Dicer or Dicer-like (DCL) proteins in gen silencing process has function and involved in the digestion of long double stranded RNAs with argonaute protein. Dicer-like (DCL) proteins one of the members of RNaseIII family and has key rolls in creation of small RNA. This protein cut the double RNA strand and convert that two RNA strand. The purpose of this research, study of Dicer-like (DCL) proteins in poplar (Populus trichocarpa L.) by using bioinformatic tools. Amino acid sequences of Dicer-like of the poplar and arabidopsis was received from the target databases by using BLAST tools. Then sequences were aligned by using the CLC Sequence Viewer 6 software. Continue domains, the phylogenetic tree and Three-dimensional structure of these sequences was plotted and finaly more features of these proteins determined. This study showed poplar has 7 Dicer-like protein Generally poplar Dicer-like proteins had PAZ, DEXDc, RIBOc and HELICc domains and according to the phylogenetic trees of Populus trichocarpa Dicer-like proteins are divided in four class. Weight and lengths of this protoeins respectively are 152 – 221 kDa and 1351-1967 amino acid. The results of the study could be a prelude for a more comprehensive study of these proteins in poplar.
