Progress on gibberellin-mediated regulatory networks in apple anthocyanin biosynthesis.
Anthocyanins are crucial secondary metabolites in apple, which determine the commercial value of the fruit and confer essential protection against environmental stresses. Their biosynthesis is governed by a complex network of structural and regulatory genes, modulated by developmental cues, environmental factors, and phytohormone signaling. Emerging evidence highlights gibberellins (GAs) as pivotal regulators of anthocyanin accumulation in apple. Here, we review the current understanding of the molecular mechanisms underlying gibberellin (GA)-mediated anthocyanin biosynthesis. We specifically highlight the role of DELLA proteins in orchestrating this GA-mediated regulatory network and examine how post‑translational modifications of DELLA proteins, together with their interactions with other signaling components, influence anthocyanin accumulation. Furthermore, we discuss the intricate crosstalk between GA and other hormonal pathways, particularly jasmonic acid and Strigolactone, revealing how these interactions fine‑tune anthocyanin production. We also explore how GA signaling integrates environmental cues, such as light and temperature, to coordinate anthocyanin levels in apple. Finally, we identify key knowledge gaps in the GA-anthocyanin regulatory network and propose promising directions for future research.