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Seed dormancy and ABA metabolism in Arabidopsis and barley: the role of ABA 8'-hydroxylase

Millar, Anthony; Jacobsen, J; Ross, John J; Helliwell, Christopher Andrew; Poole, Andrew; Scofield, Graham; Reid, James B; Gubler, Frank

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We have investigated the relationship between seed dormancy and abscisic acid (ABA) metabolism in the monocot barley and the dicot Arabidopsis. Whether dormant (D) or non-dormant (ND), dry seed of Arabidopsis and embryos of dry barley grains all had similarly high levels of ABA. ABA levels decreased rapidly upon imbibition, although they fell further in ND than in D. Gene expression profiles were determined in Arabidopsis for key ABA biosynthetic [the 9-cis epoxycarotenoid dioxygenaseq3gene...[Show more]

dc.contributor.authorMillar, Anthony
dc.contributor.authorJacobsen, J
dc.contributor.authorRoss, John J
dc.contributor.authorHelliwell, Christopher Andrew
dc.contributor.authorPoole, Andrew
dc.contributor.authorScofield, Graham
dc.contributor.authorReid, James B
dc.contributor.authorGubler, Frank
dc.date.accessioned2015-12-08T22:14:11Z
dc.identifier.issn0960-7412
dc.identifier.urihttp://hdl.handle.net/1885/30124
dc.description.abstractWe have investigated the relationship between seed dormancy and abscisic acid (ABA) metabolism in the monocot barley and the dicot Arabidopsis. Whether dormant (D) or non-dormant (ND), dry seed of Arabidopsis and embryos of dry barley grains all had similarly high levels of ABA. ABA levels decreased rapidly upon imbibition, although they fell further in ND than in D. Gene expression profiles were determined in Arabidopsis for key ABA biosynthetic [the 9-cis epoxycarotenoid dioxygenaseq3gene family] and ABA catabolic [the ABA 8′-hydroxylase gene family (CYP707A)] genes. Of these, only the AtCYP707A2 gene was differentially expressed between D and ND seeds, being expressed to a much higher level in ND seeds. Similarly, a barley CYP707 homologue, (HvABA8′OH-1) was expressed to a much higher level in embryos from ND grains than from D grains. Consistent with this, in situ hybridization studies showed HvABA8′OH-1 mRNA expression was stronger in embryos from ND grains. Surprisingly, the signal was confined in the coleorhiza, suggesting that this tissue plays a key role in dormancy release. Constitutive expression of a CYP707A gene in transgenic Arabidopsis resulted in decreased ABA content in mature dry seeds and a much shorter after-ripening period to overcome dormancy. Conversely, mutating the CYP707A2 gene resulted in seeds that required longer after-ripening to break dormancy. Our results point to a pivotal role for the ABA 8′-hydroxylase gene in controlling dormancy and that the action of this enzyme may be confined to a particular organ as in the coleorhiza of cereals.
dc.publisherBlackwell Publishing Ltd
dc.sourceThe Plant Journal
dc.subjectKeywords: Enzyme kinetics; Seed; Tissue; Abscisic acid (ABA); Coleorhiza; Dicot Arabidopsis; Crops; 9 cis epoxy carotenoid dioxygenase; 9-cis-epoxy-carotenoid dioxygenase; abscisic acid; abscisic acid 8' hydroxylase; abscisic acid 8'-hydroxylase; bacterial DNA; cyt Abscisic acid; Abscisic acid 8'hydroxylase; Arabidopsis; Barley; Coleorhiza; Dormancy
dc.titleSeed dormancy and ABA metabolism in Arabidopsis and barley: the role of ABA 8'-hydroxylase
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume45
dc.date.issued2006
local.identifier.absfor060705 - Plant Physiology
local.identifier.ariespublicationu4325460xPUB71
local.type.statusPublished Version
local.contributor.affiliationMillar, Anthony, College of Medicine, Biology and Environment, ANU
local.contributor.affiliationJacobsen, J, CSIRO Plant Industry
local.contributor.affiliationRoss, John J, University of Tasmania
local.contributor.affiliationHelliwell, Christopher Andrew , CSIRO
local.contributor.affiliationPoole, Andrew, CSIRO
local.contributor.affiliationScofield, Graham, CSIRO
local.contributor.affiliationReid, James B, University of Tasmania
local.contributor.affiliationGubler, Frank , CSIRO
local.description.embargo2037-12-31
local.bibliographicCitation.startpage942
local.bibliographicCitation.lastpage954
local.identifier.doi10.1111/j.1365-313X.2006.02659.x
dc.date.updated2015-12-08T07:48:29Z
local.identifier.scopusID2-s2.0-33644763935
CollectionsANU Research Publications

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