Mechanisms of action of abscisic acid at the cellular level

Abstract

summary Abscisic acid (ABA) has been implicated in the control of a diverse range of physiological processes in higher plants. In this review, we focus on the events which constitute the cellular responses to ABA. Current evidence suggests that it is possible to classify the responses to ABA on the basis of whether they are rapid, involving ion fluxes (typified by the stomatal response), or slower and requiring alterations to gene expression (for example the response of cereal embryos to ABA). In our consideration of ABA stimulus response coupling pathways, we have chosen to highlight the role of the calcium ion in the rapid responses, while we have concentrated on the contribution of as‐acting elements and trans‐acting factors in the regulation of ABA‐responsive genes. We also draw attention to the possibility that interaction may exist between these pathways. Additionally, we discuss the controls of ABA concentrations during development and in response to environmental stimuli. Factors which contribute to the controls of ABA sensitivity are also reviewed. In our conclusions, we suggest that a general role for ABA may be to prepare tissue for entry into a new and different physiological state, perhaps by resetting the direction of cellular metabolism.

Promoter and expression studies on an Arabidopsis thaliana dehydrin gene

“…The phytohormone abscisic acid (ABA) is implicated in the control of processes resulting in tolerance [1,3 5]. Endogenous ABA concentrations increase in plants in response to stress [6] and many, but not all stress-induced genes, are responsive to exogenous ABA treatment [1,[3][4][5]. Many genes that respond to ABA are also expressed during seed development during the late stages of embryogenesis and are thought to be involved in the development of desiccation tolerance [1].…”

Abscisic acid in lichens: variation, water relations and metabolism

“…There are cytosolic responses by osmoregulation as well as nuclear responses by regulation of gene expression (Zeevaart & Creelman, 1988 ;Hetherington & Quatrano, 1991). An induction or enhancement of desiccation tolerance by ABA was shown for liverworts, (Hellwege et al, 1992(Hellwege et al, , 1994.…”

Differential Interactions of Promoter Elements in Stress Responses of the Arabidopsis Adh Gene

“…Both dehydration and cold stress have been correlated with increased levels of ABA in plant tissues (Guy, 1990;Hetherington and Quatrano, 1991;Jackson, 1991), but the correlation with anaerobic stress is less clear. The Arabidopsis Adh promoter contains the G-box-1 sequence (see introduction and Fig.…”

“…Cold stress has been associated with increased levels of the phytohormone ABA in plants (Guy, 1990;Hetherington and Quatrano, 1991;Jackson, 1991), but there is no direct evidente that hypoxic stress is correlated with ABA content in plant tissue. Maize plantlets pretreated with ABA were shown to be better able to withstand hypoxic stress, iind this increased tolerance was correlated with an increase of ADH activity, but ABA has not been shown to induce maize ADH activity directly (Hwang and VanToai, 1991 These data pose the question whether induction by low temperature and ABA use the same signal-transduction pathway and involve the same cis-acting regulatory sequences.…”

“…The suggestion that cold response is related to ABA levels led us to investigate whether other environmental stresses that are correlated with ABA levels, such as dehydration stress (Guy, 1990;Hetherington and Quatrano, 1991;Jackson, 1991), also induce the Arubidopsis Adh promoter. We found that the gene is strongly induced when plants are dehydrated in a 0.6 M mannitol solution (Fig.…”