The inositol oxygenase gene family of Arabidopsis is involved in the biosynthesis of nucleotide sugar precursors for cell-wall matrix polysaccharides

The nucleotide sugar UDP-glucuronic acid (UDP-GlcA) is the principal precursor for galacturonic acid, xylose, apiose and arabinose residues of the plant cell-wall polymers. UDP-GlcA can be synthesized by two different functional pathways in Arabidopsis involving either UDP-glucose dehydrogenase or i...

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Bibliographic Details
Published in:Planta 2005-05, Vol.221 (2), p.243-254
Main Authors: Kanter, Ulrike, Usadel, Björn, Guerineau, François, Li, Yong, Pauly, Markus, Tenhaken, Raimund
Format: Article
Language:English
Subjects:
Arabidopsis - enzymology
Arabidopsis - genetics
Biosynthesis
Cell Wall - metabolism
Cell walls
Enzymes
Gene expression
Gene Expression Regulation, Developmental
Gene Expression Regulation, Plant
Genes
Inositol Oxygenase
Inositols
Multigene Family
Mutation
Nucleotides
Oxygenases - genetics
Oxygenases - metabolism
Phylogeny
Plants
Plants, Genetically Modified
Polysaccharides - biosynthesis
Reverse transcriptase polymerase chain reaction
Seedlings
Seedlings - genetics
Sugars
Uridine Diphosphate Glucuronic Acid - biosynthesis
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Summary:The nucleotide sugar UDP-glucuronic acid (UDP-GlcA) is the principal precursor for galacturonic acid, xylose, apiose and arabinose residues of the plant cell-wall polymers. UDP-GlcA can be synthesized by two different functional pathways in Arabidopsis involving either UDP-glucose dehydrogenase or inositol oxygenase as the initial enzyme reaction to channel carbohydrates into a pool of UDP sugars used for cell-wall biosynthesis. The genes for the enzyme myo-inositol oxygenase (MIOX) were analyzed in Arabidopsis. They represent a small gene family containing four members. The transcription of all those members indicates a transient and organ-specific gene expression pattern in growing plant tissues as analyzed by RT-PCR and in promoter::GUS reporter gene lines. Two isoforms (MIOX1, MIOX2) are expressed in almost all tissues of the plant, whereas the expression of MIOX4 and MIOX5 is largely restricted to flowers, particularly maturing pollen. T-DNA insertion lines in MIOX genes were isolated; however, single knock-outs show growth phenotypes similar to the wild type. The monosaccharide composition of the cell wall in these mutants is not significantly changed compared to wild type plants. However, the incorporation of 3H-inositol into wall polymers of seedlings is greatly impaired in the mutant lines ΔMIOX1 and ΔMIOX2, which are the only isoforms that are expressed in seedlings.
ISSN:0032-0935
1432-2048
DOI:10.1007/s00425-004-1441-0