Rice Papers

鍘诲勾鐨勪竴绡嘝lant Cell瑙�杩欏効锛屼粖骞村湪Molecular Cell鍙堝彂涓�绡囷紝甯堝厔浣犳槸鎴戜滑鐨勫伓鍍忋��

DNA Methylation Mediated by a MicroRNA Pathway [鍏ㄦ枃] [鎰熻阿绾㈠啗闀垮緛璁哄潧鐨刴hl]

In plants, the known microRNAs (miRNAs) are produced as 锝�21 nucleotide (nt) duplexes from their precursors by Dicer-like 1 (DCL1). They are incorporated into Argonaute 1 (AGO1) protein to regulate target gene expression primarily through mRNA cleavage. We report here the discovery of a class of miRNAs in the model monocot rice (Oryza sativa). These are 24 nt in length and require another member of the Dicer family, DCL3, for their biogenesis. The 24 nt long miRNAs (lmiRNAs) are loaded into AGO4 clade proteins according to hierarchical rules, depending on the upstream biogenesis machinery and the 5鈥�-terminal nucleotide. We demonstrated that lmiRNAs direct DNA methylation at loci from which they are produced as well as in trans at their target genes and play roles in gene regulation. Considered together, our findings define a miRNA pathway that mediates DNA methylation.