The RhEIN3–RhARGOS–RhHYD1 module connects ethylene and sterol signaling to regulate flower opening in rose

For rose (Rosa hybrida) plants, flowering is not only a reproductive and survival strategy but also a determinant of their ornamental value. Ethylene is a critical plant hormone that accelerates flower opening, and sterols are important regulatory factors in the ethylene signaling pathway; however, the molecular regulatory mechanisms through which sterols influence that pathway are not fully understood. Here, we demonstrate that the sterol isomerase HYDRA1 (RhHYD1) participates in ethylene-induced flower opening in rose, and that AUXIN-REGULATED GENE IN ORGAN SIZE (RhARGOS) interacts with RhHYD1 and promotes its degradation. Knocking down RhHYD1 transcript levels resulted in delayed flower opening and reduced ethylene sensitivity. Conversely, knocking down RhARGOS accelerated flower opening and increased ethylene sensitivity. Additionally, we determined that ETHYLENE INSENSITIVE3 (RhEIN3), a pivotal transcription factor within the ethylene signaling pathway, binds to the RhARGOS promoter via TCTTCA motifs to promote RhARGOS transcription. In summary, our findings reveal that a RhEIN3-RhARGOS-RhHYD1 module regulates rose flower opening by connecting ethylene and sterol signaling, providing valuable insight into the mechanism underlying ethylene-promoted flower opening.