A microRNA as a translational repressor of APETALA2 in Arabidopsis flower development

Plant microRNAs ( miRNAs) show a high degree of sequence complementarity to, and are believed to guide the cleavage of, their target messenger RNAs. Here, I show that miRNA172, which can base-pair with the messenger RNA of a. oral homeotic gene, APETALA2, regulates APETALA2 expression primarily through translational inhibition. Elevated miRNA172 accumulation results in. oral organ identity defects similar to those in loss-of-function apetala2 mutants. Elevated levels of mutant APETALA2 RNA with disrupted miRNA172 base pairing, but not wild-type APETALA2 RNA, result in elevated levels of APETALA2 protein and severe. oral patterningdefects. Therefore, miRNA172 likely acts in cell-fate specification as a translational repressor of APETALA2 in Arabidopsis flower development.