A cis-NAT candidate locus yields 21-nt enriched siRNAs. (A) cis-NAT pair of no apical meristem gene (NAM, 013132 m) and unannotated gene (020539 m) in Cassava. The EST track displays the EST sequences from the Phytozome database . (B) Small RNAs from the positive and negative strands are displayed above and below the NAT pairs, respectively. The red and blue regions on the gene model represent exons and introns, respectively.