Expression and regulation of phytoene desaturase during maize seed development

Persistent Link:
http://hdl.handle.net/10150/282172
Title:
Expression and regulation of phytoene desaturase during maize seed development
Author:
Hable, Whitney Elizabeth, 1967-
Issue Date:
1996
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
An essential component of development is the accumulation of specific metabolites in a temporal and tissue-specific manner. The growth regulator abscisic acid (ABA), which accumulates at a specific time during seed development, is required for seed maturation and prevents the premature developmental switch from dormancy to germination ABA accumulates differently in two tissues of the seed; levels in the embryo are several-fold higher than in the endosperm and the temporal accumulation of ABA is also different between these tissues. To begin to understand how ABA accumulation is regulated during seed development, the regulation of ABA biosynthesis was investigated. The approach taken was to examine the expression of the biosynthetic enzyme, phytoene desaturase (PDS), which catalyzes a regulated step in ABA synthesis in several other organisms (Bramley, 1985, Sandmann et al., 1989, Hugueney et al., 1992 and Giuliano et al., 1993). Unlike ABA accumulation, PDS transcript and protein levels were higher in the endosperm than in the embryo. The spatial difference in PDS levels did correlate with levels of the pathway intermediate, beta-carotene, suggesting that PDS may control the synthesis of ABA precursors while subsequent enzymes may regulate ABA accumulation. The temporal expression of Pds was also unrelated to ABA accumulation. In the endosperm, transcript levels were initially high and declined during desiccation while protein levels remained high throughout development. In the embryo, transcript levels were low and constant while protein levels declined. There are several maize mutants (viviparous mutants) disrupted in ABA biosynthesis, resulting in decreased levels of ABA and premature germination. Analysis of the Pds allele and transcript in the viviparous-5 mutant showed that the gene contains multiple insertions and deletions, giving rise to a larger transcript. In addition, the 55 kDa PDS protein was not detected in the vp5 mutant by immunoblot analysis, indicating that the vp5 phenotype results from a mutation at the PDS locus. To determine whether the wild type protein encoded by the ABA mutant, vp2, or the pathway intermediate, lycopene, regulate PDS, transcript and protein levels were compared in wild type and mutant (vp2 and vp7, respectively) seeds. The levels of PDS were not significantly different in vp2 or vp7 wild type and mutant seeds, suggesting that neither the VP2 protein nor lycopene regulate PDS at the steady-state transcript or protein level.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Biology, Molecular.; Biology, Genetics.; Biology, Plant Physiology.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Genetics
Degree Grantor:
University of Arizona
Advisor:
Oishi, Karen K.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleExpression and regulation of phytoene desaturase during maize seed developmenten_US
dc.creatorHable, Whitney Elizabeth, 1967-en_US
dc.contributor.authorHable, Whitney Elizabeth, 1967-en_US
dc.date.issued1996en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractAn essential component of development is the accumulation of specific metabolites in a temporal and tissue-specific manner. The growth regulator abscisic acid (ABA), which accumulates at a specific time during seed development, is required for seed maturation and prevents the premature developmental switch from dormancy to germination ABA accumulates differently in two tissues of the seed; levels in the embryo are several-fold higher than in the endosperm and the temporal accumulation of ABA is also different between these tissues. To begin to understand how ABA accumulation is regulated during seed development, the regulation of ABA biosynthesis was investigated. The approach taken was to examine the expression of the biosynthetic enzyme, phytoene desaturase (PDS), which catalyzes a regulated step in ABA synthesis in several other organisms (Bramley, 1985, Sandmann et al., 1989, Hugueney et al., 1992 and Giuliano et al., 1993). Unlike ABA accumulation, PDS transcript and protein levels were higher in the endosperm than in the embryo. The spatial difference in PDS levels did correlate with levels of the pathway intermediate, beta-carotene, suggesting that PDS may control the synthesis of ABA precursors while subsequent enzymes may regulate ABA accumulation. The temporal expression of Pds was also unrelated to ABA accumulation. In the endosperm, transcript levels were initially high and declined during desiccation while protein levels remained high throughout development. In the embryo, transcript levels were low and constant while protein levels declined. There are several maize mutants (viviparous mutants) disrupted in ABA biosynthesis, resulting in decreased levels of ABA and premature germination. Analysis of the Pds allele and transcript in the viviparous-5 mutant showed that the gene contains multiple insertions and deletions, giving rise to a larger transcript. In addition, the 55 kDa PDS protein was not detected in the vp5 mutant by immunoblot analysis, indicating that the vp5 phenotype results from a mutation at the PDS locus. To determine whether the wild type protein encoded by the ABA mutant, vp2, or the pathway intermediate, lycopene, regulate PDS, transcript and protein levels were compared in wild type and mutant (vp2 and vp7, respectively) seeds. The levels of PDS were not significantly different in vp2 or vp7 wild type and mutant seeds, suggesting that neither the VP2 protein nor lycopene regulate PDS at the steady-state transcript or protein level.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectBiology, Molecular.en_US
dc.subjectBiology, Genetics.en_US
dc.subjectBiology, Plant Physiology.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineGeneticsen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorOishi, Karen K.en_US
dc.identifier.proquest9713407en_US
dc.identifier.bibrecord.b34402020en_US
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