Journal Article

On the role of abscisic acid in seed dormancy of red rice

Alberto Gianinetti and Paolo Vernieri

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 58, issue 12, pages 3449-3462
Published in print September 2007 | ISSN: 0022-0957
Published online September 2007 | e-ISSN: 1460-2431 | DOI:
On the role of abscisic acid in seed dormancy of red rice

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Abscisic acid (ABA) is commonly assumed to be the primary effector of seed dormancy, but conclusive evidence for this role is lacking. This paper reports on the relationships occurring in red rice between ABA and seed dormancy. Content of free ABA in dry and imbibed caryopses, both dormant and after-ripened, the effects of inhibitors, and the ability of applied ABA to revert dormancy breakage were considered. The results indicate: (i) no direct correlation of ABA content with the dormancy status of the seed, either dry or imbibed; (ii) different sensitivity to ABA of non-dormant seed and seed that was forced to germinate by fluridone; and (iii) an inability of exogenous ABA to reinstate dormancy in fluridone-treated seed, even though applied at a pH which favoured high ABA accumulation. These considerations suggest that ABA is involved in regulating the first steps of germination, but unidentified developmental effectors that are specific to dormancy appear to stimulate ABA synthesis and to enforce the responsiveness to this phytohormone. These primary effectors appear physiologically to modulate dormancy and via ABA they effect the growth of the embryo. Therefore, it is suggested that ABA plays a key role in integrating the dormancy-specific developmental signals with the control of growth.

Keywords: Abscisic acid; development arrest; Oryza sativa f. spontanea; pericarp splitting; red rice; seed dormancy; seedling growth

Journal Article.  9086 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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