AUTHOR=Dai Zhengyan , Wang Jiang , Zhu Mulan , Miao Xuexia , Shi Zhenying 

TITLE=OsMADS1 Represses microRNA172 in Elongation of Palea/Lemma Development in Rice

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.01891

DOI=10.3389/fpls.2016.01891

ISSN=1664-462X

ABSTRACT=<p>Specification of floral organ identity is critical for the establishment of floral morphology and inflorescence architecture. Although multiple genes are involved in the regulation of floral organogenesis, our understanding of the underlying regulating network is still fragmentary. MADs-box genes are principle members in the ABCDE model that characterized floral organs. <italic>OsMADS1</italic> specifies the determinacy of spikelet meristem and lemma/palea identity in rice. However, the pathway through which <italic>OsMADS1</italic> regulates floral organs remains elusive; here, we identified the microRNA172 (miR172) family as possible regulators downstream of <italic>OsMADS1</italic>. Genetic study revealed that overexpression of each miR172 gene resulted in elongated lemma/palea and indeterminacy of the floret, which resemble the phenotype of <italic>osmads1</italic> mutant. On the contrary, overexpression of each target <italic>APETALA2</italic> (<italic>AP2</italic>) genes resulted in shortened palea/lemma. Expression level and specificity of miR172 was greatly influenced by <italic>OsMADS1</italic>, as revealed by Northern blot analysis and <italic>In situ</italic> hybridization. Genetically, <italic>AP2-3</italic> and <italic>AP2-2</italic> over expression rescued the elongation and inconsistent development of the lemma/palea in OsMADS1RNAi transgenic plants. Our results suggested that in rice, <italic>OsMADS1</italic> and miR172s/<italic>AP2</italic>s formed a regulatory network involved in floral organ development, particularly the elongation of the lemma and the palea.</p>