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Sucrose rescues seedling establishment but not germination of Arabidopsis mutants disrupted in peroxisomal fatty acid catabolism

Pinfield-Wells, H., Rylott, E.L., Gilday, A.D., Graham, S., Job, K., Larson, T.R. and Graham, I.A. (2005) Sucrose rescues seedling establishment but not germination of Arabidopsis mutants disrupted in peroxisomal fatty acid catabolism. The Plant Journal, 43 (6). pp. 861-872. ISSN 0960-7412

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Abstract

The Arabidopsis acyl-CoA oxidase (ACX) family comprises isozymes with distinct fatty acid chain-length specificities that together catalyse the first step of peroxisomal fatty acid β-oxidation. We have isolated and characterized T-DNA insertion mutants in the medium to long-chain (ACX1) and long-chain (ACX2) acyl-CoA oxidases, and show that the corresponding endogenous activities are decreased in the mutants. Lipid catabolism during germination and early post-germinative growth was unaltered in the acx1-1 mutant, but slightly delayed in the acx2-1 mutant, with 3-day-old acx2-1 seedlings accumulating long-chain acyl-CoAs. In acx1-1 and acx2-1, seedling growth and establishment in the absence of an exogenous supply of sucrose was unaffected. Seedlings of the double mutant acx1-1 acx2-1 were unable to catabolize seed storage lipid, and accumulated long-chain acyl-CoAs. The acx1-1 acx2-1 seedlings were also unable to establish photosynthetic competency in the absence of an exogenous carbon supply, a phenotype that is shared with a number of other Arabidopsis mutants disrupted in storage lipid breakdown. Germination frequency of the double mutant was significantly reduced compared with wild-type seeds. This was unaffected by the addition of exogenous sucrose, but was improved by dormancy-breaking treatments such as cold stratification and after-ripening. We show that the acx1-1, acx2-1 and acx1-2 acx2-1 double mutants and the ketoacyl-CoA thiolase-2 (kat2) mutant exhibit a sucrose-independent germination phenotype comparable with that reported for comatose (cts-2), a mutant in a peroxisomal ABC transporter which exhibits enhanced dormancy. This demonstrates an additional role beyond that of carbon provision for the β-oxidation pathway during germination or in dormant seeds.

Item Type: Article
Copyright, Publisher and Additional Information: Open access copy available from the journal web site.
Keywords: long-chain acyl-CoA oxidase, germination, beta-oxidation, Arabidopsis, oilseeds, lipid mobilization
Institution: The University of York
Academic Units: The University of York > Biology (York)
Depositing User: Open Access From Journal
Date Deposited: 23 Dec 2008 11:28
Last Modified: 23 Dec 2008 11:28
Published Version: http://dx.doi.org/10.1111/j.1365-313X.2005.02498.x
Status: Published
Publisher: Wiley-Blackwell
Refereed: Yes
Identification Number: 10.1111/j.1365-313X.2005.02498.x
URI: http://eprints.whiterose.ac.uk/id/eprint/5074

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