Protein phosphatase PP2C2 dephosphorylates transcription factor ZAT5 and modulates tomato fruit ripening.

Although C2H2 zinc finger transcription factors are important in plant growth, development, and stress resistance, their specific roles in fruit ripening have been less explored. Here, we demonstrate that the C2H2 zinc finger transcription factor 5 (SlZAT5) regulates fruit ripening in tomato (Solanum lycopersicum L.). Overexpression of SlZAT5 delayed ripening, while its knockout accelerated it, confirming its role as a negative regulator. SlZAT5 functions as a transcriptional repressor by directly inhibiting ripening-related genes, including SlACS4, SlPL8, and SlGRAS38, thereby delaying ripening. Furthermore, SlZAT5 interacts with the type 2C protein phosphatase SlPP2C2, which regulates the repressor activity of SlZAT5 by dephosphorylating SlZAT5 at Ser-65. This interaction is crucial in modulating ethylene production, thereby influencing the ripening process. These findings reveal a regulatory function of SlZAT5 in tomato fruit development, offering insights into the SlZAT5-SlPP2C2 module and potential targets for genetic modification to improve fruit quality and extend fruit shelf life.