Abstract:

To screen candidate genes involved in flowering regulation in Osmanthus fragrans, this study used the genome of ‘Rixianggui’ as the experimental material and employed bioinformatics methods to identify members of the OfBBX gene family and analyze the physicochemical properties, phylogenetic evolution, synteny relationships both within Osmanthus fragrans and between Osmanthus fragrans and Arabidopsis, and tissue expression patterns of OfBBX genes, combined with cis-acting element prediction. A total of 42 OfBBX genes were identified, encoding proteins with molecular weights ranging from 20.54k to 53.71 kDa, isoelectric points from 4.46 to 8.61, and grand average of hydropathicity (GRAVY) from -0.904 to -0.027. Phylogenetic analysis analysis classified these genes into five groups (I-V) containing 11, 7, 5, 14, and 7 members, respectively, with highly conserved motif structures and B-box/CCT domains across all groups. Tandem duplication and segmental duplication events were detected in OfBBX genes, and 48 BBX syntenic gene pairs were identified between 'Rixianggui' and Arabidopsis. Seven OfBBX genes showed high expression levels in floral tissues, with their promoters containing abundant light-response elements. Notably, OfBBX19 is phylogenetically clustered with, collinear to, and orthologous with AtBBX1 (CONSTANS) and is significantly up-regulated in floral organs. This study identified seven candidate genes including OfBBX18 and OfBBX19, with OfBBX19 potentially acting as a CONSTANS ortholog mediating photoperiod regulation, thereby providing molecular markers for further investigation into the floral organ development mechanism in Osmanthus fragrans.

Key words: Osmanthus fragrans, BBX, gene family, transcription factor, bioinformatics