miRNA是单链非编码小RNA，通过沉默其靶基因控制植物发育和适应。miRNA生物合成调控机制已取得重要进展，但很多问题急需解决。在前期研究中，我们发现了一个剪切因子RBM25，调控PP2C家族基因HAB1 pre-mRNA可变剪切体的比例和植物对ABA的响应。有意思的是RBM25也影响pri-miRNA稳定性。更重要的是RBM25与pri-miRNA加工核心组分HYL1互作，表明它在pri-miRNA加工剪切中的重要作用，但背后机制尚不清楚。在本项目中，我们拟采用综合研究手段，明确RBM25参与pri-miRNA加工的方式，阐明它与pri-miRNA加工复合体的关系和作用机制，并通过寻找其互作蛋白，深入探索剪切体在pri-miRNA加工中的机制。研究结果不仅能揭示RBM25在pri-miRNA加工中的新功能，还将明确剪切机制和pri-miRNA加工间的关系，具有重要理论意义。

MicroRNAs (miRNAs) are short noncoding RNAs (20-24 nt) that regulate plant growth and adaptation through silencing of their target genes that are associated with various biological processes. Despite the great progress, there are still many key scientific questions regarding the regulation of miRNA biogenesis needed to be addressed. Recently, pri-miRNA splicing during pri-miRNA has drawn great attention, however, the molecular mechanism by which pri-miRNA processing is regulated remains largely unknown. Most recently, we have identified a new splicing factor RBM25 that regulates alternative splicing of HAB1 pre-miRNA and switch on/off of the ABA signaling. Interestingly, RBM25 mutation also affects miRNA biogenesis. Furthermore, we found that RBM25 affects pri-miRNA processing but not transcription; and intriguingly, RBM25 physically interacts with HYL1, a key component of the pri-miRNA processing complex. Together, these results point to a critical role of RBM25 in pri-miRNA processing. In this study, we will adopt a combinatorial research approach to decipher the molecular mechanism underlying the RBM25-mediated pri-miRNA processing. The objectives include: to determine whether RBM25 directly binds to the double strand/single strand pri-miRNAs and its action mode; to search for the splicing enhancers (the recognition and binding site) for RBM25; to elucidate the functional relationship between RBM25 and the pri-miRNA processing complex; to explore the potential regulatory network of RBM25-mediated splicing/processing of pri-miRNAs through screening and functional analysis of the RBM25 interacting proteins. The ultimate goal is to uncover the molecular mechanism through which the splicing machinery and pri-miRNA processing is integrated during miRNA biogenesis. The study will not only reveal a novel role of RBM25 in miRNA biogenesis, but also provide direct evidence that the splicing machinery is involved in pri-miRNA processing. The results obtained will provide novel insights into the mechanism of pri-miRNA splicing/processing and further our understanding of miRNA biogenesis, in particular pri-miRNA splicing.