A synthetic model positioning SlARF2 in the regulatory network controlling fruit ripening.

SlARF2 mediates tomato fruit ripening by positively regulating key ethylene biosynthesis genes (ACO1, ACS2/4) and through modulating key regulators of fruit ripening such as RIN, NOR, and CNR transcription factors known to affect ripening by positively regulating ACO1 and ACS2/4. SlARF2A is up-regulated by ethylene while SlARF2B is up-regulated by auxin. SlARF2A negatively regulates the expression of SlARF2B, thus down-regulation of SlARF2A is compensated by an up-regulation of SlARF2B. SlARF2 also modulates the expression of FUL1/2 and TAGL1. It is postulated that SlARF2 negatively regulates at the transcription or at the protein level an unknown factor that acts as a ripening repressor.