AGAMOUS Coordinates Flower Development Beyond Organ Identity: AGAMOUS Coordinates Flower Development in Space and Time

Abstract

AGAMOUS (AG) is a C-class Mcm1, Agamous, Deficiens, and Serum response factor (MADS)-box transcription factor classically defined by its roles in specifying stamen and carpel identity and enforcing floral meristem determinacy. Accumulating evidence now indicates that AG also coordinates a series of late developmental programs whose outputs are rewired over time based on tissue context, chromatin state, and phytohormone-mediated inter-organ communication. In the gynoecium, AG promotes regional patterning and tissue differentiation by regulating downstream target genes, thereby supporting ovule- and fruit-related development while safeguarding epidermal fate by repressing ectopic leaf-like traits and inappropriate stomatal differentiation. In stamens, AG integrates epigenetic timing with plant hormonal signaling, where delayed activation of AG targets is associated with the gradual dilution of H3K27me3 marks, and AG-dependent induction of jasmonic acid biosynthesis supports filament elongation and anther progression. Notably, AG activity also extends beyond its expression domain by shaping perianth fate in a non-cell-autonomous manner: jasmonic acid produced in reproductive organs activates transcriptional and autophagy-related programs at the bases of petals, promoting senescence and abscission after anthesis. Together, these findings support a unified view of AG as a regulator of spatiotemporal systems that links the specification of organ identity to late morphogenesis, reproductive maturation, and coordinated organ disposal. This review summarizes recent advances in AG-mediated regulatory networks and highlights how dynamic, multilayered control enables AG to orchestrate late flower development across multiple organs.