Florigen in rice: complex gene network for florigen transcription, florigen activation complex, and multiple functions

► Two florigen genes, Hd3a and RFT1 are essential for flowering in rice. ► Regulation of two florigen genes involves a complex genetic network. ► The florigen activation complex (FAC) composed of Hd3a, 14-3-3, and OsFD1 promotes flowering. ► Examples of multiple functions of florigen are emerging. Regulation of flowering time directly influences successful rice grain production; thus, the long history of domestication and breeding has improved the genetic network of flowering. Recent advances using molecular genomic approaches have revealed the targets of these modifications and the underlying molecular mechanism for flowering. These efforts contributed to identifying the molecular nature of the systemic floral signal ‘florigen’ and have shown how florigen functions, how florigen expression is controlled, and how regulatory pathways are diversified. In this review, we summarize the advances in our understanding of the detailed molecular and genetic mechanisms that allow rice plants to produce flowers at the proper time to ensure grain production.