Fig. 1

Evolutionary rate in the conserved and non-conserved miRNA genes of Oryza. Average substitution rates of different regions of miRNA genes and all the protein-coding genes of Oryza. All the regions of miRNA genes have much less substitution rates compared to protein-coding genes. The secondary axis depicts the substitution rate for protein-coding genes (a). Percentage of different nucleotide substitutions in the miRNA genes. T↔C transitions are more frequent in conserved miRNA precursors, whereas A↔G transitions occur more recurrently in non-conserved miRNAs (b). Schematic representation of three portions of an average sized 21 nt miRNA and miRNA* (c). Proportion of conserved sites in the different portions (left, middle and right portions) of mature and star regions of the miRNAs. Left portion (having the seed sequence) of miRNA and right portion (pairing with the left portion of miRNA) of miRNA* show higher conservation in both conserved as well as non-conserved miRNAs (d)