Genetic coupling of floral rewards and signals underlies pollinator attraction

Animal pollinators underpin biodiversity and global agriculture, yet the molecular mechanisms that coordinate floral rewards and signals to attract pollinators remain poorly understood. Through phenotyping melon genetic diversity, we identified nectarless1 (nls1), encoding the YABBY-family transcription factor YABBY5 (YAB5), as a central integrator of pollinator-attracting traits. YAB5 interacts with CRABS CLAW (CRC) during nectary initiation to specify nectary identity by repressing alternative floral organ fates. As flowers mature, YAB5 directly activates 4-α-glucanotransferase 2 (DPE2) to promote starch remobilization required for nectar secretion and promotes petal growth and flower opening. In petals, YAB5 directly engages an MYB111-dependent flavonoid pathway that generates UV nectar guides, while indirectly influencing floral volatile emission. Disrupting YAB5, DPE2, or MYB111 reduces pollinator visitation. Together, these findings reveal how a developmental regulator couples organ specification with organ-specific metabolic programs to synchronize floral rewards and signals at anthesis.