Figure 1. The gain and loss of 21 conserved miRNA families across date palm and seven other plant species.

The taxonomic tree was constructed in the Interactive Tree Of Life (http://itol.embl.de/) from taxonomy numbers in NCBI (http://www.ncbi.nlm.nih.gov/Taxonomy/). The history of miRNA genes was reconstructed using the maximum likelihood procedure implanted in COUNT software. The dates of genomic duplication events are from references. The black bars represent the conserved segment, and the triangles indicate the presence of an miR167 locus in the extant plant genomes. Total refers to the total number of miRNA genes in a specific plant, and the number in brackets is the number of miRNA families.