Abstract
In eukaryotes, small RNAs play important roles in RNA silencing which are involved in many biological processes. The best studied endogenous small RNAs are microRNAs (miRNAs). In Arabidopsis thaliana, miRNAs are excised from primary miRNA transcripts forming stem-loop structures by the RNase III enzyme DICER-LIKE 1 (DCL1). This enzyme works coordinately with HYL1 and SERRATE. miRNAs are loaded into the RNA-induced silencing complex (RISC) where the complementary mRNAs are cleaved by ARGONAUTE 1, which has the slicer activity. The basic roles of these factors in the biogenesis of miRNA or the regulation of mRNA have been elucidated so far, but it remains incompletely understood how miRNAs regulate the development and physiological condition of plants. Here we studied the phenotype of hyl1 mutant plants which accumulate less miRNAs than wild type plants. Furthermore, we would like to report the possibility of the existence of another factor related to miRNA pathway.
