Loss of LOFSEP Transcription Factor Function Converts Spikelet to Leaf-Like Structures in Rice.

()-like genes, which encode a subfamily of MADS-box transcription factors, are essential for specifying floral organ and meristem identity in angiosperms. Rice () has five -like genes with partial redundancy and overlapping expression domains, yet their functions and evolutionary conservation are only partially known. Here, we describe the biological role of one of the genes of rice, , in redundantly controlling spikelet morphogenesis. belongs to the conserved subgroup along with and was expressed strongly across a broad range of reproductive stages and tissues. No obvious phenotype was observed in the single mutants when compared with the wild type, which was largely due to the functional redundancy among the three genes. Genetic and molecular analyses demonstrated that , , and together regulate floral meristem determinacy and specify the identities of spikelet organs by positively regulating the other MADS-box floral homeotic genes. Experiments conducted in yeast also suggested that OsMADS1, OsMADS5, and OsMADS34 form protein-protein interactions with other MADS-box floral homeotic members, which seems to be a typical, conserved feature of plant SEP proteins.