Plant Photobiology Laboratory, Plant Physiology Institute, Beltsville, Maryland 20705.
Plant Physiol. 1985 Nov;79(3):838-42. doi: 10.1104/pp.79.3.838.
The flow of carbon into sucrose and starch was investigated in fully expanded primary leaves of spinach using the long to short day transition and partial defoliation as tools to manipulate sucrose/starch synthesis. Transfer from 12 hour to 7 hour photosynthetic periods resulted in a 4-fold increase in the initial rate of starch synthesis, a 50% increase in the initial rate of sucrose synthesis, a 30% increase in leaf sucrose, and a 40% decrease in fructose, 2,6-biphosphate. In addition, sucrose synthesis rates in cells isolated from shortened daylength plants are 80% higher than in cells isolated from control plants. These results show that, in spinach, an increase in the rates of both sucrose and starch synthesis can occur under short day conditions. In contrast, when short day plants are partially defoliated, starch levels remain high, fructose 2,6-biphosphate levels remain low, but the level of leaf sucrose drops by 50%. Thus, when demand exceeds supply, starch synthesis has priority over filling of leaf sucrose pools in the short day plant.
采用长日至短日转变和部分摘叶作为工具，研究了菠菜完全展开的初生叶片中碳向蔗糖和淀粉的流动。从 12 小时光合作用期转变为 7 小时光合作用期，导致淀粉合成的初始速率增加了 4 倍，蔗糖合成的初始速率增加了 50%，叶片蔗糖增加了 30%，果糖 2,6-二磷酸减少了 40%。此外，从短日植物中分离出的细胞的蔗糖合成速率比从对照植物中分离出的细胞高 80%。这些结果表明，在菠菜中，短日条件下可以同时提高蔗糖和淀粉的合成速率。相比之下，当短日植物部分摘叶时，淀粉水平仍然很高，果糖 2,6-二磷酸水平仍然很低，但叶片蔗糖水平下降了 50%。因此，当需求超过供应时，淀粉合成优先于短日植物中叶片蔗糖池的填充。
