ABA-regulated Gene Expression Research Articles

The 5'-region of Arabidopsis thaliana cor15a has cis-acting elements that confer cold-, drought- and ABA-regulated gene expression.

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.

Effects of abscisic acid analogues on abscisic acid-induced gene expression in barley aleurone protoplasts: Relationship between structure and function of the abscisic acid molecule

The plant hormone abscisic acid (ABA) mediates gene expression in barley aleurone protoplasts. In order to elucidate the essential functional groups of the ABA molecule, the specificity of a number of ABA analogues for inducing ABA-regulated gene (e.g., RAB, BASI) expression in barley aleurone protoplasts was studied. These analogues have modifications at three different positions of the ABA molecule: (a) the 1′-hydroxyl group (1′-deoxy ABA), (b) the carboxyl group (ABA-methyl ester or ABA-glucose ester), and (c) both the 1′-hydroxyl and 4′-carbonyl groups (α-ionylidene acetic acid). The importance of the different putative functional groups was analyzed. The dose-response analysis of ABA analogues upon the induction gene expression showed the following order: ABA > ABA methyl ester > 1′-deoxy ABA > ABA glucose ester > α-ionylidene acetic acid > α-β-ionone. © 1993 Springer-Verlag New York Inc.

ABA-regulated gene expression: cis-acting sequences and trans-acting factors

ABA-regulated gene expression: cis-acting sequences and trans-acting factors William R. Marcotte, Jr,t Mark J. Guiltinan* and Ralph S. Quatrano Department of Biology, University of North Carolina, CB # 3280, Coker Hall, Chapel Hill, NC 27599-3280, U.S.A. 93 Introduction During plant development, phytohormones influence such diverse processes as seed maturation, germination and fruit ripening. The basis of phytohormone action has been a subject of intense interest to plant physiologists for many years, however, the molecular events involved have not been fully elucidated for any given response. While not all responses to hormones involve alterations in gene expression (e.g. stomata1 closure in response to abscisic acid (AHA), see Hetherington & Quatrano, [ 11 for review), it has been demonstrated that the expression of specific sets of RNA and protein molecules can be correlated with many of the physiological responses of plants to these compounds [2-6]. These sets of products may be unique to one response or there may be overlap in the sets between several responses. The expression of hormone-regulated genes may be regulated at several levels, including transcription [ 7 ] . The transcription machinery interacts with the DNA primarily in the 5’ flanking or promoter region of the gene and the pattern of expression of a single gene or set of genes is determined by these interactions. As such, a fundamental understanding of transcriptional regulation will be an important step in elucidating the molecular basis of phytohormone action. In this paper, we discuss recent findings which identify at least some of the cZS sequences involved in AHA-mediated gene regulation [8-10] and a protein factor which interacts specifically with those sequences [ lo]. With this central point in the AHA signal transduction pathway identified, it should now be possible to follow the response chain in both directions ultimately identifying the initial receptor for ABA, the molecular mechanism(s) involved in gene activation, and the role(s) of the proteins produced in response to this hormone.