Production of transgenic rice plants showing reduced heading date and plant height by ectopic expression of rice MADS-box genes

Plant architecture is an important factor that controls several characteristics, such as light interception, harvest index, and lodging. Plant architecture is controlled by a group of regulatory genes. It was previously found that ectopic expression of some MADS-box genes resulted in early flowering and a dwarf habit in Arabidopsis and tobacco (Nicotiana tabacum) plants. To explore ways to alter heading time and heading height, we expressed ectopically several OsMADS (Oryza sativa MADS-box) genes in rice plants. The OsMADS cDNA clones were connected to the maize ubiquitin promoter in the sense orientation, and the constructs were introduced into rice plants by the Agrobacterium-mediated transformation. Ectopic expression of the rice MADS-box genes hastened flowering to varying extents. RNA-blot analyses revealed that the phenotypes of early flowering and dwarfism were correlated with the transcript level of the transgene. In addition, weak expression of OsMADS1 using the nopaline synthase (nos) promoter, shortened the heading time by a few days and resulted in a mild reduction of heading height without any pleiotropic effects. The present study suggests that the rice MADS box genes could be used as sources of early-flowering and dwarfing traits in monocot species.