Department of Biological Sciences, Wellesley College, Wellesley, Massachusetts 02181.
Plant Physiol. 1986 Dec;82(4):1081-9. doi: 10.1104/pp.82.4.1081.
When intact corn leaves were provided millimolar concentrations of d-mannose through the transpiration stream photosynthesis was inhibited; 5.7 millimolar resulted in a 50% inhibition of the carbon exchange rate. This inhibition was partially reversible by the addition of orthophosphate to the feeding solution. Mannose metabolism by corn leaves was limited in that it did not act as a resource for sucrose or starch synthesis. Mannose 6-phosphate accumulated in the leaf tissues and was slowly metabolized by a pathway involving mannose 1-phosphate. Correlated with the mannose-6-phosphate accumulation were decreases in ATP, orthophosphate, sucrose, and phosphoenolpyruvate and increases in starch and maltose. When provided in the transpiration stream mannose had access to both mesophyll and bundle sheath cells. Mannose feeding led to oscillations in steady state chlorophyll fluorescence emission (680 nanometers) and an elimination of the Kautsky effect during fluorescence induction. Pyridoxal 5-phosphate and 2,4-dinitrophenol were found to be inhibitors of CO(2) exchange when provided in the transpiration stream of intact corn leaves. However, Pyridoxal 5-phosphate induced a quenching of steady state fluorescence while 2,4-dinitrophenol led to an increase in fluorescence emission.
当完整的玉米叶片通过蒸腾流提供毫摩尔浓度的 D-甘露糖时，光合作用受到抑制；5.7 毫摩尔导致碳交换率抑制 50%。通过向进料溶液中添加正磷酸盐，这种抑制作用部分可逆。玉米叶片的甘露糖代谢受到限制，因为它不能作为蔗糖或淀粉合成的资源。甘露糖 6-磷酸在叶片组织中积累，并通过涉及甘露糖 1-磷酸的途径缓慢代谢。与甘露糖-6-磷酸积累相关的是 ATP、正磷酸盐、蔗糖和磷酸烯醇丙酮酸的减少，以及淀粉和麦芽糖的增加。当甘露糖在蒸腾流中提供时，它可以进入叶肉细胞和束鞘细胞。甘露糖喂养导致稳态叶绿素荧光发射（680 纳米）的振荡，并在荧光诱导期间消除 Kautsky 效应。发现吡哆醛 5-磷酸和 2,4-二硝基苯酚在完整玉米叶片的蒸腾流中提供时是 CO2 交换的抑制剂。然而，吡哆醛 5-磷酸诱导稳态荧光猝灭，而 2,4-二硝基苯酚导致荧光发射增加。
