Overexpression of sugar transporter gene PbSWEET4 of pear causes sugar reduce and early senescence in leaves
Overexpression of sugar transporter gene PbSWEET4 of pear causes sugar reduce and early senescence in leaves
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梨糖转运蛋白基因PbSWEET4过表达导致叶片糖分降低和早衰
DOI：
10.1016/j.gene.2020.144582
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发表时间：
2020-06-15
期刊：
影响因子：
3.5
通讯作者：
Wu, Jun
中科院分区：
文献类型：
--
作者：
Ni, Jiangping;Li, Jiaming;Wu, Jun
糖是植物生长发育过程中合成三磷酸腺苷的主要能量来源，而糖的分配依赖于不同细胞器之间的细胞内运输和源库运输。然而，目前对梨糖运输的相关研究还很有限。在此，我们发现了一个糖转运蛋白PbSWEET4，它可以控制叶片中的糖含量和衰老。系统发育分析和多序列比对结果表明，PbSWEET4与AtSWEETI5同源，含有两个保守结构域，可促进衰老。QRT-PCR和转录组数据库结果表明，PbSWEET4的表达与叶片发育呈正相关，尤其是在老叶中高表达。此外，对启动子-GUS活性的评估也表明，PbSWEET4在老叶中的表达水平最高。亚细胞定位显示PbSWEET4定位于细胞膜。最后，PbSWEET4在草莓植株中的过表达可降低叶片含糖量和叶绿素含量，加速叶片衰老，这可能是由于叶片糖的输出增加所致。这些结果丰富了糖输出子在果树发育调控中的作用，为今后梨树等果树碳水化合物分配的改良提供了新的遗传资源。
As the main energy source for generating ATP during plant growth and development, sugars are synthesized in leaves, while sugar allocation depends on both intracellular transport between different organelles and sourceto-sink transport. However, sugar transport related research is limited in pear. Here, a sugar transporter PbSWEET4 was identified that control sugar content and senescence in leaf. Phylogenetic analysis and multiple sequence alignment results indicated that PbSWEET4 was homologous to AtSWEETI5, which contained two conserved domains and could promote senescence. The qRT-PCR and transcriptome database result showed that the expression of PbSWEET4 was positively correlated with leaf development, especially highly expressed in older leaves. Furthermore, the evaluation of promoter-GUS activity also indicated that PbSWEET4 exhibited the highest expression level in older leaves. The subcellular localization revealed that the PbSWEET4 localized in the plasma membrane. Finally, overexpression of the PbSWEET4 in strawberry plants could reduce leaf sugar content and chlorophyll content, while accelerate leaf senescence, which might be due to enhanced export of sugars from leaves. These results enrich the knowledge about the function of sugar exporter in regulating the fruit species development, and provide a novel genetic resource for future improvement in carbohydrate partitioning for pear and other fruit trees.