真核生物中，mRNA降解和基因沉默是调控RNA稳态的重要途径，在植物的生长发育中发挥重要作用。本课题组前期研究发现，细胞质双向mRNA降解途径通过及时清除缺陷形式的RNA底物，防止其进入RDR6和SGS3介导的转录后水平基因沉默（PTGS），保证内源基因正常表达。然而，当mRNA降解途径发生异常后，缺陷形式的mRNA选择性进入PTGS途径的机制尚不清楚。申请人前期通过酵母双杂交筛选和蛋白互作验证发现，参与细胞质mRNA降解的因子LSM1和PAT1与PTGS途径核心组分RDR6/SGS3在体内外均相互作用。通过小RNA测序等手段初步发现，LSM1和PAT1可能影响RDR6/SGS3的活性。此外，本项目还发现LSM1与细胞质双向mRNA降解途径在生化和遗传上也相互作用。因此，本项目拟进一步探究LSM1和PAT1在介导mRNA降解与基因沉默途径底物识别中的具体作用及其作用机理。

In eukaryotes, mRNA degradation and gene silencing are important ways to regulate RNA homeostasis and play an essential role in plant growth and development. Our previous study found that cytoplasmic bidirectional mRNA degradation could prevent the defective form of RNA substrates from entering the post-transcriptional level gene silencing (PTGS) mediated by RDR6 and SGS3 and ensure the normal expression of endogenous genes by timely removing the aberrant RNA substrates. However, when mRNA degradation is abnormal, the mechanism of the defective form of mRNA selectively entering the PTGS pathway is still unclear. Previously, we found that the factors involved in cytoplasmic mRNA degradation, LSM1 and PAT1, interact with the core component, RDR6/SGS3, in the PTGS pathway in vivo and in vitro through yeast two-hybrid screening and protein-protein interaction experiment. Through small RNA sequencing and other assays, it was preliminarily found that LSM1 and PAT1 may affect the activity of RDR6/SGS3. In addition, we also identified biochemical and genetic interactions between LSM1 and the cytoplasmic bidirectional mRNA degradation. Therefore, this project intends to further explore the specific role and mechanism of LSM1 and PAT1 in mediating substrate recognition in mRNA degradation and gene silencing pathway