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Germination and storage reserve mobilization are regulated independently in Arabidopsis

Pritchard, S.L., Charlton, W.L., Baker, A. and Graham, I.A. (2002) Germination and storage reserve mobilization are regulated independently in Arabidopsis. The Plant Journal, 31 (5). pp. 639-647. ISSN 0960-7412

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Abstract

The phytohormone abscisic acid (ABA) inhibits the germination of many seeds, including Arabidopsis, but the mechanism for this is not known. In cereals, ABA inhibits the expression of genes involved in storage reserve mobilization. We have found that in Arabidopsis ABA decreases transcription from the promoters of marker genes for β-oxidation and the glyoxylate cycle, essential pathways for the conversion of storage lipid (triacylglycerol) into sucrose. Thirty per cent of stored lipid is broken down over 6 days following imbibition of ABA-treated seed. Sucrose levels in ABA-treated seeds, rather than decreasing as under normal growth conditions, actually double during the 3 days following imbibition. This sucrose is derived from triacylglycerol as demonstrated by two mutants disrupted in the conversion of triacylglycerol into sucrose, kat2 and icl1, which do not accumulate sucrose in the presence of ABA. We conclude that the ABA block on germination is not a consequence of inhibition of storage lipid mobilization. Two independent programmes appear to operate, one that is blocked by ABA, governing developmental growth resulting in germination; and a second that governs storage lipid mobilization which is largely ABA-independent.

Item Type: Article
Copyright, Publisher and Additional Information: Open access copy available from the journal web site.
Keywords: ABA, triacylglycerol, sucrose, beta-oxidation, glyoxylate cycle
Academic Units: The University of Leeds > Faculty of Biological Sciences (Leeds) > Institute of Integrative and Comparative Biology (Leeds)
The University of York > Biology (York)
The University of Leeds > Faculty of Biological Sciences (Leeds) > Institute of Molecular and Cellular Biology (Leeds)
Depositing User: Open Access From Journal
Date Deposited: 22 Dec 2008 17:52
Last Modified: 29 Sep 2010 14:22
Published Version: http://dx.doi.org/10.1046/j.1365-313X.2002.01376.x
Status: Published
Publisher: Wiley-Blackwell
Refereed: Yes
Identification Number: 10.1046/j.1365-313X.2002.01376.x
URI: http://eprints.whiterose.ac.uk/id/eprint/5100

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