Koroleva OA, Farrar JF, Pollock CJ
School of Biological Sciences, University of Wales, Bangor, Gwynedd, Wales, United Kingdom (O.A.K., J.F.F., A.D.T.).
Plant Physiol. 1998 Dec;118(4):1525-32. doi: 10.1104/pp.118.4.1525.
Carbohydrate metabolism of barley (Hordeum vulgare) leaves induced to accumulate sucrose (Suc) and fructans was investigated at the single-cell level using single-cell sampling and analysis. Cooling of the root and shoot apical meristem of barley plants led to the accumulation of Suc and fructan in leaf tissue. Suc and fructan accumulated in both mesophyll and parenchymatous bundle-sheath (PBS) cells because of the reduced export of sugars from leaves under cooling and to increased photosynthesis under high photon fluence rates. The general trends of Suc and fructan accumulation were similar for mesophyll and PBS cells. The fructan-to-Suc ratio was higher for PBS cells than for mesophyll cells, suggesting that the threshold Suc concentration needed for the initiation of fructan synthesis was lower for PBS cells. Epidermal cells contained very low concentrations of sugar throughout the cooling experiment. The difference in Suc concentration between control and treated plants was much less if compared at the single-cell level rather than the whole-tissue level, suggesting that the vascular tissue contains a significant proportion of total leaf Suc. We discuss the importance of analyzing complex tissues at the resolution of individual cells to assign molecular mechanisms to phenomena observed at the whole-plant level.
利用单细胞采样和分析技术，在单细胞水平上研究了诱导积累蔗糖（Suc）和果聚糖的大麦（Hordeum vulgare）叶片的碳水化合物代谢。对大麦植株的根和茎顶端分生组织进行冷却处理，导致叶片组织中蔗糖和果聚糖积累。由于冷却条件下叶片糖分输出减少以及高光量子通量率下光合作用增强，蔗糖和果聚糖在叶肉细胞和薄壁束鞘（PBS）细胞中均有积累。叶肉细胞和PBS细胞中蔗糖和果聚糖积累的总体趋势相似。PBS细胞中果聚糖与蔗糖的比值高于叶肉细胞，这表明PBS细胞启动果聚糖合成所需的阈值蔗糖浓度较低。在整个冷却实验过程中，表皮细胞中的糖分浓度非常低。与全组织水平相比，在单细胞水平上比较对照植株和处理植株之间的蔗糖浓度差异要小得多，这表明维管组织中含有叶片总蔗糖的很大一部分。我们讨论了在单个细胞分辨率下分析复杂组织对于将分子机制与在全株水平上观察到的现象相关联的重要性。
