Abscisic acid mechanism

Such questions have been raised for the catabolic products of auxins, abscisic acid, conjugates of auxins, and gibberellin, and for the hormonal role of cytokinins and auxins in tRNA molecules, but are not reviewed in this article (17). A satisfactory answer to this question requires elucidation of the cellular mechanisms (discussed in this paper) that are believed to be primarily under hormonal regulation. 

Y. Todoroki N. Hirai, Abscisic Analogs for Probing the Mechanism of Abscisic Acid Reception and Inactivation. In Studies in Natural Product Chemistry Ed. Atta-ur-Rahman, Ed. Elsevier Amsterdam, 2002 Vol. 27, pp 321-360. 

The mechanism of action of abscisic acid (ABA) has been studied to the greatest extent in the barley aleurone system (29), in which ABA counteracts the effect of GA in the induction of hydrolases. This action of ABA has largely been the basis for speculating that ABA may act specifically to inhibit, by some unknown mechanism, DNA-dependent RNA synthesis. Much evidence indicates that ABA acts at the transcriptional level, but it also has been proposed that the inhibition of induction of a-amylase synthesis is caused, at least in part, by an effect on translation because ABA still inhibited the formation of a-amylase at 12 hr when cordycepin (an inhibitor of RNA synthesis) no longer had an effect (30). 

Figure 4. Proposed model of molecular interactions in the herbicidal mechanism of action of auxin herbicides in sensitive dicot and grass weeds. ABA, abscisic acid ACC, 1-aminocyclopropane-1-carboxylic acid ROS, reactive oxygen species. Modified from [7].

Abscisic acid analogs for probing the mechanism of abscisic acid reception and inactivation... 

ABSCISIC ACID ANALOGS FOR PROBING THE MECHANISM OF ABSCISIC ACID RECEPTION AND... 

ABSTRACT More than 100 abscisic acid (ABA) analogs have been reported so far. Some were synthesized to clarify structure-activity relationships, and others were developed as tools for investigating the molecular mechanism of ABA action. These analogs, especially those that can be useful tools for studying ABA reception and catabolic inactivation, are summarized together with their design concepts, structural properties and bioactivities. 

Abscisic-acid-deficient tomato and potato plants do not respond to mechanical wounding by accumulation of pin 2 mRNA, therefore providing evidence that ABA is involved in wound response. It was demonstrated that the site of action of jasmonic acid is located downstream to the site of action of ABA. The fact that tomato leaves of ABA-deficient plants showed increased levels of jasmonic acid, similar to those found in wild-type plants after treatment with 18 3, supports a hypothesis that during tissue injury ABA might lead to the activation of jasmonic acid synthesis through activation of a fatty-acid-releasing enzyme such as lipase [186]. 

Hiraki Y, Ota Y (1975) Relationship between growth-inhibition and ethylene production by mechanical stimulation in Lilium longiflorum. Plant Cell Physiol 16 185-189 Hiron RWP, Wright STC (1973) The role of endogenous abscisic acid in the response of plants to stress. J Exp Bot 24 769-781... 

Ingersoll RB, Smith OE (1971) Transport of abscisic acid. Plant Cell Physiol 12 301-309 Itai C, Ben-Zioni A (1974) Regulation of plant responses to high temperature. In Bieleski RL, Ferguson AR, Cresswell MM (eds) Mechanism of regulation of plant growth. Roy Soc N Z Wellington, pp 477-482... 

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