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Journal of Amino Acids
Volume 2012 (2012), Article ID 493209, 9 pages
http://dx.doi.org/10.1155/2012/493209
Research Article

Polyamine-Induced Rapid Root Abscission in Azolla pinnata

1Faculty of Science, University of the Ryukyus, Nishihara 903-0213, Japan
2Department of Biology, Sonoma State University, Rohnert Park, CA 94928, USA
3Department of Chemistry, Sonoma State University, Rohnert Park, CA 94928, USA

Received 1 June 2012; Accepted 3 August 2012

Academic Editor: Maria Patricia Benavides

Copyright © 2012 Sushma Gurung et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Floating ferns of the genus Azolla detach their roots under stress conditions, a unique adaptive response termed rapid root abscission. We found that Azolla pinnata plants exhibited dose-dependent rapid root abscission in response to the polyamines spermidine and spermine after a substantial time lag (>20 min). The duration of the time lag decreased in response to high pH and high temperature whereas high light intensity increased the time lag and markedly lowered the rate of abscission. The oxidation products of polyamines, 1,3-diaminopropane, β-alanine and hydrogen peroxide all failed to initiate root abscission, and hydroxyethyl hydrazine, an inhibitor of polyamine oxidase, did not inhibit spermine-induced root abscission. Exposure of A. pinnata to the polyamines did not result in detectable release of NO and did not affect nitrite-dependent NO production. The finding of polyamine-induced rapid root abscission provides a facile assay for further study of the mode of action of polyamines in plant stress responses.