Trevanion S J
IACR-Rothamsted, Harpenden, Herts. AL5 2JQ, UK.
J Exp Bot. 2000 Jun;51(347):1037-45. doi: 10.1093/jexbot/51.347.1037.
The accurate measurement of fructose 2,6-bisphosphate from plants such as wheat is fraught with difficulty. Extraction and assay methods for fructose 2,6-bisphosphate that give near 100% recovery of the metabolite, and a linear response with volume have therefore been developed for extracts prepared from wheat leaves of different ages. Amounts of fructose 2,6-bisphosphate in different regions of leaves generally showed a positive correlation with chlorophyll content. Measurements of sucrose and starch in third leaves harvested at different times of the diurnal cycle demonstrated that sucrose is the major form in which photosynthate is stored in the leaf, but starch can account for up to about 30% of the stored carbohydrate. Virtually all of the carbohydrate accumulated as starch and sucrose during the day was degraded at night. Amounts of fructose 2,6-bisphosphate were generally lower in extracts prepared from leaves harvested in the light than in the dark. Additionally, there was no change in either the amount of fructose 2, 6-bisphosphate or the ratio of sucrose to starch in samples prepared from leaves harvested at different times of the day. These results are broadly consistent with a role for fructose 2,6-bisphosphate in the regulation of sucrose synthesis and the partitioning of carbohydrate between sucrose and starch in wheat leaves.
准确测量小麦等植物中的果糖-2,6-二磷酸存在诸多困难。因此，针对不同年龄小麦叶片提取物，已开发出能使代谢物回收率接近100%且对体积呈线性响应的果糖-2,6-二磷酸提取和测定方法。叶片不同区域的果糖-2,6-二磷酸含量通常与叶绿素含量呈正相关。对昼夜周期不同时间收获的第三片叶子中的蔗糖和淀粉进行测量表明，蔗糖是光合产物在叶片中储存的主要形式，但淀粉可占储存碳水化合物的约30%。白天积累为淀粉和蔗糖的几乎所有碳水化合物在夜间都会降解。从光照下收获的叶片制备的提取物中，果糖-2,6-二磷酸的含量通常低于黑暗中收获的叶片提取物。此外，从一天中不同时间收获的叶片制备的样品中，果糖-2,6-二磷酸的含量或蔗糖与淀粉的比例均无变化。这些结果与果糖-2,6-二磷酸在调节蔗糖合成以及小麦叶片中碳水化合物在蔗糖和淀粉之间的分配方面所起的作用大致相符。
