Arabidopsis thaliana ASN2encoding asparagine synthetase is involved in the control of nitrogen assimilation and export during vegetative growth
| Autor: | Fabienne Soulay, Olivier Grandjean, Michèle Reisdorf-Cren, Jean-Christophe Avice, Marianne Azzopardi, Akira Suzuki, Céline Masclaux-Daubresse, Laure Gaufichon, Toshiharu Hase, Stéphanie Boutet-Mercey, Anne Marmagne, Yukiko Sakakibara, Gilles Clément, Guillaume Tcherkez |
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| Rok vydání: | 2012 |
| Předmět: |
0106 biological sciences
Alanine 0303 health sciences Physiology Nitrogen assimilation fungi Asparagine synthetase food and beverages Plant Science Biology 01 natural sciences 03 medical and health sciences chemistry.chemical_compound Biochemistry chemistry Ammonium Asparagine Phloem Cellular localization 030304 developmental biology 010606 plant biology & botany Aspartate—ammonia ligase |
| Zdroj: | Plant, Cell & Environment. 36:328-342 |
| ISSN: | 0140-7791 |
| DOI: | 10.1111/j.1365-3040.2012.02576.x |
| Popis: | We investigated the function of ASN2, one of the three genes encoding asparagine synthetase (EC 6.3.5.4), which is the most highly expressed in vegetative leaves of Arabidopsis thaliana. Expression of ASN2 and parallel higher asparagine content in darkness suggest that leaf metabolism involves ASN2 for asparagine synthesis. In asn2-1 knockout and asn2-2 knockdown lines, ASN2 disruption caused a defective growth phenotype and ammonium accumulation. The asn2 mutant leaves displayed a depleted asparagine and an accumulation of alanine, GABA, pyruvate and fumarate, indicating an alanine formation from pyruvate through the GABA shunt to consume excess ammonium in the absence of asparagine synthesis. By contrast, asparagine did not contribute to photorespiratory nitrogen recycle as photosynthetic net CO(2) assimilation was not significantly different between lines under both 21 and 2% O(2). ASN2 was found in phloem companion cells by in situ hybridization and immunolocalization. Moreover, lack of asparagine in asn2 phloem sap and lowered (15) N flux to sinks, accompanied by the delayed yellowing (senescence) of asn2 leaves, in the absence of asparagine support a specific role of asparagine in phloem loading and nitrogen reallocation. We conclude that ASN2 is essential for nitrogen assimilation, distribution and remobilization (via the phloem) within the plant. |
| Databáze: | OpenAIRE |
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