Genome-Wide Identification of the Auxin Response Factor (ARF) Gene Family and Their Expression Analysis during Flower Development of Osmanthus fragrans

Auxins have long been implicated in many aspects of plant growth and development. Auxin response factors (ARFs) are important proteins in auxin-mediated pathways and they play key roles in plant physiological and biochemical processes, including flower development. Endogenous indoleacetic acid (IAA) levels were measured and ARFs were studied in the flowers during the developmental stages in order to further elucidate the role of auxin in flower development of Osmanthus fragrans. A systematic analysis of OfARFs was conducted by carrying out a genome-wide search of ARFs. A total of 50 ARF genes (OfARFs) were detected and validated from the Osmanthus fragrans genome. Furthermore, a comprehensive overview of the OfARFs was undertaken, including phylogenetic relationship, gene structures, conserved domains, motifs, promoters, chromosome locations, gene duplications, and subcellular locations of the gene product. Finally, expression profiling, while using transcriptome sequencing from a previous study and quantitative real-time PCR (qRT-PCR), revealed that many OfARF genes have different expression levels in various tissues and flower developmental stages. By comparing the expression profiles among the flower developmental stages, and the relationship between ARFs and endogenous IAA levels, it can be supposed that OfARFs function in flower development of O. fragrans in an auxin-mediated pathway.