position-of-origin analysis of Chinese cabbage csRNA. To normalize the varying rRNAs or tRNAs length, RNA sequences were divided into 5% blocks from the 5' to the 3' ends. The flanking sequence outer of each ends were calculated proportionally. The positions of csRNA 3' ends and 5' ends were plotted into rRNA (A) and tRNA (B) blocks, respectively. (C) The peak of 3' ends of rRNA-derived csRNAs at the 3' termini of rRNA. (D) The peak of 5' ends of tRNA-derived csRNAs at the 5' termini of tRNA.