana L. (Heyn) has a cold-inducible pr omoter (Hajela et al., Plant Physiol 93: 1246-1252, 1990). The data pr esented here indicate that the 5' region of cos15a between nucleotides -305 and +78 (relative to the start of transcription) contains a cis- acting element(s) that can impart cold-regulated gene expression. Hist ochemical staining experiments indicated that the cor15a promoter is i nactive, or very weakly active, in most of the tissues and organs of p lants grown at normal temperature and that it becomes activated throug hout most of the plant in response to low temperature. Notable excepti ons to this general pattern include constitutive activity of the promo ter in anthers of control grown plants and apparent inactivity of the promoter in the roots and ovaries of cold-treated plants. Histochemica l 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 nor mal growth temperature. Finally, gene fusion experiments indicated tha t the 5' region of cor15a between nucleotides -305 and +78, in additio n to imparting cold-regulated gene expression, can impart ABA- and dro ught-regulated gene expression.