Beyond light signaling: the broad regulatory spectrum of AFPs in plant growth and development

AFPs (ABI5-BINDING PROTEINS) are a unique class of small, plant-specific proteins, originally identified through their interaction with ABI5 (ABSCISIC ACID INSENSITIVE 5), a pivotal transcription factor in ABA (ABSCISIC ACID) signaling pathway. Emerging evidence indicates that AFPs act as multifunctional integrators governing not only ABA signaling but also a broad spectrum of plant growth, development, biotic and abiotic stress adaptation. This review systematically summarizes the domain architecture, interactome networks, and evolutionary conservation of AFPs, and further highlights the pleiotropic functions of AFPs in seed dormancy and germination, photoperiodic flowering, plant architecture modulation, abiotic stress tolerance and disease resistance. Through diverse molecular mechanisms, including recruitment of corepressors, control of target protein stability, and modulation of chromatin states, AFPs operate as microprotein modulators at critical nodes of phytohormone networks, offering novel insights into the regulatory principles balancing plant growth and stress resilience.