Université de Poitiers, UMR CNRS 7267 EBI Ecologie et Biologie des Interactions, Equipe "Sucres & Echanges Végétaux-Environnement", Bâtiment B31, 3 rue Jacques Fort, TSA 51106, 86073, Poitiers Cedex 9, France.
Planta. 2018 Mar;247(3):587-611. doi: 10.1007/s00425-017-2807-4. Epub 2017 Nov 14.
The regulation of source-to-sink sucrose transport is associated with AtSUC and AtSWEET sucrose transporters' gene expression changes in plants grown hydroponically under different physiological conditions. Source-to-sink transport of sucrose is one of the major determinants of plant growth. Whole-plant carbohydrates' partitioning requires the specific activity of membrane sugar transporters. In Arabidopsis thaliana plants, two families of transporters are involved in sucrose transport: AtSUCs and AtSWEETs. This study is focused on the comparison of sucrose transporter gene expression, soluble sugar and starch levels and long distance sucrose transport, in leaves and sink organs (mainly roots) in different physiological conditions (along the plant life cycle, during a diel cycle, and during an osmotic stress) in plants grown hydroponically. In leaves, the AtSUC2, AtSWEET11, and 12 genes known to be involved in phloem loading were highly expressed when sucrose export was high and reduced during osmotic stress. In roots, AtSUC1 was highly expressed and its expression profile in the different conditions tested suggests that it may play a role in sucrose unloading in roots and in root growth. The SWEET transporter genes AtSWEET12, 13, and 15 were found expressed in all organs at all stages studied, while differential expression was noticed for AtSWEET14 in roots, stems, and siliques and AtSWEET9, 10 expressions were only detected in stems and siliques. A role for these transporters in carbohydrate partitioning in different source-sink status is proposed, with a specific attention on carbon demand in roots. During development, despite trophic competition with others sinks, roots remained a significant sink, but during osmotic stress, the amount of translocated [U-C]-sucrose decreased for rosettes and roots. Altogether, these results suggest that source-sink relationship may be linked with the regulation of sucrose transporter gene expression.
在不同生理条件下水培生长的植物中，源-库蔗糖转运的调节与 AtSUC 和 AtSWEET 蔗糖转运体基因表达变化有关。蔗糖的源-库转运是植物生长的主要决定因素之一。整个植物的碳水化合物分配需要膜糖转运体的特定活性。在拟南芥植物中，有两类转运体参与蔗糖转运：AtSUCs 和 AtSWEETs。本研究集中比较了蔗糖转运体基因表达、可溶性糖和淀粉水平以及长距离蔗糖转运在不同生理条件下（沿植物生命周期、昼夜周期和渗透胁迫）水培生长的叶片和库器官（主要是根）中的差异。在叶片中，已知参与韧皮部装载的 AtSUC2、AtSWEET11 和 12 基因在蔗糖外排高时高度表达，而在渗透胁迫时表达减少。在根中，AtSUC1 高度表达，其在不同条件下的表达谱表明它可能在根中的蔗糖卸载和根生长中发挥作用。在所有研究的器官和阶段中，都发现 SWEET 转运体基因 AtSWEET12、13 和 15 表达，而在根、茎和蒴果中观察到 AtSWEET14 的差异表达，在茎和蒴果中仅检测到 AtSWEET9、10 的表达。提出了这些转运体在不同源-库状态下碳水化合物分配中的作用，特别关注根中的碳需求。在发育过程中，尽管与其他库存在营养竞争，但根仍然是一个重要的库，但在渗透胁迫下，转移的 [U-C]-蔗糖的量减少了。总的来说，这些结果表明源-库关系可能与蔗糖转运体基因表达的调节有关。
