Investigating the role of MicroRNAs in the zygomorphic expression of flowers in the family Commelinaceae.

The genetic mechanisms underlying the evolution of floral symmetry is an emergent area of research and discovery. While the ABC model of flower development explains organ identity, post-transcriptional regulation, particularly by microRNAs (miRNAs), is a relatively new subject of study. In the monocot family Commelinaceae, closely related species display both radial symmetry (more than one plane of symmetry), and bilateral symmetry (one plane of symmetry). Commelina communis exhibits bilateral symmetry, and Tradescantia subaspera exhibits radial symmetry. Prior studies suggest that repression of a class B MADS-box gene DEFICENS influences this morphology. Direct evidence linking specific miRNAs to symmetry shifts within this family is lacking.

This project aims to bridge that gap by testing the hypothesis that post-transcriptional regulation of the class B MADS-box DEFICENS-like gene by a specific miRNA (miRNA5197) drives floral morphology in C. communis. During Phase one of this project, a miRNA biotin pulldown assay will be conducted to confirm physical binding between miRNA5197 and the DEF-like mRNA target. Upon successful completion of phase one the project will move to phase two where a target mimic transformation using Agrobacterium mediated gene transfer will be employed to inhibit miRNA silencing and restore expression of the suppressed gene. If miRNA regulation is responsible for the bilateral floral morphology of C. communis, disruption of silencing should result in a shift toward radial symmetry. By experimentally validating this interaction, this project would deepen our understanding of floral symmetry evolutionary development, as well as our understanding of miRNA regulation in plants.