Key transcription regulators in the formation of yellow traits in rose petals.

Rose is a famous ornamental flower worldwide, and its flower color is an important ornamental trait. The formation of yellow petals is primarily determined by carotenoids, yet its regulatory mechanism is largely unknown. Here, the main carotenoid components in yellow petals were β-carotene and violaxanthin. The enzyme-encoding genes playing a crucial role in the carotenoid biosynthesis pathway were RhLYCB, RhZEP, and RhVDE. Transcription factors RhMYB3, RhMYB305, RhMYB30, and RhERF23 were identified as key regulatory genes based on transcriptomics and metabolomics. Transcript levels of these genes were closely associated with petal coloration during flower development and in an F1 population. Overexpression of RhMYB3, RhMYB305, RhMYB30, and RhERF23 significantly promoted carotenoid accumulation, as well as the expression of structural genes, in both rose petals and tobacco leaves. Further validation through molecular interaction (Yeast single hybrid and EMSA) confirmed that these genes bound to the promoter of RhLCYB and RhCRTISO, thereby activating their expressions and contributing to the enhanced carotenoid content. Moreover, RhMYB305 interacting with RhMYB3, RhMYB30, and RhERF23 promotes carotenoid accumulation in tobacco leaves and rose petals. Collectively, we propose that RhMYB3, RhMYB305, RhMYB30, and RhERF23 play a pivotal role in enhancing carotenoid biosynthesis, which will facilitate the modulation of carotenoid accumulation in rose and quality breeding through molecular design.