Representative RNA secondary structure of putative polycistronic clustered miRNAs. Representative examples of (a) a homologous miRNA cluster, Osa-MIR395m-s, x, and (b) a non-homologous cluster, Ath-MIR859-774. Mfold software [66, 67] was used to generate the most probable RNA secondary structures. Mature miRNA sequences are indicated with a line. In the case of the rice cluster, a new miR395 locus (Osa-MIR395x) not yet present in miRBase (version 13.0) was annotated. Ath, Arabidopsis thaliana; Osa, Oryza sativa. Black bar = 10 nucleotides (nt).