Regulation of Flowering Time and Floral Organ Identity by a MicroRNA and Its APETALA2-Like Target Genes

• Published in: The Plant cell Vol. 15; no. 11; pp. 2730 - 2741
• Main Authors: Aukerman, Milo J., Sakai, Hajime
• Format: Journal Article
• Language: English
• Published: United States American Society of Plant Biologists 01.11.2003
• Subjects: APETALA2 gene; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Base Sequence; Developmental biology; Flowering; Flowers - genetics; Flowers - growth & development; Gels; Gene expression regulation; Gene Expression Regulation, Developmental; Gene Expression Regulation, Plant; Genes; Homeodomain Proteins - genetics; Homeodomain Proteins - metabolism; MicroRNA; MicroRNAs - genetics; MicroRNAs - physiology; miRNA; Molecular Sequence Data; Nuclear Proteins - genetics; Nuclear Proteins - metabolism; Nucleotides; Phenotypes; Plant Proteins; Plants; Plants, Genetically Modified; Protein Biosynthesis - genetics; Repressor Proteins - genetics; Repressor Proteins - metabolism; RNA; Sequence Homology, Nucleic Acid; Time Factors
• ISSN: 1040-4651; 1532-298X
• DOI: 10.1105/tpc.016238

MicroRNAs (miRNAs) are ∼21-nucleotide noncoding RNAs that have been identified in both animals and plants. Although in animals there is direct evidence implicating particular miRNAs in the control of developmental timing, to date it is not known whether plant miRNAs also play a role in regulating temporal transitions. Through an activation-tagging approach, we demonstrate that miRNA 172 (miR172) causes early flowering and disrupts the specification of floral organ identity when overexpressed in Arabidopsis. miR172 normally is expressed in a temporal manner, consistent with its proposed role in flowering time control. The regulatory target of miR172 is a subfamily of APETALA2 (AP2) transcription factor genes. We present evidence that miR172 downregulates these target genes by a translational mechanism rather than by RNA cleavage. Gain-of-function and loss-of-function analyses indicate that two of the AP2-like target genes normally act as floral repressors, supporting the notion that miR172 regulates flowering time by downregulating AP2-like target genes.