Alternative splicing of MaMYB16L regulates starch degradation in banana fruit during ripening
Alternative splicing of MaMYB16L regulates starch degradation in banana fruit during ripening
复制标题
MaMYB16L 的选择性剪接可调节香蕉果实成熟过程中的淀粉降解。
DOI：
10.1111/jipb.13088
复制
发表时间：
2021-04-27
影响因子：
11.4
通讯作者：
Duan, Xuewu
中科院分区：
文献类型：
--
作者：
Jiang, Guoxiang;Zhang, Dandan;Duan, Xuewu
选择基因的选择性剪接是调节植物对内源和环境信号应答的重要机制。然而，选择性剪接在调节果实成熟中的作用仍不清楚。在这里，我们发现，MaMYB 16 L，一个R1型MYB转录因子，进行选择性剪接，并产生两个转录本，全长亚型MaMYB 16 L和截断形式MaMYB 16 S，在香蕉果实。在香蕉果实成熟过程中，选择性剪接过程随着MaMYB 16 L下调和MaMYB 16 S上调而加剧。此外，MaMYB 16 L是一种转录抑制因子，其直接与许多与淀粉降解相关的基因的启动子和MaDREB 2（一种正成熟调节剂）结合，并抑制它们的表达。相比之下，MaMBY 16 S缺乏DNA结合结构域，但与功能性MaMYB 16 L竞争性结合并形成非功能性异二聚体。MaMYB 16 L-MaMYB 16 S异二聚体降低MaMYB 16 L的结合能力和反式阻遏活性。MaMYB 16 L的下调和MaMYB 16 S的上调，即活性与非活性同工型的比率降低，促进成熟相关基因的激活，从而促进果实成熟。此外，MaMYB 16 S的瞬时过表达促进香蕉果实成熟，而MaMYB 16 L的过表达延迟这一过程。因此，MaMYB 16 L的选择性剪接可能产生一个自我控制的调控环来调控香蕉果实的成熟。
The alternative splicing of select genes is an important mechanism to regulate responses to endogenous and environmental signals in plants. However, the role of alternative splicing in regulating fruit ripening remains unclear. Here, we discovered that MaMYB16L, an R1-type MYB transcription factor, undergoes alternative splicing and generates two transcripts, the full-length isoform MaMYB16L and a truncated form MaMYB16S, in banana fruit. During banana fruit ripening, the alternative splicing process intensifies with downregulated MaMYB16L and upregulated MaMYB16S. Moreover, MaMYB16L is a transcriptional repressor that directly binds with the promoters of many genes associated with starch degradation and MaDREB2, a positive ripening regulator, and represses their expression. In contrast, MaMBY16S lacks a DNA-binding domain but competitively combines and forms non-functional heterodimers with functional MaMYB16L. MaMYB16L-MaMYB16S heterodimers decrease the binding capacity and transrepression activity of MaMYB16L. The downregulation of MaMYB16L and the upregulation of MaMYB16S, that is, a decreased ratio of active to non-active isoforms, facilitates the activation of ripening-related genes and thereby promotes fruit ripening. Furthermore, the transient overexpression of MaMYB16S promotes banana fruit ripening, whereas the overexpression of MaMYB16L delays this process. Therefore, the alternative splicing of MaMYB16L might generate a self-controlled regulatory loop to regulate banana fruit ripening.