Overexpression of Camellia oleifera ColERF04 accelerates flowering in transgenic Arabidopsis

The asynchronous flowering period of oil-Camellia ( Camellia oleifera ) significantly reduces fruit set and yield, thereby limiting its widespread cultivation. Ethylene Response Factors (ERFs), members of the APETALA2/ERF superfamily, are critical to flower development. Here, we performed a genome-wide survey and identified 181 ERF family members in the C. oleifera genome. Phylogenetic analysis classified these genes into two major subfamilies, DREB and ERF. The expansion of the ERF genes in C. oleifera appears to be largely driven by tandem duplication and large-scale segmental duplication. Expression analyses of duplicated ERF gene pairs across flower developmental stages reveals diverse evolutionary trajectories, encompassing functional redundancy, subfunctionalization, and neofunctionalization among homologous genes. Comprehensive expression profiling across various tissues and flower development stages suggests that ColERF04 is closely associated with flower development, suggesting a role beyond the stress-responsive functions typically reported for A2-group members. Consistent with its putative role as a transcription factor, ColERF04 was experimentally verified to strictly localize to the nucleus. Furthermore, heterologous overexpression of ColERF04 in Arabidopsis significantly accelerated the floral transition providing evidence that ColERF04 has the molecular capacity to promote flowering in a heterologous system. Overall, our study elucidates the evolution and expression patterns of ERFs in C. oleifera and identifies ColERF04 as a promising candidate gene for molecular-assisted breeding, providing a foundational genetic framework for precisely modulating flower development to significantly enhance fruit-setting rates and overall crop yields.