AtSWEET4, a hexose facilitator, mediates sugar transport to axial sinks and affects plant development.
AtSWEET4, a hexose facilitator, mediates sugar transport to axial sinks and affects plant development.
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DOI：
10.1038/srep24563
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发表时间：
2016-04-22
影响因子：
4.6
通讯作者：
Li J
中科院分区：
文献类型：
--
作者：
Liu X;Zhang Y;Yang C;Tian Z;Li J
植物通过韧皮部易位途径将光同化物从源器官运输到库组织。在运输韧皮部中，从筛管逸出的糖在长距离运输过程中被释放到筛元件/伴细胞复合物（SE/CC）和韧皮部薄壁细胞（PPC）之间的质外质空间中。 SE/CC 和相邻 PPC 之间对糖获取的竞争是由质膜易位蛋白介导的。 YFP标记的AtSWEET4蛋白定位于质膜，PromoterAtSWEET4-GUS分析表明，AtSWEET4在叶和花的根、脉中表达。 AtSWEET4 在拟南芥中的过度表达会增加植物的大小并积累更多的葡萄糖和果糖。相比之下，通过RNA干扰敲低AtSWEET4会导致植株变小、葡萄糖和果糖含量减少、叶脉网络失绿以及叶子叶绿素含量减少。酵母检测表明 AtSWEET4 能够弥补果糖和葡萄糖转运缺陷。 AtSWEET4 过表达的转基因植物表现出更高的冷冻耐受性并支持细菌丁香假单胞菌 pv. 的更多生长。菜豆 NPS3121。我们得出结论，AtSWEET4 在植物生长和发育过程中介导轴向组织糖转运中发挥重要作用。
Plants transport photoassimilates from source organs to sink tissues through the phloem translocation pathway. In the transport phloem, sugars that escape from the sieve tubes are released into the apoplasmic space between the sieve element/companion cell complex (SE/CC) and phloem parenchyma cells (PPCs) during the process of long-distance transport. The competition for sugar acquisition between SE/CC and adjoining PPCs is mediated by plasma membrane translocators. YFP-tagged AtSWEET4 protein is localized in the plasma membrane, and PromoterAtSWEET4-GUS analysis showed that AtSWEET4 is expressed in the stele of roots and veins of leaves and flowers. Overexpression of AtSWEET4 in Arabidopsis increases plant size and accumulates more glucose and fructose. By contrast, knock-down of AtSWEET4 by RNA-interference leads to small plant size, reduction in glucose and fructose contents, chlorosis in the leaf vein network, and reduction in chlorophyll content in leaves. Yeast assays demonstrated that AtSWEET4 is able to complement both fructose and glucose transport deficiency. Transgenic plants of AtSWEET4 overexpression exhibit higher freezing tolerance and support more growth of bacterium Pseudomonas syringae pv. phaseolicola NPS3121. We conclude that AtSWEET4 plays an important role in mediating sugar transport in axial tissues during plant growth and development.