Martin T, Frommer W B, Salanoubat M, Willmitzer L
Institut für Genbiologische Forschung Berlin GmbH, Berlin, Germany.
Plant J. 1993 Aug;4(2):367-77. doi: 10.1046/j.1365-313x.1993.04020367.x.
Sucrose synthase, an important enzyme in carbohydrate metabolism, catalyzes the reversible conversion of sucrose and UDP to UDP-glucose and fructose in vitro. To investigate the in vivo function of sucrose synthase, both the gene (Asus1) and a corresponding cDNA from roots of Arabidopsis were isolated. The Asus1 gene has homologies of 67-72% to sucrose synthase genes from other species. Histochemical GUS analysis of Arabidopsis and tobacco plants transformed with a 1.5 kb Asus1 promoter fragment transcriptionally fused to the beta-glucuronidase reporter gene showed that the Asus1 gene is expressed in the phloem of leaves, and in roots. Induction is found under conditions of limited ATP supply and increased demand for translocation of carbohydrates such as anaerobic or cold treatment. During anaerobiosis the increase in RNA level leads to increased sucrose synthase activity in roots. The expression pattern and regulation of the gene suggest that sucrose synthase is involved in the supply of energy for phloem loading in source tissues, and in metabolization of sucrose in sink tissues after unloading.
蔗糖合酶是碳水化合物代谢中的一种重要酶，在体外催化蔗糖和UDP可逆转化为UDP-葡萄糖和果糖。为了研究蔗糖合酶的体内功能，从拟南芥根中分离出了该基因（Asus1）及其相应的cDNA。Asus1基因与其他物种的蔗糖合酶基因具有67%-72%的同源性。对用与β-葡萄糖醛酸酶报告基因转录融合的1.5 kb Asus1启动子片段转化的拟南芥和烟草植株进行组织化学GUS分析表明，Asus1基因在叶和根的韧皮部中表达。在ATP供应有限以及碳水化合物转运需求增加的条件下，如厌氧或冷处理，可发现该基因被诱导表达。在无氧状态下，RNA水平的增加导致根中蔗糖合酶活性增强。该基因的表达模式和调控表明，蔗糖合酶参与源组织中韧皮部装载的能量供应以及卸载后库组织中蔗糖的代谢。
