番茄不同部位中糖含量和相关酶活性的研究

 试验将番茄光合产物运转途径上叶片(源) 、运输系统以及果实(库) 区分开, 分别测定其糖的组成和含量以及糖代谢相关酶的活性。结果表明: 番茄光合产物运转途径上从“源”到“库”各部位糖的组成和含量不同。叶肉中果糖的含量最高, 蔗糖的含量最低; 中筋中以果糖和葡萄糖为主; 叶柄维管束中葡萄糖含量最高, 蔗糖含量次之, 果糖含量最低。节间和果柄维管束中主要含有蔗糖。果实维管束以及果实内各部位中则主要含有葡萄糖和果糖, 且两者含量无显著差异, 蔗糖含量很低。萼片中葡萄糖含量最高, 蔗糖含量最低; 果蒂中3种糖含量均较高且无显著差异。番茄叶肉及光合产物运转组织中转化酶活性很低, 而在库器官的非维管组织中转化酶活性较高。果蒂中的蔗糖合成酶( SS) 活性最高, 其次是叶肉和运转组织, 果实内各部位中SS活性较低。在合成蔗糖的器官—叶肉中, 有较高的蔗糖磷酸合成酶( SPS) 活性, 运转组织中的SPS活性较叶肉中降低, 但果柄维管束和果实维管束中则表现出较高SPS活性, 果肉、果胶质胎座及心室隔壁中的SPS活性最低。

Studies on Carbohydrate Content and Sucrose-metabolizing Enzymes Activities in Different Parts of Tomato

Tomato leaf (source organ), transport system and fruit (sink organ) were separated along tomato assimilate transport path in order to determinate the composition and content of carbohydrate and sucrose-metabolizing enzymes activities. The results indicated that carbohydrate composition and content and the activities of sucrose-metabolizing enzymes were different at different parts along the transport route from source to sink. Fructose content was the highest, whereas sucrose content was the lowest in mesophyll tissues. Glucose and fructose were the predominant sugars in the midrib of leaf. Glucose was the highest and fructose the lowest in contents in the petiole vascular bundle, with sucrose standing in the medium. Sucrose was the main sugar in the internode and peduncle vascular bundle. In the fruit vascular and other parts of the fruit, glucose and fructose, representing the predominant sugar were nearly equal in amount, with sucrose being present in trace quantities. However, glucose was the highest while sucrose the lowest in contents in sepals. These three kinds of sugar were almost equal in amount in the fruit pedicle. Invertase activity was retained at very lower level in mesophyll and transport tissues. In contrast, in the nonvascular tissues of the sink organ invertase showed higher activity. Among all tissues the activity of sucrose synthase (SS) was the highest in the fruit pedicle and the lowest in the parts of fruits, with mesophyll and transport tissues standing in the medium. Sucrose phosphate synthase (SPS) activity was higher in the mesophyll, the organ of sucrose synthesis, than in transport tissues, except in peduncle and fruit vascular bundles, which favor sucrose synthesis. SPS activity was the lowest at other parts of the fruit.