Flower opening in barley (Hordeum vulgare) is induced by the swelling of the lodicule, a trait under the suppressor protein CLY1 encoded by the cleistogamy1 (cly1). Anwar et al. show a small RNA miR172a was the most abundant among three miR172 isomers, and sequence polymorphism at the miR172a target site within cly1 was relevant to the abundance of the CLY1 protein, but not that of its transcript.
In a Ds-induced Hv-miR172a null mutant, abundance of the CLY1 protein increased, but not that of its transcript, and the lodicules failed to grow, resulting in a non-opening flower. The implication is that miR172a acts to reduce the translation of cly1, which develops lodicules and enables open-flowering.