SUCROSE PHOSPHATE SYNTHASE AND ACID INVERTASE AS DETERMINANTS OF SUCROSE CONCENTRATION IN DEVELOPING MUSKMELON (CUCUMIS-MELO L) FRUITS
SUCROSE PHOSPHATE SYNTHASE AND ACID INVERTASE AS DETERMINANTS OF SUCROSE CONCENTRATION IN DEVELOPING MUSKMELON (CUCUMIS-MELO L) FRUITS
复制标题
DOI：
10.1104/pp.91.4.1527
复制
发表时间：
1989-12-01
期刊：
影响因子：
7.4
通讯作者：
PHARR, DM
中科院分区：
文献类型：
--
作者：
HUBBARD, NL;HUBER, SC;PHARR, DM
以甜瓜（Cucumis melo L.）为研究对象，在甜瓜发育过程中不同的时间收获橙肉甜瓜和绿肉甜瓜的果实，以评估导致蔗糖积累的代谢变化，并确定不同基因型果实蔗糖积累差异的基础。测定蔗糖、棉子糖、己糖和淀粉的浓度，以及蔗糖代谢酶蔗糖磷酸合酶（SPS） （EC 2.4.1.14）、蔗糖合酶（EC 2.4.1.13）、酸性和中性转化酶（EC 3.2.1.26）的活性。蔗糖合酶和中性转化酶活性相对较低(1.7。每克新鲜重量每小时0.3微摩尔和2.2。0.2)，在整个果实发育过程中变化不大。酸转化酶活性在果实发育过程中下降（从每克新鲜重量每小时高达40微摩尔），在成熟的果实中无法检测到活性，而果实中的SPS活性则增加（从每克新鲜重量每小时7微摩尔）到每克新鲜重量每小时高达32微摩尔。积累不同蔗糖量的基因型酸转化酶活性相似，但SPS活性不同。结果表明，酸性转化酶和SPS都是甜瓜果实中蔗糖积累的决定因素。然而，酸转化酶的下降似乎是果实成熟的正常功能，而不是决定蔗糖积累的主要因素。相反，反映在SPS活性上的蔗糖合成能力似乎决定了蔗糖积累，而蔗糖积累是果实品质的重要组成部分。
Fruits of orange-fleshed and green-fleshed muskmelon (Cucumis melo L.) were harvested at different times throughout development to evaluate changes in metabolism which lead to sucrose accumulation, and to determine the basis of differences in fruit sucrose accumulation among genotypes. Concentrations of sucrose, raffinose saccharides, hexoses and starch, as well as activities of the sucrose metabolizing enzyme sucrose phosphate synthase (SPS) (EC 2.4.1.14), sucrose synthase (EC 2.4.1.13), and acid and neutral invertases (EC 3.2.1.26) were measured. Sucrose synthase and neutral invertase activities were relatively low (1.7 .+-. 0.3 micromole per hour per gram fresh weight and 2.2 .+-. 0.2, respectively) and changed little throughout fruit development. Acid invertase activity decreased during fruit development (from as high as 40 micromoles per hour per gram fresh weight) in unripe fruit, to undetectable activity in mature, ripened fruits, while SPS activity in the fruit increased (from 7 micromoles per hour per gram fresh weight) to as high as 32 micromoles per hour per gram fresh weight. Genotypes which accumulated different amounts of sucrose had similar acid invertase activity but differed in SPS activity. Our results indicate that both acid invertase and SPS are determinants of sucrose accumulation in melon fruit. However, the decline in acid invertase appears to be a normal function of fruit maturation, and is not the primary factor which determines sucrose accumulation. Rather, the capacity for sucrose synthesis, reflected in the activity of SPS, appears to determine sucrose accumulation, which is an important component of fruit quality.