Fig. 3

Proteins in endoplasmic reticulum (ER) membrane contribute to ethylene (ET) signaling and fruit development and ripening. Two systems of ET signaling, System-1 and system-2, control different aspects of fruit development and ripening. In system-1 ET signaling, ET controls the expression of SlEIN3/Ethylene Insensitive 3-Like transcription factors (EILs), particularly SlEIL2, by modulating the function of SlEIN2. SlEIL2 mediating cell division and fruit growth. In System-2 ET signaling, ET controls fruit ripening through a regulatory module comprising several key components: ethylene receptors (ETR), Constitutive Triple Responses (CTR), SlEIN2, SlEILs, and developmental transcription factors including Ripening-inhibitor (RIN), Non-Ripening (NOR), Fruitfull1 (FUL1), and EIN3 Binding F-box protein 1 (EBF1). Activated EILs transcriptionally trigger the expression of developmental transcription factor genes, thereby regulating fruit ripening by modulating the function of ripening-related genes