Spatial analysis of plant metabolism:: Sucrose imaging within Vicia faba cotyledons reveals specific developmental patterns
Spatial analysis of plant metabolism:: Sucrose imaging within Vicia faba cotyledons reveals specific developmental patterns
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DOI：
10.1046/j.1365-313x.2002.01222.x
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发表时间：
2002-02-01
期刊：
影响因子：
7.2
通讯作者：
Weber, H
中科院分区：
文献类型：
--
作者：
Borisjuk, L;Walenta, S;Weber, H
在豆科植物胚胎发生过程中，子叶的分化以波状方式逐渐进行。该过程受到糖的代谢和遗传控制和调节。为了对糖分布模式进行空间和时间分析，开发了一种新方法，通过生物发光和单光子计数直接专门测量组织中的蔗糖。这使得定量蔗糖成像的分辨率接近单细胞水平。该程序应用于涵盖组织分化主要阶段的蚕豆子叶切片，储存期前的幼胚含有中等水平的蔗糖，且分布均匀。在成熟开始时，覆盖子叶外侧一半的组织层内存在高浓度。该层位于表达蔗糖转运蛋白基因的表皮正下方，表明表皮转运蛋白导致下面组织中蔗糖的高积累。在该阶段，与细胞大小和淀粉含量相比，蔗糖梯度呈相反方向。内部细胞较大，含有淀粉但蔗糖含量低。因此，蔗糖模式是由实质内的吸收活性和渗透性控制的。然而，在主要储存阶段，积极伸长和淀粉积累的细胞含有最高的蔗糖浓度，表明生长和淀粉积累的差异也会影响子叶内糖的分布。高蔗糖浓度与蔗糖合酶和ADP-Glc焦磷酸化酶的转录水平相关，表明蔗糖在基因表达水平上具有诱导淀粉生物合成的信号传导功能。当己糖水平降低时，通过蔗糖合酶途径流向淀粉的碳通量增加。
During legume embryogenesis the differentiation of the cotyledons proceeds gradually in a wave-like manner. The process is metabolically and genetically controlled and regulated by sugars. In order to perform a spatial and temporal analysis of the sugar distribution pattern a new method was developed to specifically measure sucrose directly in tissues via bioluminescence and single photon counting. This enabled a quantitative sucrose imaging with a resolution close to the single cell level. The procedure was applied on sections of Vicia faba cotyledons covering the main stages of histodifferentiation, Young embryos before the storage phase contained moderate levels of sucrose, which were evenly distributed. At the onset of maturation high concentrations were present within a tissue layer covering the outwarded half of the coytledons. This layer was directly underneath the epidermis expressing a sucrose transporter gene indicating that epidermal transporters caused the high sucrose accumulation in the underlying tissue. At that stage the sucrose gradient was inversely oriented compared with cell size and the starch content. Cells within the interior were larger, contained starch but low sucrose. Thus, the sucrose pattern is controlled by uptake activity and permeability within the parenchyma. However, during the main storage phase actively elongating and starch accumulating cells contain highest sucrose concentrations indicating that differences in growth and starch accumulation also affect intracotyledonary sugar distribution. High sucrose concentrations were correlated with transcript levels of sucrose synthase and ADP-Glc pyrophosphorylase indicating a signaling function for sucrose to induce starch biosynthesis on the gene expression level. Carbon flux through the sucrose synthase pathway towards starch increased when hexoses levels decreased.