Identification and characterization of the gene OvANS associated with purple flower in Orychophragmus violaceus

The color of flowers plays a crucial role in ornamental plant breeding, impacting its market value significantly. Orychophragmus violaceus, a traditional ornamental flower cultivated for its early blooming in spring, often exhibits white flower variations during the breeding process, enhancing its ornamental appeal. This study systematically identified 98 genes associated with anthocyanin biosynthesis in O. violaceus, distributed across 12 chromosomes. Secondly, we conducted an analysis of expression patterns and differentially expressed genes (DEGs) of anthocyanin biosynthetic pathway-related genes in O. violaceus by utilizing comparative transcriptome data from white (OvW-1) and purple (OvP-37) flower petals. Our findings revealed significant differential expression of genes ANS, GST, TCP3 and AHA10 between the white and purple flower colors. Subsequently, we employed qRT-PCR to validate the differential expression of OvANS and OvTCP3 in OvW-1 and OvP-37 flowers, with OvANS showing significantly higher expression levels in OvP-37 plants. Moreover, we successfully cloned the complete sequence of the OvANS gene from OvW-1 and OvP-37 flowers, revealing the presence of two inserted fragments in the promoter region of the OvANS gene in white flowers, potentially playing a crucial role in gene expression repression. Subsequently, we conducted qRT-PCR analysis to investigate the expression pattern of the OvANS gene in various tissues (leaves, petioles, petals, and young siliques) of OvW-1 and OvP-37 flowers. Our findings demonstrated that OvANS was ubiquitously expressed in all four tissues of OvP-37, with the highest expression level observed in petals, whereas its expression in OvW-1 was negligible. Our results provide new insights into the molecular mechanism of flower color variation in O. violaceus, and provide a reference for enriching the flower color types of O. violaceus.