套索RNA是RNA拼接过程中被剪切的内含子形成的，传统上认为它被去分支酶DBR1线性化后降解。但近年来发现动植物中很多套索RNA逃逸线性化并参与基因表达调控。然而，DBR1如何识别并线性化套索RNA以及套索RNA选择性逃逸线性化的机制和生物学意义尚不清楚。本项目在申请人近期发现植物套索RNA被miRNA加工复合物识别的基础上，围绕"套索RNA如何被识别或者选择性逃逸、套索RNA是否被加工成小RNA及其生物学意义是什么“等科学问题，开展如下研究：1）鉴定DBR1互作蛋白及下游因子，阐明套索RNA被线性化的机制；2）分离生理条件下套索RNA的结合蛋白，解析套索RNA选择性逃逸线性化的调控机制；3）从外源转基因、病毒侵染和转座子入侵三方面研究套索RNA衍生的小RNA在基因组受到攻击时的功能。上述研究将全面揭示套索RNA的代谢调控机制，阐明套索RNA作为植物的免疫分子在基因组稳定性维持中的作用。

Lariat RNA is a by-product of RNA splicing, which is linearized by DBR1 followed by degradation. However, several studies showed that hundreds of lariat RNAs exist in physiological condition, and these lariat RNAs act as regulatory molecues to control gene expression. Currently, how DBR1 recognizes and linearizes lariat RNA, how a subset of lariat RNAs escape debranching, whether lariat RNAs bound by the Dicer complex can be further processed into small RNA, and what the biological consequences of these lariat-derived small RNA remain unexplored. In this study, we will focus on three aspects: 1) identify DBR1-interacting proteins and isolate dbr1-2 suppressor, aiming to elucidate the mechanism of DBR1 linearizing lariat RNAs; 2) Isolate factors involved in lariat RNA production and degradation, and uncovers the mechanism of lariat RNAs escaping debranching; 3)Investigate the role of lariat-derived small RNA in the control of genome stability from transgene silencing, virus infection, and transposon invasion. Through these investigations, we hopefully understand the mechanism of lariat RNA metabolism, and uncover a previously unknown role of lariat RNA in the maintenance of genome stability during evolution in plants.