Leaf Fructose Content Is Controlled by the Vacuolar Transporter SWEET17 in Arabidopsis
Leaf Fructose Content Is Controlled by the Vacuolar Transporter SWEET17 in Arabidopsis
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DOI：
10.1016/j.cub.2013.03.021
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发表时间：
2013-04-22
期刊：
影响因子：
9.2
通讯作者：
Krapp, Anne
中科院分区：
文献类型：
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作者：
Chardon, Fabien;Bedu, Magali;Krapp, Anne
在高等植物中，可溶性糖主要以蔗糖、葡萄糖和果糖的形式存在。糖的分配基于不同细胞器之间的源到库运输和细胞内运输[2，3]，并取决于植物的实际需求[4]。在非生物胁迫条件下，如氮素限制，碳水化合物在植物细胞中积累[5]。尽管越来越多的遗传研究[6，7]，但决定碳水化合物组成的遗传结构却鲜为人知。利用数量遗传学方法，我们确定载体蛋白SWEET17是控制拟南芥叶片果糖含量的主要因素。我们观察到，当SWEET17的表达降低时，无论是通过诱导或自然变异，果糖在叶片中积累，这表明存储能力增强。SWEET17-GFP的液泡膜亚细胞定位及其在非洲爪哇卵母细胞中的功能表达表明，SWEET17是第一个在植物中鉴定的液泡型果糖转运蛋白。植物中的生理学研究提供了SWEET17从液泡中输出果糖的证据。总体而言，我们的结果表明，叶片果糖水平的自然变化是由液泡果糖转运蛋白SWEET17控制的。SWEET17在整个植物界高度保守；因此，这些发现为未来改变作物中的碳水化合物分配提供了可能性。
In higher plants, soluble sugars are mainly present as sucrose, glucose, and fructose [1]. Sugar allocation is based on both source-to-sink transport and intracellular transport between the different organelles [2,3] and depends on actual plant requirements [4]. Under abiotic stress conditions, such as nitrogen limitation, carbohydrates accumulate in plant cells [5]. Despite an increasing number of genetic studies [6, 7], the genetic architecture determining carbohydrate composition is poorly known. Using a quantitative genetics approach, we determined that the carrier protein SWEET17 is a major factor controlling fructose content in Arabidopsis leaves. We observed that when SWEET17 expression is reduced, either by induced or natural variation, fructose accumulates in leaves, suggesting an enhanced storage capacity. Subcellular localization of SWEET17-GFP to the tonoplast and functional expression in Xenopus oocytes showed that SWEET17 is the first vacuolar fructose transporter to be characterized in plants. Physiological studies in planta provide evidence that SWEET17 acts to export fructose out of the vacuole. Overall, our results suggest that natural variation in leaf fructose levels is controlled by the vacuolar fructose transporter SWEET17. SWEET17 is highly conserved across the plant kingdom; thus, these findings offer future possibilities to modify carbohydrate partitioning in crops.