Centre of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.
Centre of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.
Gene. 2020 Jun 15;743:144582. doi: 10.1016/j.gene.2020.144582. Epub 2020 Mar 12.
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 source-to-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 AtSWEET15, 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.
作为植物生长发育过程中生成 ATP 的主要能量来源，糖在叶片中合成，而糖的分配取决于不同细胞器之间的细胞内运输和源到库的运输。然而，关于糖运输的相关研究在梨中是有限的。在这里，鉴定到一个与叶片中糖含量和衰老有关的糖转运蛋白 PbSWEET4。系统进化分析和多重序列比对结果表明，PbSWEET4与 AtSWEET15 同源，它含有两个保守结构域，能够促进衰老。qRT-PCR 和转录组数据库的结果表明，PbSWEET4 的表达与叶片发育呈正相关，特别是在较老的叶片中高度表达。此外，对启动子-GUS 活性的评估也表明，PbSWEET4 在较老的叶片中表现出最高的表达水平。亚细胞定位表明 PbSWEET4 定位于质膜上。最后，在草莓植株中过表达 PbSWEET4 可以降低叶片中的糖含量和叶绿素含量，同时加速叶片衰老，这可能是由于叶片中糖的输出增强所致。这些结果丰富了糖输出器在调节果实种发育功能方面的知识，并为未来提高梨和其他果树的碳水化合物分配提供了新的遗传资源。
