Grimm Eckhard, Pflugfelder Daniel, Hahn Jan, Schmidt Moritz Jonathan, Dieckmann Hendrik, Knoche Moritz
1Institut für Gartenbauliche Produktionssysteme, Leibniz Universität Hannover, Abteilung Obstbau, Herrenhäuser Straße 2, D-30419 Hannover, Germany.
2Forschungszentrum Jülich, IBG-2: Pflanzenwissenschaften, Wilhelm-Johnen-Straße, D-52428 Jülich, Germany.
Hortic Res. 2020 Apr 1;7:51. doi: 10.1038/s41438-020-0274-8. eCollection 2020.
A fleshy fruit is commonly assumed to resemble a thin-walled pressure vessel containing a homogenous carbohydrate solution. Using sweet cherry ( L.) as a model system, we investigate how local differences in cell water potential affect HO and DO (heavy water) partitioning. The partitioning of HO and DO was mapped non-destructively using magnetic resonance imaging (MRI). The change in size of mesocarp cells due to water movement was monitored by optical coherence tomography (OCT, non-destructive). Osmotic potential was mapped using micro-osmometry (destructive). Virtual sections through the fruit revealed that the HO distribution followed a net pattern in the outer mesocarp and a radial pattern in the inner mesocarp. These patterns align with the disposition of the vascular bundles. DO uptake through the skin paralleled the acropetal gradient in cell osmotic potential gradient (from less negative to more negative). Cells in the vicinity of a vascular bundle were of more negative osmotic potential than cells more distant from a vascular bundle. OCT revealed net HO uptake was the result of some cells loosing volume and other cells increasing volume. HO and DO partitioning following uptake is non-uniform and related to the spatial heterogeneity in the osmotic potential of mesocarp cells.
肉质果实通常被认为类似于一个薄壁压力容器，其中含有均匀的碳水化合物溶液。以甜樱桃（L.）为模型系统，我们研究了细胞水势的局部差异如何影响H₂O和D₂O（重水）的分配。使用磁共振成像（MRI）对H₂O和D₂O的分配进行无损映射。通过光学相干断层扫描（OCT，无损）监测由于水分移动导致的中果皮细胞大小变化。使用微渗透压测定法（有损）绘制渗透势图。果实的虚拟切片显示，H₂O分布在外中果皮呈网状模式，在内中果皮呈径向模式。这些模式与维管束的分布一致。通过果皮的D₂O吸收与细胞渗透势梯度的向顶梯度平行（从较低负值到较高负值）。维管束附近的细胞比远离维管束的细胞具有更负的渗透势。OCT显示净H₂O吸收是一些细胞体积减小而其他细胞体积增加的结果。吸收后H₂O和D₂O的分配不均匀，并且与中果皮细胞渗透势的空间异质性有关。
