Comparative study on sequence characteristics of mature and precursor miRNAs of monocot and dicot plants.

MicroRNAs (miRNAs) negatively regulate mRNAs at post-transcriptional level and thus can regulate different biological processes. Here we analyze the sequence characteristics and length distribution of miRNA sequences of six monocot and six dicot plants. We observe a species specific nucleotide preference of miRNAs. Although the first position of 5' end of mature miRNAs is U rich, there exists a wide variation. While the GC% of monocot mature miRNAs in general is nearly equal to the AU%, the GC% of stress induced miRNAs is significantly higher than AU%. Thus, higher content of GC% can be used as a signature of stress induced miRNAs in monocot. The length distribution of mature miRNAs shows the highest peak at 21 nucleotides with some other minor peaks at 20, 22 and 24 nucleotides. The synthesis of some miRNAs has positional preference either to 5' or to 3' arm of their precursors, but they are different in monocot and dicot. [ABSTRACT FROM AUTHOR]