Isolation, expression and functional analysis of acDNA encoding phytoene desaturase, a carotenoid biosynthetic enzyme from rice, Oryza sativa L.
Item
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Title
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Isolation, expression and functional analysis of acDNA encoding phytoene desaturase, a carotenoid biosynthetic enzyme from rice, Oryza sativa L.
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Identifier
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AAI9830780
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identifier
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9830780
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Creator
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Yoganathan, Arulmolee.
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Contributor
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Adviser: Eleanore T. Wurtzel
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Date
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1998
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Molecular | Biology, Botany | Biology, Plant Physiology
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Abstract
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The mechanisms that underlie the lack of carotenoid accumulation in rice endosperm were investigated, en route to engineering carotenoid biosynthesis in rice. The genetic capacity to synthesize and accumulate carotenoids in photosynthetic tissues and not in endosperm of rice implies a tissue specific regulation. One of the possible causes of the absence of colored carotenoid accumulation in rice endosperm may be the lack of expression of one or more carotenoid biosynthetic genes. Furthermore, the presence of more than one gene involved in the tissue specific expression of carotenoid biosynthetic enzymes is a possibility too. To investigate the tissue specific regulation, the expression of the first two carotenoid biosynthetic genes, Psy (phytoene synthase) and Pds (phytoene desaturase), in rice was studied.;Results clearly shows that the carotenoid biosynthetic enzymes PSY and PDS were encoded by single copy genes mapped to chromosome # 12 and # 3, respectively. Both Psy and Pds were expressed not only in leaf but also in endosperm. Psy was constitutively expressed during endosperm development, whereas Pds showed a temporal regulation at the transcriptional level. The 2027 bp rice Pds cDNA isolated shared 80% and 89% identities with maize Pds, at the nucleotide and amino acid sequence levels, respectively. The open reading frame of 566 amino acid residues with predicted molecular weight of 63.5 kDa contained a 10.3 kDa putative transit peptide region consisting of 92 amino acid residues and a dinucleotide binding domain necessary for the enzyme activity. The predicted amino acid sequence of the mature rice PDS shared 96% identity with maize PDS. When complemented with Erwinia uredovora genes encoding GGPPS and PSY (for the synthesis of phytoene), the protein encoded by the rice Pds catalyzed a two step desaturation of phytoene resulting in the synthesis of {dollar}\zeta{dollar}-carotene.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
