Myoinositol oxygenase controls the level of myoinositol in Arabidopsis, but does not increase ascorbic acid
| Autor: | Raimund Tenhaken, Stefanie Endres |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
Oxygenase
Antioxidant Light Transcription Genetic Physiology medicine.medical_treatment Metabolite Arabidopsis Plant Science Ascorbic Acid Biology Polymerase Chain Reaction Inositol oxygenase chemistry.chemical_compound Biosynthesis Genetics medicine Inositol Chromatography High Pressure Liquid DNA Primers Arabidopsis Proteins Inositol Oxygenase Darkness Ascorbic acid Plant Leaves Metabolic pathway Biochemistry chemistry Research Article |
| Zdroj: | Plant physiology. 149(2) |
| ISSN: | 0032-0889 |
| Popis: | Ascorbic acid (AsA) is a major plant antioxidant. Mutants like vtc1 show a reduced AsA concentration, which confirmed by genetic evidence the previously proposed AsA pathway via GDP-Man. Here we investigate the role of an animal-like alternative biosynthesis route to AsA, starting from the metabolite d-GlcUA, which is produced in plants by myoinositol oxygenase (Miox). Miox-overexpressing lines have a more than 30-fold up-regulated transcript level and higher enzymatic activity as shown by increased incorporation of Miox-derived sugars into cell wall polymers. In addition, Miox overexpressors exhibit a lower steady-state level of myoinositol and accumulate less myoinositol in feeding experiments due to an enhanced turnover rate. The AsA concentration remains the same in wild-type and Miox overexpressor lines. Even challenging plants with stress, which increases AsA concentration 4-fold, reveals no difference in AsA biosynthesis between wild-type and Miox-overexpressing lines. We conclude that d-GlcUA derived from the Miox reaction plays a negligible role for AsA biosynthesis. However, Miox controls the metabolite level of myoinositol in plants. |
| Databáze: | OpenAIRE |
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