Figure 5.

Model of miRNA triggers and target sites of plant phasiRNA biogenesis. (A) Definition of phased small RNA classes in plants. PhasiRNA-generating loci are called PHAS genes, as tasiRNA-generating loci are TAS genes. (B) Rules and observations of phasiRNAs in plants. The two top cells correspond to PHAS genes with 21-nt miRNA triggers, and the two bottom cells have 22-nt triggers; the left cells have one miRNA-binding site, and the right cells have two binding sites. In each of the four cells, black text in boxes is observations of tasiRNAs previously described in Arabidopsis and in this study; blue text indicates which portion of the cleaved TAS transcript is converted to tasiRNAs. In the top left corner of each cell is indicated the name we ascribed to each class; there is no evidence of 1₂₁ phasiRNAs. (C) Examples of phasiRNAs matching the observations described in B.