A Conserved Genetic Pathway Determines Inflorescence Architecture in Arabidopsis and Rice

The spatiotemporal architecture of inflorescences that bear flowers determines plant reproductive success by affecting fruit set and plant interaction with pollinators. The inflorescence architecture that displays great diversity across flowering plants depends on developmental decisions at inflorescence meristems. Here we report a key conserved genetic pathway determining inflorescence architecture in Arabidopsis thaliana and Oryza sativa (rice). In Arabidopsis, four MADS-box genes, SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1, SHORT VEGETATIVE PHASE, AGAMOUS-LIKE 24, and SEPALLATA 4 act redundantly and directly to suppress TERMINAL FLOWER1 (TFL1) in emerging floral meristems. This is indispensable for the well-known function of APETALA1 in specifying floral meristems and is coupled with a conformational change in chromosome looping at the TFL1 locus. Similarly, we demonstrate that the orthologs of these MADS-box genes in rice determine panicle branching by regulating TFL1-like genes. Our findings reveal a conserved regulatory pathway that determines inflorescence architecture in flowering plants. [Display omitted] ► SOC1, SVP, AGL24, and SEP4 directly repress TFL1 in emerging floral meristems ► SOC1, SVP, AGL24, and SEP4 interact with AP1 to repress TFL1 ► Repression of TFL1 is associated with a conformational change in gene looping ► Function of SOC1, SVP, AGL24, and SEP4 is conserved in Arabidopsis and rice TFL1 homologs commonly regulate the developmental transitions that allow plant meristems to produce flowers. Liu et al. show that four MADS-box transcription factors collectively influence chromosomal conformation at the Arabidopsis TFL1 locus, repressingTFL1 in floral meristems. Similar requirements in rice imply a conserved transcriptional strategy to control inflorescence architecture.