摘要The plant hormone ethylene is essential for climac-teric fruit ripening,although it is unclear how other phytohormones and their interactions with ethylene might affect fruit ripening.Here,we explored how brassinosteroids(BRs)regulate fruit ripening in to-mato(Solanum lycopersicum)and how they interact with ethylene.Exogenous BR treatment and in-creased endogenous BR contents in tomato plants overexpressing the BR biosynthetic gene SICYP90B3 promoted ethylene production and fruit ripening.Genetic analysis indicated that the BR signaling regulators Brassinazole-resistant1(SIBZR1)and BRI1-EMS-suppressor1(SIBES1)act redundantly in fruit softening.Knocking out SIBZR1 inhibited ripening through transcriptome reprogramming at the onset of ripening.Combined transcriptome deep sequencing and chromatin immunoprecipitation fol-lowed by sequencing identified 73 SIBZR1-repressed targets and 203 SIBZR1-induced targets involving major ripening-related genes,suggesting that SIBZR1 positively regulates tomato fruit ripening.SIBZR1 directly targeted several ethylene and car-otenoid biosynthetic genes to contribute to the eth-ylene burst and carotenoid accumulation to ensure normal ripening and quality formation.Furthermore,knock-out of Brassinosteroid-insensitive2(SIBIN2),a negative regulator of BR signaling upstream of SIBZR1,promoted fruit ripening and carotenoid accumulation.Taken together,our results highlight the role of SIBZR1 as a master regulator of tomato fruit ripening with potential for tomato quality im-provement and carotenoid biofortification.