Abstract: MiRNA is a kind of endogenous small RNA about 21-25 nuleotides in length that plays important roles in plant morphology and development. The present study was performed to establish a novel system for plant miRNA knockdown in vivo, supply a enegetic tool for miRNA function analysis. Unlike the original target mimicry vector method, we obtained multi-copyed target mimicry sequences using self-ligation method with designed specific DNA fragment based on miRNA motif, construct expression vector and transform to Arabidopsis thaliana. Starting with the conserved miRNA in Arabidopsis, we obtained six transgene lines of miRNA knockdown. We detected the relative expression of related miRNA targets in transgene plants, resulting obviously up-regulated compared with the relative expression in wild type. Based on target mimicry vector construction, we obtained MIM stable lines in Arabidopsis, successfully established a general and high effective miRNA knockdown system in plant species.

Key words: miRNA , Knockdown, Plant , Novel method