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- Title
EFFECTS OF PHENYLACETIC ACID ON ABAXIAL AND ADAXIAL STOMATAL MOVEMENTS AND ITS INTERACTION WITH ABSCISIC ACID.
- Authors
Pemadasa, M. A.
- Abstract
The effects of varying concentrations of phenylacetic acid (FAA), alone and in combination with abscisic acid (ABA), on abaxial and adaxial stomatal movements were examined on isolated epidermis of <em>Commelina communis</em>. Increasing PAA concentration progressively suppressed abaxial opening, while up to 5 mol m-3 PAA produced remarkably wide adaxial apertures but higher concentrations caused closure; the stomatal K+ changed accordingly. PAA, like the K+ ionophore benzo-18-crown-6, showed strong antagonistic interactions with ABA. The results are interpreted by postulating that FAA, like benzo-18-crown-6, increases the membrane permeability to K+. The normal abaxial permeability allows a net K+ gain required for opening, but the PAA-induced increase in permeability causes a net K+ loss leading to closure, because the efflux down a concentration gradient outweighs the influx coupled with proton extrusion. In contrast, the normal K+ content is much less in adaxial than in abaxial guard cells, clear evidence of an inherent restriction to K+ fluxes; this is attributed to restricted. membrane permeability to K+, which PAA is postulated to alleviate progressively with increasing concentration. Thus, an increase in permeability up to a critical limit favours a net K+ gain and promotes opening, but any further increase leads to a net K+ loss and causes closure, as in abaxial guard cells. This interpretation is substantiated by both the progressive reduction of PAA-induced closure with increasing KCI in the medium and the close similarity of the effects of PAA and benzo-18-crown-6, alone and in antagonism with ABA, on abaxial and adaxial stomata.
- Subjects
PHENYLACETIC acid; ABSCISIC acid; STOMATA; EPIDERMIS; LEAF anatomy; PLANT physiology
- Publication
New Phytologist, 1982, Vol 92, Issue 1, p21
- ISSN
0028-646X
- Publication type
Article
- DOI
10.1111/j.1469-8137.1982.tb03359.x