Regulation of ascorbate biosynthesis in green algae has evolved to enable rapid stress‐induced response via theVTC2gene encoding GDP‐l ‐galactose phosphorylase
| Autor: | Ralph Bock, Szilvia Z. Tóth, Valéria Nagy, André Vidal-Meireles, Laise Rosado-Souza, Laura Zsigmond, Juliane Neupert, Anikó Galambos, Alisdair R. Fernie, László Kovács |
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| Rok vydání: | 2017 |
| Předmět: |
0106 biological sciences
0301 basic medicine Light Physiology Chlamydomonas reinhardtii Ascorbic Acid Plant Science Photosynthesis 01 natural sciences Electron Transport 03 medical and health sciences Glycogen phosphorylase chemistry.chemical_compound Biosynthesis Gene Expression Regulation Plant Stress Physiological Metabolomics RNA Messenger Gene Regulation of gene expression Vitamin C biology Chlamydomonas Hydrogen Peroxide biology.organism_classification Phosphoric Monoester Hydrolases Circadian Rhythm MicroRNAs 030104 developmental biology Biochemistry chemistry 010606 plant biology & botany |
| Zdroj: | New Phytologist |
| ISSN: | 1469-8137 0028-646X |
| DOI: | 10.1111/nph.14425 |
| Popis: | Ascorbate (vitamin C) plays essential roles in stress resistance, development, signaling, hormone biosynthesis and regulation of gene expression; however, little is known about its biosynthesis in algae. In order to provide experimental proof for the operation of the Smirnoff-Wheeler pathway described for higher plants and to gain more information on the regulation of ascorbate biosynthesis in Chlamydomonas reinhardtii, we targeted the VTC2 gene encoding GDP-l-galactose phosphorylase using artificial microRNAs. Ascorbate concentrations in VTC2 amiRNA lines were reduced to 10% showing that GDP-l-galactose phosphorylase plays a pivotal role in ascorbate biosynthesis. The VTC2 amiRNA lines also grow more slowly, have lower chlorophyll content, and are more susceptible to stress than the control strains. We also demonstrate that: expression of the VTC2 gene is rapidly induced by H2 O2 and 1 O2 resulting in a manifold increase in ascorbate content; in contrast to plants, there is no circadian regulation of ascorbate biosynthesis; photosynthesis is not required per se for ascorbate biosynthesis; and Chlamydomonas VTC2 lacks negative feedback regulation by ascorbate in the physiological concentration range. Our work demonstrates that ascorbate biosynthesis is also highly regulated in Chlamydomonas albeit via mechanisms distinct from those previously described in land plants. |
| Databáze: | OpenAIRE |
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