Fruit firmness is a key quality trait affecting marketability, yet the regulatory mechanisms underlying softening remain poorly understood. In fig (Ficus carica L.), we identified an AP2/ERF transcription factor, FcDREB1, as a repressor of fruit softening. FcDREB1 binds directly to the promoters of the key softening-related genes pectate lyase 7 (FcPL7) and polygalacturonase 12 (FcPG12) to suppress their expression and reduce PL and PG activity. Furthermore, we discovered FcERF71, an ethylene-induced AP2/ERF protein, which interacts physically with FcDREB1 and weakens the latter's trans-repression effect on FcPL7 and FcPG12. Notably, FcERF71 also directly inhibits FcDREB1 transcription. This intricate interplay between FcERF71 and FcDREB1 reveals a dynamic regulatory module for balancing key cell-wall-modifying enzymes during fig fruit ripening. Our findings elucidate the complex regulatory network governing fig fruit softening, paving the way for targeted genetic strategies to improve the storability.
Fan et al. (Fri,) studied this question.