State Key Laboratory of Crop Stress Biology in Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Xianyang, China.
College of Life Science, Northwest A&F University, Xianyang, China.
Nat Plants. 2023 Jun;9(6):951-964. doi: 10.1038/s41477-023-01443-8. Epub 2023 Jun 8.
Soluble sugars are the core components of fruit quality, and the degree of sugar accumulation is largely determined by tonoplast-localized sugar transporters. We previously showed that two classes of tonoplast sugar transporters, MdERDL6 and MdTST1/2, coordinately regulate sugar accumulation in vacuoles. However, the mechanism underlying this coordination remains unknown. Here we discovered that two transcription factors, MdAREB1.1/1.2, regulate MdTST1/2 expression by binding their promoters in apple. The enhanced MdAREB1.1/1.2 expression in MdERDL6-1-overexpression plants resulted in an increase in MdTST1/2 expression and sugar concentration. Further studies established that MdSnRK2.3, whose expression could be regulated by expressing MdERDL6-1, could interact with and phosphorylate MdAREB1.1/1.2, thereby promoting the MdAREB1.1/1.2-mediated transcriptional activation of MdTST1/2. Finally, the orthologous SlAREB1.2 and SlSnRK2.3 exhibited similar functions in tomato fruit as in their apple counterparts. Together, our findings provide insights into the regulatory mechanism of tonoplast sugar transport exerted by SnRK2.3-AREB1-TST1/2 for fruit sugar accumulation.
可溶性糖是果实品质的核心成分，糖的积累程度在很大程度上取决于液泡膜定位的糖转运蛋白。我们之前的研究表明，两类液泡膜糖转运蛋白 MdERDL6 和 MdTST1/2 协同调节液泡中糖的积累。然而，这种协调的机制尚不清楚。在这里，我们发现两个转录因子 MdAREB1.1/1.2 通过结合其在苹果中的启动子来调节 MdTST1/2 的表达。在 MdERDL6-1 过表达植株中增强的 MdAREB1.1/1.2 表达导致 MdTST1/2 表达和糖浓度增加。进一步的研究表明，其表达可受 MdERDL6-1 调控的 MdSnRK2.3 可以与 MdAREB1.1/1.2 相互作用并磷酸化它，从而促进 MdAREB1.1/1.2 介导的 MdTST1/2 的转录激活。最后，在番茄果实中，同源的 SlAREB1.2 和 SlSnRK2.3 表现出与苹果对应物相似的功能。总之，我们的研究结果为 SnRK2.3-AREB1-TST1/2 对果实糖积累的液泡糖转运的调控机制提供了新的见解。
