Figure 12.

A general regulatory model depicting the role of SlERF.D7 in controlling tomato fruit ripening. SlERF.D7 functions in ethylene and auxin-dependent manner and directly activates the transcription of SlARF2A and SlARF2B. Thus, down-regulation of SlERF.D7 leads to severe impairment of ARF2 orthologs and causes a delayed fruit ripening phenotype. On the contrary, OE of SlERF.D7 promotes ripening traits by directly activating ARF2 orthologs. Further functional and physiological dissection reveals a positive connection between the mode of action of ARF2 orthologs and fruit ripening process. Taken together, SlERF.D7 emerges as an integrator of ethylene and auxin biosynthesis and signaling pathways, which work synergistically with SlARF2A or with both SlARF2A and SlARF2B to achieve the competency of the fruits to ripen. SAM, S-adenosyl methionine; NR, never-ripe; ETR4, ethylene receptor4; and AUX/IAA, auxin/indole-3-acetic acid.