Title: Cloning and Identification of MicroRNAs in Wild Soybean (Glycine soja) Running title: MicroRNAs in Wild Soybean Authors:

MicroRNAs (miRNAs) play important roles in post-transcriptional gene silence by directing target mRNA cleavage or translational inhibition. Currently, hundreds of miRNAs have been identified in plants, but no report has been published in wild soybean (Glycine soja). We constructed a small-RNA library consisting of 2880 sequences with high quality, in which 1347 were 19-24 nt in length. By utilizing the miRNA, Rfam and domesticated soybean EST database, we have analyzed and predicted the secondary structure of these small RNAs. As a result, 15 conserved miRNA candidates belonging to 8 different families and 9 novel miRNA candidates comprising 8 families were identified in wild soybean seedlings. All these miRNA candidates were validated by Northern blot and the novel candidates expressed in a tissue specific manner. Furthermore, putative target genes were predicted for novel miRNA candidates and two of them were verified by 5’-RACE experiments. These results provided useful information for miRNA research in wild soybean and plants.