开花是植物生长发育的重要环节，开花时间与种子、果实的发育及作物产量的形成直接相关。microRNA（miRNA）加工和pre-mRNA剪接都参与开花时间的调控。但人们对植物如何协同pre-mRNA的剪接和miRNA的加工调节开花时间还不了解。我们前期的研究发现一个调控拟南芥开花时间的基因AtSF3B1，编码的蛋白与酵母和人剪接体U2 snRNP核心组分Hsh155/SF3B1在功能上同源；AtSF3B1参与开花关键抑制基因FLC的pre-mRNA剪接；同时AtSF3B1和参与miRNA加工的DAWDLE互作。以上结果暗示AtSF3B1除参与pre-mRNA剪接外还在miRNA加工中起作用。本课题计划在研究AtSF3B1参与miRNA加工分子机制的基础上，探讨AtSF3B1协同调节pre-mRNA剪接和miRNA加工参与植物开花转变的作用机理。

Flowering is a critical step for plant development. Flowering transition is directly related to the development of seed and fruit, and yield formation of crop. Processing of microRNA (miRNA) and splicing of pre-mRNA function in the regulation of flowering time. However, the mechanism of coordinative regulation between them in flowering transition is not yet clarified. In our study, we identified an Arabidopsis gene, AtSF3B1, involved in flowering transition as a negative regulator, which encodes a functional homolog of U2 snRNP component of yeast Hsh155 and human SF3B1. The splicing of FLC, a key regulator of flowering time, was compromised in the atsf3b1 mutants. Additionally, we found that AtSF3B1 was interacted with DAWDLE, a RNA-binding protein which is required for miRNA processing. The mRNA accumulations of target genes of miR156 and miR172, two key miRNAs related to flowering, were altered in the atsf3b1 mutants. These results indicate that AtSF3B1 is implicated in miRNA processing, as well as pre-mRNA splicing. In this project, we plan to study the molecular mechanism of AtSF3B1 regulating flowering transition by coordinately modulating pre-mRNA splicing and miRNA processing.