Discovering numerical laws of plant microRNA by evolution

MicroRNAs (miRNAs) are small non-coding RNA molecules with important post-transcriptional regulatory roles. They are found in most eukaryotic cell types, including a diverse range of plant species. Previous research has demonstrated that numerical features of miRNA genes, based on sequence and structure, can be indicative of a particular miRNA's specialty. We carried out a large-scale analysis to discover the laws of the relationship between numerical features and evolution. Basic statistical methods were applied to 132 numerical features of 3343 miRNA genes from phylum levels to family levels. Results demonstrated that there were three significant classes among candidate numerical features, the conserved, the increased and the decreased with evolutionary time based on phylum levels. Furthermore, the conserved numerical features among families are usually also conserved among phyla and the features increasing with evolutionary time tended to be related to A or U nucleotides, while the features decreasing with evolutionary time tended to be related to G or C nucleotides. Our results confirm the strong relationship between numerical features of miRNA and species evolution. This research will greatly assist in elucidating the numerical laws of plant miRNA based on evolution.