Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/197853
Type: Artigo de periódico
Title: Sugar Levels Modulate Sorbitol Dehydrogenase Expression In Maize.
Author: de Sousa, Sylvia Morais
Paniago, Mário del Giúdice
Arruda, Paulo
Yunes, José Andrés
Abstract: The first step in sucrose use by maize kernels produces fructose, regardless of whether the initial reaction is catalyzed by an invertase or the reversible sucrose synthase. This fructose can enter subsequent metabolism via hexokinase, or in maize kernels, by a sorbitol dehydrogenase that reversibly converts fructose + NADH to sorbitol + NAD. High levels of SDH activity suggest that kernels synthesize considerable amounts of sorbitol, but the molecular mechanism and functional role for this process have remained equivocal. To gain insights on the role of sorbitol synthesis in maize endosperm we cloned and characterized the transcriptional control of the maize sorbitol dehydrogenase (Sdh1) gene. Data indicated that Sdh1 was essentially kernel- and endosperm-specific, with maximal expression at both the mRNA and enzyme activity levels during early kernel development. Expression was elevated in high-sugar mutants (sugary1, shrunken2), also by sugar injections, and was more pronounced when transfected tissues were incubated at low oxygen concentrations. Control of Sdh1 expression in our transient assays was largely dependent on the first intron of Sdh1. We speculate that SDH activity may represent an adaptation to the high-sugar/low-oxygen environment of the endosperm. Under these conditions, the NADH-dependent reduction of fructose to sorbitol would regenerate NAD[+], thus contributing to the maintenance of the redox and energy status of the cell.
Subject: Gene Expression Regulation, Enzymologic
Gene Expression Regulation, Plant
Genome, Plant
L-iditol 2-dehydrogenase
Molecular Sequence Data
Rna, Messenger
Regulatory Sequences, Nucleic Acid
Sorbitol
Sucrose
Transcription, Genetic
Zea Mays
Rights: fechado
Identifier DOI: 10.1007/s11103-008-9362-0
Address: http://www.ncbi.nlm.nih.gov/pubmed/18566893
Date Issue: 2008
Appears in Collections:Unicamp - Artigos e Outros Documentos

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