SlFERL Interacts with S-Adenosylmethionine Synthetase to Regulate Fruit Ripening.

Fruit ripening is a complex and genetically programmed process modulated by transcription factors, hormones, and other regulators. However, the mechanism underlying the regulatory loop involving the membrane-protein targets of RIPENING-INHIBITOR (RIN) remains poorly understood. To unravel the function of tomato ( ) (), a putative MADS-box transcription factor target gene, we investigated and addressed the significance of in fruit ripening by combining reverse genetics, biochemical, and cytological analyses. Here, we report that RIN and Tomato AGAMOUS-LIKE1 (TAGL1) directly bind to the promoter region of and further activate its expression transcriptionally, suggesting a potential role of in fruit ripening. Overexpression of significantly accelerated the ripening process of tomato fruit, whereas RNA interference knockdown of resulted in delayed fruit ripening. Moreover, a surface plasmon resonance assay coupled with tandem mass spectrometry and a protein interaction assay revealed that SlFERL interacts with the key enzyme -adenosyl-Met synthetase 1 (SlSAMS1) in the ethylene biosynthesis pathway, leading to increased -adenosyl-Met accumulation and elevated ethylene production. Thus, SlFERL serves as a positive regulator of ethylene production and fruit ripening. This study provides clues to the molecular regulatory networks underlying fruit ripening.