Devaux Carine, Baldet Pierre, Joubès Jérome, Dieuaide-Noubhani Martine, Just Daniel, Chevalier Christian, Raymond Philippe
Unité Mixte de Recherche en Physiologie et Biotechnologie Végétales, Institut de Biologie Végétale Moléculaire et Institut National de la Recherche Agronomique, Centre de Recherche de Bordeaux, BP 81, F-33883 Villenave d'Ornon Cedex, France.
J Exp Bot. 2003 Apr;54(385):1143-51. doi: 10.1093/jxb/erg113.
Two-month-old tomato plants were submitted to day/night cycles and to prolonged darkness in order to investigate the physiological and biochemical response to sugar starvation in sink organs. Roots appeared particularly sensitive to the cessation of photosynthesis, as revealed by the reduction of the growth rate and the decline of the carbohydrate and protein content. Therefore, excised tomato roots were used as a model to deepen the characterization of sugar starvation symptoms. In excised roots, the endogenous sugars were rapidly exhausted and significant degradation of protein was observed. Glutamine and asparagine accounted for most of the nitrogen released by protein breakdown. Respiration declined and proliferation- and growth-associated genes were repressed soon after the beginning of the sugar depletion. Among the genes studied, only the gene encoding asparagine synthetase was strongly induced. All the starvation symptoms were reversible when the roots were resupplied with sugar. When the culture conditions deteriorated, the metabolic and molecular changes led to the triggering of apoptosis of the root cells.
为了研究库器官对糖饥饿的生理和生化反应，将两个月大的番茄植株置于昼夜循环和长时间黑暗条件下。根系似乎对光合作用的停止特别敏感，这表现为生长速率降低以及碳水化合物和蛋白质含量下降。因此，将离体番茄根用作模型，以深入了解糖饥饿症状的特征。在离体根中，内源糖迅速耗尽，并且观察到蛋白质的显著降解。谷氨酰胺和天冬酰胺占蛋白质分解释放的大部分氮。糖耗尽开始后不久，呼吸作用下降，与增殖和生长相关的基因受到抑制。在所研究的基因中，只有编码天冬酰胺合成酶的基因被强烈诱导。当根系重新供应糖时，所有饥饿症状都是可逆的。当培养条件恶化时，代谢和分子变化导致根细胞凋亡的触发。
