Research Institute for Photosynthesis, Department of Botany, University of Sheffield, S10 2TN, Sheffield, UK.
Planta. 1985 May;164(2):163-71. doi: 10.1007/BF00396078.
Sap extracted from attached leaves of two-to three-week-old maize plants witt the aid of a roller device was almost devoid of bundle-sheath contamination as judged by the distribution of mesophyll and bundle-sheath markers. The extraction could be done very rapidly (less than 1 s) and the extract immediately quenched in HClO4 or reserved for enzyme assay. Comparison of the contents of metabolites in intact leaves and in the leaf extract allowed estimation of the distribution of metabolites between the bundle-sheath and the mesophyll compartments. Substantial amounts of metabolites such as malate and amino acids were present in the non-photosynthetic cells of the midrib. In the illuminated leaf, triose phosphate was predominantly located outside the bundle-sheath while the major part of the 3-phosphoglycerate was in the bundle sheath. The results indicate the existence of concentration gradients of triose phosphate and 3-phosphoglycerate in the leaf which are capable of maintaining carbon flow between the mesophyll and bundle-sheath cells during photosynthesis. There was no evidence for the existence of a gradient of pyruvate between the bundle-sheath and the mesophyll cells.
用滚子设备从两周至三周大的玉米植株的附着叶片中提取的汁液，几乎没有束鞘污染，这可以根据叶肉和束鞘标记物的分布来判断。提取可以非常迅速地完成（不到 1 秒），并且提取液可以立即用 HClO4 淬灭或保留用于酶测定。比较完整叶片和叶片提取物中的代谢物含量，可以估计代谢物在束鞘和叶肉细胞之间的分布。大量的代谢物，如苹果酸和氨基酸，存在于中脉的非光合细胞中。在照光的叶片中，三碳糖磷酸主要位于束鞘之外，而 3-磷酸甘油酸的主要部分位于束鞘中。这些结果表明，在叶片中存在三碳糖磷酸和 3-磷酸甘油酸的浓度梯度，这些梯度能够在光合作用过程中维持碳在叶肉细胞和束鞘细胞之间的流动。没有证据表明在束鞘和叶肉细胞之间存在丙酮酸梯度。
