Biological Sciences Center, Desert Research Institute, P. O. Box 60220, Reno, Nevada 89506.
Plant Physiol. 1985 Mar;77(3):617-20. doi: 10.1104/pp.77.3.617.
Phaseolus vulgaris L. leaves were subjected to various light, CO(2), and O(2) levels and abscisic acid, then given a 10 minute pulse of (14)CO(2) followed by a 5 minute chase with unlabeled CO(2). After the chase period, very little label remained in the ionic fractions (presumed to be mostly carbon reduction and carbon oxidation cycle intermediates and amino acids) except at low CO(2) partial pressure. Most label was found in the neutral, alcohol soluble fraction (presumed sucrose) or in the insoluble fraction digestable by amyloglucosidase. Sucrose formation was linearly related to assimilation rate (slope = 0.35). Starch formation increased linearly with assimilation rate (slope = 0.56) but did not occur if the assimilation rate was below 4 micromoles per square meter per second. Neither abscisic acid, nor high CO(2) in combination with low O(2) (thought to disrupt control of carbon metabolism) caused significant perturbations of the sucrose/starch formation ratio. These studies indicate that the pathways for starch and sucrose synthesis both are controlled by the rate of net CO(2) assimilation, with sucrose the preferred product at very low assimilation rates.
菜豆叶片置于不同光照、CO2 和 O2 水平及脱落酸条件下，经 10 分钟 (14)CO2 脉冲标记后，再用未标记的 CO2 追测 5 分钟。在追测期后，除 CO2 分压很低时外，很少有放射性标记留在离子部分（推测主要为碳还原和碳氧化循环中间产物和氨基酸）。大多数标记位于中性、醇溶性部分（推测为蔗糖）或可被淀粉酶消化的不溶部分。蔗糖的形成与同化率呈线性相关（斜率=0.35）。淀粉的形成随同化率呈线性增加（斜率=0.56），但当同化率低于 4 微摩尔/平方米/秒时则不会发生。脱落酸或高 CO2 与低 O2（被认为会破坏碳代谢的控制）联合作用均不会导致蔗糖/淀粉形成比例的显著变化。这些研究表明，淀粉和蔗糖合成的途径均受净 CO2 同化率的控制，在非常低的同化率下，蔗糖是首选产物。
